Clear Print
An evidence-based review of the research on typeface legibility for
readers with low vision.
April 2006
Lead author: Elizabeth Russell-Minda, M.A., VREBR Project Coordinator
Co-authors: Jeffrey Jutai. Ph.D., C.Psych., VREBR Project Director
Graham Strong, O.D., M.Sc., VREBR Investigator
Collaborators: Kent Campbell, Ph.D., Bloorview KidsRehab
Deborah Gold, Ph.D., CNIB Research
Lisa Pretty, CNIB Communications
Lesley Wilmot, CNIB Communications
This report is a collaborative effort of the VREBR Project Team and CNIB Research.
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April 2006
Copyright Statement
This document is considered the property of the VREBR Project Team and CNIB Research. No part
of this document shall be copied, quoted, or distributed without permission from the authors.
Electronic distribution or saving to another file type (such as .rtf or .html, for example) is also
prohibited.
Contact Information
Please address correspondence about this document to:
Dr. Jeff Jutai, National Director of Research, CNIB
University of Western Ontario,
Dept. of Physical Medicine & Rehabilitation
Parkwood Hospital Site
Hobbins Building, Suite H-403
801 Commissioners Rd. East
London, ON N6C 5J1
(519) 685-4292 x42626
E-mail: jjutai@uwo.ca
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Contents
Executive Summary
4
Key Points Summary
5
Objective of this Review
6
Key Areas of Focus
6
Inclusion and Exclusion Criteria
6
Reading and Low Vision
7
Eye Conditions that Affect Reading Ability
7
Variables that Affect Text Legibility and Readability
8
Overview of Font Characteristics
11
Research and Performance Measures
13
Research Organizations
14
Guidelines and Standards
15
International Guidelines and Standards
15
Search Process and Methodology
17
Overview
17
Evaluating and Selecting the Evidence
17
Table of Individual Studies Selected for Review
19
Conclusions
22
Choice of Typeface and Size
22
Serifs or Sans Serifs
23
Letter Spacing or Crowding
23
Letter Confusion
24
Psychophysics of Reading Experiments
24
References
25
Appendix I—Studies and Publications Selected for Review
30
Appendix II—Study Attributes Table
32
Appendix III—Search Strategies
48
Appendix IV—Guidelines and Standards
49
Ranges of Reading Ability
49
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Executive Summary
The objectives outlined in this report were to review the existing research literature related to the
legibility and readability of typefaces, to locate any standards or guidelines related to typeface design
and legibility (international or national), and to address any French language typeface characteristics
(accent marks, for example) for low vision readers of print copy. Although it was not the primary goal
of this review, any literature related to the legibility of medication labelling was also considered. By
using evidence-based models and methods, the literature was synthesized and assessed in order to
formulate conclusions and make recommendations based on these analyses. A comprehensive
literature search was conducted on multiple online databases, grey literature sources, and general
Web searches. After a careful analysis of search results, abstracts were read and full-text articles
were retrieved for further dissemination and assessment. The studies selected for review were
grouped by their evidence level, based on a model developed by Sackett, et al † and other well-known
centres for evidence-based practice. Since the studies selected for this review were primarily case
series designs, we did not perform further rating with an instrument for assessing study quality‡, as
had been done for the previous chapters of the Vision Rehabilitation Evidence-Based Review. This
assessment tool is valid for randomized controlled trials and non-randomized controlled trials such as
cohort and case control study designs.
This review highlights the fact that multiple variables can affect the reading performance of individuals
with low vision. Certainly, the size and type of fonts used in large print materials are some of the most
important considerations, however, after assessing the research included in this review, it is clear that
other factors can play a role in determining the best conditions for legibility. The presence or absence
of serifs, contrast of text to page, thickness of letters, interletter spacing, leading, and the medium on
which text is printed (medication labels for example), can all affect the legibility of type. In addition,
the role of typeface legibility plays an important part with respect to specific eye conditions.
Individuals with age-related eye diseases were the most common type of participants within the
research studies assessed in this review, and there were many studies conducted on the specific
issues associated with reading and age-related macular degeneration.
Based on the evidence presented in this review, typeface legibility for readers with low vision is a
verifiable and important consideration when developing printed materials. However, we also found
several studies where the ultimate outcome for subjects regarding choice of font (both style and size)
was based primarily on personal preference. Interestingly, custom designed fonts for large print
materials and blindness or low vision conditions, such as Tiresias, were preferred by individuals with
low vision over standard fonts such as Times Roman or Arial. With respect to international standards
and guidelines on typeface legibility and design, the best evidence was to be found with individual low
vision and blindness organizations, national library services’ recommendations, and other “grey”
sources, such as documents published on the various Web sites. Our search for French language
considerations, such as accent marks and low vision reading, produced nothing of significance.
In summary, we found that the overall body of research on low vision reading and typeface legibility
characteristics is somewhat inconsistent, with an absence of controlled trials. Most of the literature
included in this review consists of case series designs with small sample sizes. As with “typical”
evidence-based reviews, it was difficult to assess the literature in this regard as there were no
randomized controlled trials, and thus systematic analyses could not be made. Alternatively, this
review may serve as a “revelation,” highlighting the need for further research on typeface legibility
and its associated characteristics for individuals who hope to retain their ability to read printed
materials.
†
Canadian Task Force on the Periodic Health Examination: The periodic health examination. CMAJ. 1979;121:1193-1254.
‡
Downs S and Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of
randomised and non-randomised studies of health care interventions. J Epidemiol Comm H. 1998;52:377-384
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Key Points Summary
Evidence base for typeface legibility and low vision:
Although it is well-accepted and researched that typeface affects legibility, there is
minimal evidence addressing how specific font characteristics contribute to legibility for
readers with visual impairment.
There is a larger body of research evidence on reading and low vision, in general (not
with typefaces specifically), using experimental, quantitative, and psychophysical
methods of measuring reading performance.
Evidence-based conclusions for typeface legibility and low vision:
Large print reading materials can be helpful for low vision conditions such as age-related
macular degeneration, cataract, glaucoma, diabetic retinopathy, and any other condition
where reading print is difficult, especially when central vision is affected.
Based on several studies, there is some indication that at very small character sizes,
sans serif font types (e.g., Arial) can increase reading speed.
There is very little evidence that seriffed fonts (such as Times Roman) actually reduce
legibility and hence, reading performance.
Font style or typeface family can affect reading speed, but this may also depend on
individual preferences.
According to one study, they did not find increased legibility over and above standard
fonts such as Times Roman, when compared with prototype software for adjustable
fonts. All participants reading acuities improved with the adjustable font (total legibility
gain 75%).
The results of one, unpublished scientific report, showed that low vision subjects found a
customized sans serif large print font (Tiresias) more legible than the other standard
typefaces (Arial and Times Roman).
Two studies (one published and one unpublished) on the legibility and preference of
typeface style and size for medication labelling, found that subjects preferred sans serif
fonts such as Arial (16-22-point depending on VA) and Adsans (16-point).
One study on patient literature for potential cataract patients, found that 65% of subjects
found the Universe 14-pt. typeface to be the most legible, compared to Century
Schoolbook, a seriffed font.
High contrast typeface improves reading performance and is generally preferred by most
observers (black text on white background, or white text on a black background, for
example).
Interletter spacing (“crowding”) is shown to impact reading speed. The more crowded the
letter are, the slower the reading speed.
Reading with peripheral vision, rather than central vision, is slower. This may be
attributed to “crowding” of letters in the visual field.
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Objective of this Review
Key Areas of Focus
This review includes a comprehensive search of the literature on typeface (font) legibility and
characteristics for any form of vision loss that affects reading performance with printed copy. This
review also includes a search of any international standards for font size, type, and characteristics for
readers with low vision, when reading printed materials.
Inclusion and Exclusion Criteria
The search and inclusion criteria for this review includes the following: controlled or uncontrolled;
experimental or non-experimental; randomized or non-randomized; and published or unpublished
research related to typeface legibility for readers with low vision, specifically when reading printed
copy. The inclusion criteria for “low vision condition” includes any eye condition where reading printed
copy causes some amount of difficulty. In addition, any literature related to the French language and
typeface legibility research was considered. Since French is one of the official languages in Canada,
it seemed particularly important to attempt to locate any low vision research related specifically to
French language typeface legibility and specifically, the impact of diacritical marks (accents) on
reading with low vision. The secondary inclusion criteria for this review include any international
guidelines or standards that have been established for typeface legibility for the print disabled.
Although extremely important to low vision users, any literature devoted to factors associated with
online (the Web) font characteristics (accessible CSS styles, for example), computer interface
characteristics, or accessibility issues, is excluded from this review.
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Reading and Low Vision
Reading is critical to full participation in modern society. For the many individuals with impaired vision,
reading presents a major challenge for many activities of daily living. Low vision can be functionally
defined as the inability to read the newspaper or recognize faces, with the best refractive correction,
at a normal reading distance of 40 cm.1 Many older people have difficulty reading standard text,
including medical information, hospital forms, and medication labels, even with appropriate
magnification and illumination. Successful rehabilitation primarily involves enhancement of whatever
usable vision remains.2 The most direct method for enhancing vision is magnification, usually
consisting of relatively portable and inexpensive hand-held or stand magnifiers, or electronic devices
such as CCTVs and other electronic vision enhancement systems. Environmental modifications such
as proper illumination and viewing distance are also important variables to consider when reading.
Due to problems associated with high levels of magnification, such as reduction in the size of the
usable field, enhancing legibility by manipulating the typographic presentation can reduce or eliminate
magnification requirements.2 Some people who can read standard print may find it tiring and prefer to
read large print whenever they can. Small characters printed with fine strokes, on patterned
backgrounds are especially problematic and difficult to read. The majority of readers who use large
print appear to be over retirement age,3 and age-related macular degeneration (AMD) is the leading
cause of low vision in most developed countries. Non-electronic, large print reading materials typically
consist of books, newspapers, and magazines.
Eye Conditions that Affect Reading Ability
In terms of causing difficulties when reading print, the following low vision conditions are among the
most prevalent. This should therefore be considered a selective listing, not representative of every
possible low vision condition.
Age-Related Macular Degeneration
Internationally, AMD is one of the leading causes of visual impairment. It is also the most common
cause of losing the ability to read print, since it affects central or foveal vision, which is used for
seeing detail. Magnifiers can be helpful in the early stages of AMD, and large print materials help
prolong the ability to read. Since AMD is a degenerative disorder, it progressively affects the macular
region of the retina, often resulting in an irreversible central scotoma. People with central scotoma
must use peripheral vision to read, which has been shown to be a slow and inefficient process
according to research in this area.1-7
Cataract
Cataract is another common age-related eye condition where the lens of the eye becomes cloudy or
opaque. If vision is blurred by cataracts, which can affect word recognition, reading performance will
be degraded by reduced speed and fluency. 8 With severe cataract, people can see light and detect
colour contrast, but usually cannot read print. When cataracts reach an advanced stage and receive
laser treatment, patients can usually begin to read large print. Reading materials with good contrast
can help people with cataracts.
Glaucoma
Since glaucoma is considered a “tunnel vision” condition, central vision is usually unaffected, allowing
the person to continue to read print. However, peripheral vision is usually affected. As people with
glaucoma age, they will usually require progressively larger print materials.
Diabetic Retinopathy
Diabetic retinopathy (DR) is another major cause of vision loss for working-age adults. DR can often
lead to patchy vision resulting in orientation difficulties. Some people with patchy vision have a fairly
even sight loss across the visual field and may require print materials with good contrast and large
print. Some individuals may lose peripheral sight first, and can continue to read standard sized text
for longer periods.
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Variables that Affect Text Legibility and Readability
There are many factors that can add or detract to the legibility and readability of typefaces. The
following variables can affect readers with low vision (explained in more detail below): contrast,
colour, heaviness, point size, leading, letter spacing, and font family or style. The design of a typeface
can significantly affect legibility and readability. For many applications the aesthetic appearance of
the text is the basis on which a font is selected. However, there are occasions when legibility is the
paramount consideration (for example, warning or danger notices). 9
There are subtle differences in definitions of “legibility” and “readability.” “Legibility” is generally
considered as a measure of the recognizability of the characters and how easily they can be read,
based on the visual appearance in a given environment. Vernon (1931) 10 found the following letters
confusing: f & t, l & t, c & e, n & a, i & j, l & J. Burt (1974)11 found it necessary to distinguish between
l 1 ! i and h & b, C & G, Q & O, J & F, R & Q. For numerals, Tinker (1928)12 found 3 5 8 2 to have low
legibility. “Readability” as defined by McNally (1913) 13 is the extent to which a given type size or form
lends itself to being read with the absence of visual effort. It can also be thought of as subjective ease
and comfort to read.9 The following categories are the most common variables that affect both
legibility and readability for individuals with varying forms of visual impairment.
Contrast
Many individuals with low vision have contrast sensitivity deficits, and have difficulty visually with
objects that are poorly contrasted with their surroundings.14 People with central vision loss, who use
parafoveal vision for reading, are especially affected by issues related to contrast. General guidelines
recommend that text should be printed with the highest possible amount of contrast. There is also
good evidence that for many low vision readers (older or partially-sighted) that light (white or yellow)
letters on a dark (black) background are more readable than dark letters on a light background. There
is little difference in reading speed for white-on-black presented text versus black-on-white, for
character sizes ranging from 0.006 to 12 degrees.5
Type Colour
The choice of text colour can affect low vision readers. Partial sight, aging and congenital colour
deficits all produce changes in perception that reduce the visual effectiveness of certain colour
combinations. Two colours that contrast sharply to someone with normal vision may be far less
distinguishable to someone with a visual disorder.15 It is difficult to achieve very high contrasts with
colour combinations other than black and white. Colour combinations that provide the maximum
brightness contrast, such as black on white, and black on yellow give the best legibility results.16 It is
generally recommended that coloured text be used for larger or highlighted text, such as headlines
and titles.17
Heaviness
The heaviness of a font can have an effect on legibility since it distorts the space within the letters
and makes them less legible.18 It is generally recommended that medium heaviness be used and light
type should generally be avoided. For emphasis, bold fonts may be used, rather than italics or allcapitals. 19 Some studies have shown relationships between font heaviness and other characteristics
and specific low vision conditions. Shaw noted that readers with cataract were aided by the increase
in the weight of the print.20 Bold type has been shown to be beneficial for individuals with glaucoma. 21
Shaw added that once point size is increased above threshold size, weight becomes a more
important factor than point size. Another important factor to consider is the stroke width of text. Stroke
thickness is especially important for low vision readers because thinly stroked letters result in poor
contrast.
Point Size
Point terminology for specifying print size is the method used by printers to specify the size of metal
block on which raised print was embossed. Each “point” unit is 1/72 inch or approximately 0.353 mm.
A major problem with point terminology is that different font styles with the same point size will have
different letter heights and dimensions.22, 23 Perhaps the most accepted guideline for low vision
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reading materials is that type should be large, preferable at least 16 to 18 points. The relationship
between readability and point size differs somewhat among typefaces and this should be taken into
consideration when developing print materials. Research evidence has shown that low vision readers
require larger print, although there is no consensus for optimum character size for large print
publications. For normally sighted readers, characters subtending 0.3 degree (or 18 minutes) to 2
degrees are best.24 This corresponds to a type point size range of 9 to 14. The range of visual ability
is highly variable from one individual to the next. Low vision and reading ability can range from nearnormal to functional blindness. Each individual will have his or her own reading threshold. Since it
would be impractical to create publications with varying point sizes, the use of low vision aids
(magnification devices in particular) should be suggested for low vision readers.
Leading (Spacing between lines of text)
Leading, or spacing between lines of text, should be at least 25 to 30 percent of the point size. This is
because many people with partial sight have difficulty finding the beginning of the next line while
reading.17 Some research points to optimal leading ranges of 1 to 4 points with heavier typefaces
requiring more leading.19 Others have suggested that four point leading should be used when
preparing materials for low vision readers. This corresponds to 5 to 8 minutes between the tops of an
upper case letter and the bottom of the letters on the line above. 25
Figure 1 Examples of leading§
Letter Spacing
Closely packed small letters are much harder to read compared to the same letters presented in
isolation.26 Reduced letter legibility in the presence of other letters or features has been termed the
“crowding effect.”27 Research in this area has examined the effects of legibility on interletter spacing,
letter size, letter contrast, stroke width, letter aspect ratio, presentation duration and retinal location.
Individuals with compromised macular functions often use eccentric viewing and preferred retinal loci
for reading, and close letter spacing, or letter “crowding” reduces their reading performance. 28 Arditi
suggests that where possible, spacing should be wide, and monospaced fonts, rather than
proportionally spaced fonts appear to be more legible for those individuals with low vision. 17
Font Family and Style
While there is little reliable information on the comparative legibility of typefaces, there is some
evidence that a Roman typeface, using upper and lower cases, is more readable than italics, oblique,
or condensed text. Mansfield, et al (1996) found Courier to be slightly more legible than Times
Roman30, and others have argued the opposite.29 In general, there is disagreement in the research as
§
Arditi A. Making Text Legible: Designing for People with Partial Sight. Lighthouse International 2000. See:
http://www.lighthouse.org/print_leg.htm
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to which type of font is the most legible for low vision readers. Standard serif and sans serif fonts
(such as Arial or Times Roman) are generally considered to be the best fonts for legibility. There is
some evidence that sans serif fonts are more legible when character size is small relative to the
reader’s visual acuity.17
Other text and print publication considerations include margin space, paper finish, and
distinctiveness. Extra-wide binding margins are helpful in bound material because it makes it easier to
hold the volume flat. Spiral binding can be helpful as well. Many low vision aids, such as stand and
video magnifiers, are easiest to use on a flat surface. Paper finish or texture can have an impact on
low vision reading. Glossy surfaces can produce additional glare. Opaque or matte finish paper is
recommended.25 In addition, publications that look similar in design and layout can cause confusion
regarding the ability to distinguish one publication from another. The use of distinctive colours, sizes
and formats on the covers can be especially helpful to older individuals and those who are visually
impaired.17
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Overview of Font Characteristics
Spacing
The two main types of font pitch are fixed-width and proportionally-spaced. In fixed-width fonts (such
as Courier New), each character takes up the same amount of horizontal space, whereas in a
proportionally-spaced font (such as Times or Arial), different letters take up different amounts of
horizontal space.30
Fixed-width font (Courier New)
Proportionally-spaced font (Times New Roman)
Proportionally-spaced fonts can pack in more characters into a line of text than fixed width fonts, and
are thus preferred by typographers. However, there is little research on how these spacings affect
reading and low vision. Arditi, et al 199031 and Beldie32 have investigated this issue. Beldie found
variable pitch characters provide significantly better performance in reading speed and proofreading,
but did not specify the type of character used in the experiment. Arditi, et al found that for small
characters, the fixed-width pitch produced the fastest reading, with a modified variable width yielding
better performance than variable width spacing, indicating crowding effects.
Letter Height (x-height and t-height)
In addition to point size, the x-height and the t-height can be adjusted for large print materials and
research has shown that letter height and point size influence legibility. The x-height is defined as the
height of the letter “x” in any given font, and is the specific height of the lower case letters. The “theight” is defined as the height to the bottom of the crossbar of the letter “t” in any given font (lower
case). Refer to Figure 2 below. Depending on the font, t- and x-height may be different heights or the
same.
Figure 2 Example of t-height and x-height (100 pt. APHont not shown to scale)**
Serifs
Serifs are the fine lines that extend horizontally from the main strokes of a letter.33 According to the
definition put forth by Merriam-Webster, serifs are "any of the short lines stemming from and at an
angle to the upper and lower ends of the strokes of a letter." It has been a common conception that
the purpose of serifs is to guide the reader’s eye horizontally while reading. However, the
effectiveness of serifs in this regard remains somewhat controversial. Examples of serif fonts include:
Times, Palatino, Garamond, Century Schoolbook, and Book Antiqua. Serif fonts are frequently used
in newspapers and books where the space for print is tight.
**
Kitchel EJ. Large Print: Guidelines for Optimal Readability and APHont a font for low vision. Retrieved March 27,
2006 from http://www.aph.org/edresearch/lpguide.htm.
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The quick brown fox (Times)
The quick brown fox (Palatino)
The quick brown fox (Book Antiqua)
Sans-Serifs
Sans-serif fonts (from the French word sans, or “without”) are those fonts which have letters with
straight lines and no curls or appendixes. Sans-serif fonts have been determined to be more readable
than serif fonts, but again, these results are disputable. In these studies, researchers did not hold
other font characteristics constant, such as stroke width, size, or ornamentation. 34 Examples of sansserif fonts include: Arial, Helvetica, Tahoma, Avant-Garde, Univers, Century Gothic, Verdana, and all
other fonts characterized by clean letterforms.
The quick brown fox (Arial)
The quick brown fox (Tahoma)
The quick brown fox (Century Gothic)
Figure 3 Examples of serifs and sans serifs.††
Stroke Width
Stroke width refers to the width of each component or stroke of a letter. A font may have a uniform
stroke width in which all of each stroke is the same width, for example the font Arial. Or, a font may
have a varying stroke width in which some portions of the stroke are thinner than others, as seen in
the font Times New Roman.34 Fonts may also have a generally wide stroke width, referred to as
“bold,” or a thin stroke width, referred to as “light.” It has been shown (Yager, et al 1998) 35 that letters
with uniform stroke width appear to be more legible, as do letters that are bold (Krulee and Novy
1986).36
††
See: http://www.symplebyte.com/general_usage/fonts/serif_or_sans-serif.html
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Research and Performance Measures
Legibility and Readability of Fonts
The legibility and readability of fonts has been studied by examining the individual characteristics of a
font, or by studying differences among whole fonts. There are limitations to both approaches, in that
they may lead to different conclusions. Research on specific font characteristics, such as stroke width
or the use of serifs, requires manipulation of individual parameters while keeping others constant.
While this approach allows direct assessment of the influences of specific font characteristics have on
legibility, it often becomes impractical due to the requirement of constructing artificially created fonts.
Alternatively, researching whole fonts, such as Times or Helvetica, which may be easily used in
practical application, limits the generalizability with respect to specific characteristics. One can
generalize results only to fonts closely resembling the chosen font. 34
Reading Acuity
Optotype-based acuity tests such as Jaeger and N-notation are discouraged because they are often
flawed and poorly standardized.37 There is a good deal of evidence from psychophysical experiments
that typography can significantly impact what is known as reading acuity—the minimum size of print
that can be read both in normal and low vision (Tinker 196338 and Arditi 199639). Reading acuity and
maximum reading distance are other commonly used measures of legibility. Results from some
studies have shown that certain font characteristics such as stroke width (Arditi, et al 199540; Berger
194441, 42), aspect ratio (Arditi, et al 199543; Berger 194844; Soar 195545), inter-letter spacing (Arditi, et
al 199540; Arditi, et al 199746; Moriarty and Scheiner 198447; Whittaker, et al 198948), and the
presence or absence of serifs (Arditi and Cho 200549), have some impact on text legibility.2
Reading Speed and Critical Print Size
A frequently used criterion for determining legibility is reading speed. The only published quantitative
data comparing low vision reading speeds for different fonts seem to be those of Mansfield, et al
(1996)30, who found reading speeds for different fonts to be 10% slower with Times New Roman than
with Courier (for normal subjects, Times Roman had a speed advantage by 5%). Although the
manipulation of font parameters may significantly affect reading acuity, the gains in reading speed for
low vision are modest, at best.2 Another common performance metric used in text legibility and
reading research is “critical print size.” The critical print size is the smallest print size at which
individuals can read with their maximum reading speed. This is an important measure as it indicates
the minimum magnification required for effortless reading. The critical print size is most easily
identified from a plot of the patient's reading speed at each print size.
Crowding and Peripheral Vision
For many people with low vision where the central retina is damaged, reading can be difficult. People
with retinal disorders such as AMD, tend to read with their peripheral vision. However, studies have
shown that reading in the peripheral visual field is slower than reading with central vision. One
hypothesis for the slow reading speed is enhanced crowding in peripheral vision. Crowding refers to
the decreased visibility of a visual target in the presence of nearby objects. 50 Some studies have
suggested that increased letter spacing and other controls of letter characteristics may reduce this
“crowding effect.” On the basis of previous research, there is enough evidence to suggest that
reading speed may benefit from increased letter spacing, and more so in peripheral than central
vision.51
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Rapid Serial Visual Presentation (RSVP)
With Rapid Serial Visual Presentation (RSVP) reading, words are presented rapidly at a fixed location
on a video display (not unlike cell phone text messaging). This type of reading reduces the amount of
eye movement required and reading speed typically increases, up to 3-4 times faster than normal.52
In addition, RSVP facilitates reading on limited screen sizes such as displays used by low vision
users who require large type. The RSVP reading technique is frequently implemented as an
assessment method for studies on reading performance and the effects of typographical features on
visually impaired observers. During RSVP, readers can read sans serif typefaces about 20% faster at
very small sizes, but this advantage disappears at larger sizes. 53
Research Organizations
Arlene R. Gordon Research Institute—Lighthouse International
The Arlene R. Gordon Research Institute within Lighthouse International has produced experimental
research, guidelines, and reports on text legibility and font characteristics. Dr. Aries Arditi, a senior
fellow in vision science at the Institute, and colleagues, have produced some of the few, published
studies on font characteristics and legibility for individuals with visual impairment.
American Printing House for the Blind
The American Printing House for the Blind promotes independence of blind and visually impaired
persons by providing specialized materials, products, and services needed for education and life. The
APH Research Department conducts ongoing product development activities in such areas as tactile
graphics, Braille reading readiness, and low vision. Their in-house developed font, APHont was
developed by a fontographer to the specifications of APH and contains characteristics that have been
shown to enhance reading speed, literacy, comprehension, and usability for large print users.
Royal National Institute for the Blind (RNIB) and Tiresias
RNIB manages research projects, works with external research partners and contributes to relevant
research and evidence studies. The RNIB also offers guidelines for making text more legible and
accessible for low vision users (see RNIB Web site). Through affiliations with RNIB, Dr. John Gill and
colleagues have published scientific research on text legibility and have developed a customized font
family called Tiresias. The Tiresias family of fonts has a number of applications and has been
customized for large print, electronic displays (such as ATMs), television screens, and signs. It has
been specifically designed for individuals with low vision.
University of Minnesota Low Vision Research Lab
A series of research studies on the psychophysics of reading54 were conducted at the Minnesota
Laboratory for Low-Vision Research by Gordon E. Legge and colleagues. The Psychophysics of
Reading series consists of nineteen published studies, and one unpublished study, related to
psychophysical methods of measuring reading performance. Observers are required to read aloud
individual lines of text that are scanned across a television monitor. The scanning rate is increased
until the observer begins to make mistakes. Reading rate, in words per minute, is computed after
correction for errors. At some scanning rates, the reading rate is maximal; the maximal reading rate
can be measured as a function of any stimulus or observer variable.5 Other studies in this series on
low vision reading report on the effects of character size, character spacing and number of characters
simultaneously present in the field, sample density, and contrast polarity. 24 This research lab is also
responsible for the development of the MNREAD Acuity charts, which are continuous text reading
acuity charts for normal and low vision. The charts are used to assess how reading performance
depends on print size. Three measures of reading performance are easily obtained: Reading acuity
the smallest print that can just be read, maximum reading speed the reading speed when
performance is not limited by print size, and critical print size the smallest print that supports the
maximum reading speed. The MNREAD Acuity Charts have a wide range of applications in testing
normal and low vision: prescribing optical corrections for reading, or other near tasks in the eye clinic,
in low vision assessment, prescribing magnifiers or other reading aids, applications in paediatrics and
special education, and research.55 Charts are currently being developed in Japanese, Italian, French,
Spanish, Norwegian, Danish, Swedish and Portuguese.
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Guidelines and Standards
International Guidelines and Standards
During our search for international font legibility standards or guidelines for low vision readers, we
located primarily online documents and grey literature (unpublished by journal standards, but
published online). We could not locate any definitive international standards or guidelines on font size
and type for reading with low vision. Perhaps the closest example of a “standard” in this regard, is a
document published by the International Council of Ophthalmology, entitled Visual Standards:
Aspects and Ranges of Vision Loss,56 which contains information and a chart on the ranges of visual
acuity and reading ability. This chart outlines estimated ranges of reading ability and which types of
low vision aids would benefit each range of vision loss. The ranges of reading ability closely match
the visual acuity ranges, in general (Appendix IV—Guidelines and Standards).
We did find that most international library councils, printing houses and foundations for the blind and
visually impaired (Canada, US, UK, and Australia), have guidelines and standards for large print
materials. (See Appendix IV for a detailed listing of these organizations). In general, there was
agreement between these organizations on standards for printed material in terms of acceptable font
size and other text characteristics that increase legibility and accessibility. The International
Federation of Library Associations and Institutions 57 has published a report on guidelines for
development for libraries for the blind.58 This purpose of the report is to provide guidelines, on an
international level, to libraries and governments for developing library services for the print disabled.
The report outlines suggestions for font size, type, and other considerations for large print materials.
Although we found no national standards or guidelines for text legibility in Canada, the Canadian
Library Association has produced a report on their strategy for a national network for equitable library
services for Canadians with print disabilities. 59 The goal of this project is to ensure that more
materials in alternative formats will be produced in a coordinated, efficient and cost effective manner.
In addition, this project hopes to ensure that these materials are made available in the most
accessible way possible. The report also calls for standards and guidelines to be established
regarding a number of issues related to accessible library materials for low vision and blind readers.
Canada’s largest bilingual library service for the blind and visually impaired is the Canadian National
Institute for the Blind (CNIB). The CNIB produces accessible reading formats for this population, and
typically produces between 2,000 and 2,500 audio and Braille titles a year. Other agencies in
Canada, such as the Institut Nazareth et Louis Braille (INLB) in Quebec and the Montreal Association
for the Blind also provide these types of materials. In addition, many provinces including British
Columbia, Ontario, and Manitoba provide alternative format material through their post-secondary
institutions.
In the United States, the Arlene R. Gordon Research Institute within Lighthouse International,60 has
produced a significant body of vision, psychosocial, and evaluation research, and is composed of a
multidisciplinary team of psychologists, sociologists, computer scientists, and social welfare
researchers. The institute has published guidelines on effective contrast, text legibility, and effective
design of print publications for the partially sighted. 15, 17 The American Printing House for the Blind’s
(APH) research and development group, has also published guidelines on the optimal readability of
large print.61
In the UK, Tiresias.org,62 a research unit of the Royal National Institute for the Blind (RNIB), devotes
itself to aspects surrounding vision loss and text legibility. Their scientific research unit has produced
a number of reports and guidelines on fonts and text legibility.63 Through the work of Dr. John Gill and
associates, this organization is responsible for the development of fonts such as the Tiresias font
family. These fonts were specifically researched and created for members of the low vision
community, and are used for various applications such as large print reading materials (LPfont),
information labels (Infofont), control labels (ATMs, calculators, and telephones for example) (Keyfont),
screen systems (PCfont), television titling (Screenfont), and sign systems (Signfont)
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Guidelines and Standards for Medication Labelling
The legibility of medication labels for visually impaired populations is an important concern. In our
search for medication labelling and typeface legibility standards in Canada and the United States, we
located several sources outlining rules and regulations concerning standardized formats for healthrelated information and medication (non-prescription or over-the-counter—OTC) labelling. The U.S.
Department of Health and Human Services, Food and Drug Administration report on OTC labelling
requirements64 contains recommendations for medication labelling, and although these are guidelines
for the general population, they could certainly be extrapolated to individuals with low vision. Based
on consumer feedback, the report suggests using at least a 6-point type size for all OTC labelling and
recommends the font style be “any clear, easy-to-read type style,” suggesting the use of Helvetica or
Univers (sans serif fonts). With respect to the contrast of the labels and drug fact sheets, the agency
recommends that type be “all black or one dark color, printed on a white or other light, neutral color,
contrasting background.”
A Canadian Public Health Association publication entitled, “Good Medicine for Seniors: Guidelines for
Plain Language and Good Design in Prescription Medication” 65 outlines suggestions for legible and
clear design for medication labelling. These guidelines are based in part, on a technical report
published by the Nonprescription Drug Manufacturers Association of Canada.66 Both recommend the
use of sans serif fonts for packaging (Helvetica, Arial, and Univers, for example) if the type size is
smaller than 10 points. Other suggestions include the appropriate use of white space, leading, type
alignment, line length, contrast, and emphasis. Their recommendation regarding contrast is in line
with almost all other guidelines on contrast: dark lettering on a light surface; brightness and high
contrast help readability and glossy or reflecting surfaces do not. When the type is small, leading
should be adjusted so that the space between lines increases by about two points.
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Search Process and Methodology
Overview
In our search for the literature on font legibility for readers with low vision, all types of study designs
were considered: prospective and retrospective; qualitative and quantitative; experimental and nonexperimental; published and unpublished; and systematic or standard literature reviews. See also
“Secondary Sources: Grey Literature” below. The search parameters were limited to the following
criteria: English language, with no specific limits on subject age or year of publication. Although the
focus of the search was limited to literature in English, we also considered studies related to French
language type characteristics (diacritical marks—or “accents”), as this was applicable to specific
populations with low vision in Canada. The search concluded in March 2006.
Keyword Selection
The types of keywords used included MeSH, non-MeSH, and OVID database-specific headings,
combined with single or multiple keywords, when searching the major online databases. When
searching secondary or Web-based sources, specific keywords and standard search operators were
used. For the standards and guidelines search, keywords included: guidelines for text legibility,
readability, and/or font size, standards for text legibility and font size, large print, type or letter
spacing, and high contrast text. Refer to Appendix III—Search Strategies, for additional keywords
used in the search.
Primary Sources: Online Databases
The following major, online databases were searched for research studies: CINAHL, EBM Reviews
(includes CDSR, ACP Journal Club, DARE, and CCTR‡‡), EMBASE, MEDLINE-OVID, and PubMed.
A search for research studies as well as grey literature was conducted via the following secondary
database sources: AgeLine, Arts and Humanities Index, Canadian Business and Current Affairs
(CBCA) Business, Education, and Reference, Dissertation Abstracts Online, ERIC, IEEE Xplore, MLA
International Bibliography, Public Affairs Information Service (PAIS) International, ProQuest
Education, Psychology, and Research Library, PsychInfo, Sage Full-Text Collections: Communication
Studies, Education, Psychology, Nursing & Health Sciences, SCOPUS, Social Sciences Abstracts,
Web of Science, Web of Knowledge, and WorldCat.
Secondary Sources: “Grey” Literature, Organizations, and Web Searching
In order to locate international or national standards and guidelines on text legibility, all potential
sources of grey literature were searched. Grey literature typically consists of abstracts, unpublished
studies, conference proceedings, graduate theses, books (or specific chapters), reports from
governments, companies, societies or organizations, applications, editorials, and letters. We
performed general keyword searches on the Web (via Google and Ask.com), grey literature
databases, and organizations (primarily via Web sites) related to low vision and blindness, major
optometric and ophthalmologic societies, and any other relevant organization or source. For a
complete list of grey literature databases and sources, see Appendixes III and IV.
Evaluating and Selecting the Evidence
Results
Our primary database literature search resulted in approximately 60 citations. In our secondary,
expanded database search, we located and additional 58 references (including dissertations). In
addition, a hand-search of studies based on references cited in well-known studies on font
characteristics and text legibility experiments produced 65 citations. We therefore located a total of
183 references. We found no randomized controlled trials (RCTs) on font characteristics or text
‡‡
Evidence-Based Medicine (EBM) Reviews include: Cochrane Database of Systematic Reviews (CDSR), ACP Journal
Club, Database of Abstracts of Reviews of Effectiveness (DARE), and Cochrane Controlled Trials Register (CCTR).
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legibility for low vision readers of print copy. One study selected for review, randomly selected
patients from a low vision clinic in Glasgow, in order to determine the best type size for medication
labels.67 However, these subjects were not randomized to intervention groups, and aside from the
random selection, it was essentially a case series design. In addition, we found no evidence
regarding French language typeface characteristics or legibility, or diacritical marks (accents).
However, it seems plausible that the findings on typeface legibility reviewed here can be generalized
to visually impaired readers of French.
Individual Studies Selected for Review: Methodology
From the total number of references, abstracts were reviewed and articles were assessed according
to the inclusion and exclusion criteria listed above. Full-text articles were then obtained and selected
for review based on appropriateness to the inclusion criteria. All studies were then categorized by
design: cohort, case control, case series, and grey literature, based primarily on the organizational
model proposed by Sackett, et al.68 For this review, we added an extra level of evidence to include
grey literature sources (not originally proposed by Sackett). For a list of studies and grey literature
sources selected for this review, see Studies and Publications Selected for Review—Appendix I. All
of the studies selected for review (17 total) contain research on some form of font legibility in relation
to low vision reading. A good majority of the studies included subjects with normal vision and sample
sizes were usually small. Two studies selected for review centered on font legibility issues related to
medication labelling and the development of printed materials for patients with low vision. Since this is
a potential concern for aging and low vision populations, we felt that it was worthy of consideration in
a review on font legibility for the visually impaired.
Levels of Evidence
Level
Description
Total
Reviewed
I
Evidence based on well-designed, randomized, controlled
trials; systematic reviews; or meta-analyses.
0
II
Evidence based on well-designed cohort studies and their
systematic reviews.
2
III
Evidence based on well-designed case control studies
and their systematic reviews.
0
IV
Evidence based on well-designed case series,
nonexperimental, descriptive studies.
13
V
Evidence based on expert opinion without explicit critical
appraisal, or based on physiology, bench research, or
“first principles.”
0
VI
Grey literature (published or unpublished): technical
reports, guidelines, abstracts, dissertations, etc.
2
The 17 individual studies (published and unpublished) selected for this review are summarized on the
following table, which includes the study source information, number of subjects, and results or
findings. Studies are classified in order of their level of evidence. In order to present a more detailed
picture of each study selected for review, a study attributes table was created, through the extraction
of data (Appendix II). The authors of this review have attempted to ensure every possible level of
transparency when formulating conclusions based on the current evidence.
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Table of Individual Studies Selected for Review
Author, Year
Evidence Level
Country
No. of
subjects
Results or Findings
92
There are small, but significant advantages of Courier over Times in
reading acuity, critical print size, and reading speed for subjects with low
vision. For normal subjects, the differences are slighter, with an advantage
in reading speed for Times. For print sizes close to the acuity limit, the
choice of font could make a significant difference in reading performance
(for both normal and low vision).
260
The difference in mean words read between close-set type and mean
words read set in regular type was significant for the close-set type effect.
No difference in reading speed was found between the serif and sans serif
typefaces. There was no significant effect on reading speed as a result of
the interaction of letter spacing and typeface.
4
In general, the presence or absence of serifs made no difference in
reading speed, for all participants, both normally sighted and with low
vision. There was an extremely small observed effect of serif size in
experiment 1, which used an acuity criterion of legibility. However, due to
this extremely small effect size, the authors conclude no difference in
legibility between typefaces that differ only with the presence or absence
of serifs.
40
When using the prototype font adjustment software, visually impaired
users produced a variety of distinct fonts, which resulted in enhanced
legibility (legibility gain averaged 75%). This study did not demonstrate
increases in legibility over and above standard fonts such as Times New
Roman.
Arditi A, et al 1990
Case series
USA
4
For small characters, fixed width (FW) produced the fastest reading, with
modified variable width (MVW) yielding better performance than variable
width (VW) spacing, indicating crowding effects. For medium and large
characters (~0.25 to 6 deg height), performance was best with VW,
slowest with MVW, and intermediate with FW spacing. RSVP of text show
that higher text density and lower eye movement requirements of VW text
is responsible for superiority at medium and large character sizes.
Chung S 2002
Case series
USA
6
Increased letter spacing beyond the standard size, which presumably
decreases the adverse effect of crowding, does not lead to an increase in
reading speed in central or peripheral vision. Subjects had normal vision.
Mansfield JS, et al
1996
Cohort
USA
Moriarty SE and
Scheiner EC 1984
Cohort
USA
Arditi A & Cho J
2005
Case series
USA
Arditi A 2004
Case series
USA
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Author, Year
Evidence Level
Country
No. of
subjects
Results or Findings
Chung S, et al
1998
Case series
USA
6
Print size is not the limiting factor for maximum reading speed in
peripheral vision. Subjects all had normal vision; the authors suggest
extending findings regarding the effects of print size on reading speed to
low vision population.
180
Subjects with best-corrected VA lower or equal to 6/24 showed a
significantly diminished ability to read the instructions on their eye drops
bottles (p<0.001 for each comparison). Subjects preferred Arial font point
sizes of 16 for the 6/24 group, 18 for 6/36, and 22 for 6/60.
52
65% of patients admitted for cataract surgery found the Universe (sans
serif) 14-point typeface the most legible, when reading samples of patient
literature. Black print on a white background was the preferred
colour/contrast choice.
4
Increased random guessing and lateral interactions between features of
neighbouring letters can account for most of the acuity deterioration
observed under narrow-spacing conditions. The font used was
METAFONT, a font design language.
3
When information about the length of letter strings is uncertain, observers
tend to underestimate the lengths of small, closely packed letter strings.
Typically, the observers tend to omit one of the interior letters or combine
two neighbouring letters under such conditions.
6
Six subjects participated in an experimental strategy, using pilot data, to
improve peripheral letter recognition by modifying typographic design
features, based on psychophysical data. Arial Bold was the font used. The
findings show that the most frequently confused letter pairs can vary
between subjects. In addition, if one feature is modified in each of two out
of ten frequently confused letter pairs, the mean recognition performance
can be improved significantly.
Drummond SR, et
al 2004
Case series
Scotland
Estey A, et al 1990
Case series
Canada
Liu L and Arditi A
2001
Case series
USA
Liu L and Arditi A
2000
Case series
USA
MacKeben M. 2000
Case series
USA
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Author, Year
Evidence Level
Country
No. of
subjects
Results or Findings
Morris RA, et al
2002
Case series
USA
27
The authors set out to examine the effects of serifs on RSVP reading
performance. Using a modified Lucida font family in their experiment (both
serif and sans serifs), the results suggest that rendering serifs at small
sizes may be counterproductive.
4
Most typographic variation has little or no effect on reading rates for
characters at normal reading sizes. Fonts corresponding to 6-point and
perhaps smaller type require adequate letter spacing. Crowding effects
due to inadequate spacing are significantly worse for poorly rasterized
fonts, than for well-rasterized ones.
46
Out of 20 subjects with normal vision, 16 read the sans-serif font Swiss
more rapidly than the Dutch (seriffed font). The lower-case x-height of both
fonts was approximately 5.5 times as large as letter acuity, and differed by
at least two characteristics, the presence or absence of serifs and variable
versus constant stroke thickness. In addition, the study showed RSVP
reading speed to be affected at a low luminance condition for the two fonts
(both proportionally spaced and matched x-height).
Campbell K, et al /
CNIB research
report
2005
Grey (unpublished
scientific report)
Canada
398 (over
two experiments)
A two-phased study on the readability and legibility of six typefaces was
conducted with subjects having a primary diagnosis of AMD. Phase I
investigated preference of typeface for readability and Phase II tested the
readability of fonts in OTC medication labelling and inserts. Using rating
and ranking scales, all subjects, across the two experiments preferred the
font Adsans (a sans serif font originally used with metal typesetting, for
classified advertising, due to its good readability at extremely small point
sizes).
Perera S 2001
Grey (unpublished
scientific report—5
experiments)
England
308 (total
over 5
experiments)
Five experiments were conducted to determine the legibility of fonts,
specifically Tiresias, a new typeface for large print. Additional experiments
included serif/sans serif legibility, space and weight, punctuation, and serif
and space. Results were in favour of Tiresias, which was viewed as being
more legible than Times or Arial. Subjects with poor reading vision
preferred Tiresias more than individuals with fair or good reading vision.
Morris RA, et al
1991
Case series
USA
Yager D, et al 1998
Case series
USA
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Conclusions
In summarizing our review of the research on typeface characteristics, we can clearly state that the
choice of typeface and specific typographical features affect legibility for individuals with low vision
conditions where reading is a challenge. It is a well-known and accepted fact that typeface affects
legibility and readability (Tinker, 196338; Mackeben 199969; Mansfield, et al 199630; Roethlein, 191270;
Whittaker, et al 198948). However, it has only been within the last decade or so that computers are
able to provide researchers with better control over the typeface design characteristics being used
their research. Font modifications are at times necessary for experimental research and this is
possible as a result of the development of computerized fonts. Yesterday’s typeface designers and
printers had to go through an arduous process of changing letter features starting from drawings,
producing metal type, combining them to form words, and then printing them on paper. Today’s
designer can change any element of a typeface instantly using type design software, on a computer
and then immediately use the modified font to test the efficacy of the modifications by goal-directed
psychophysical experiments.71
Yet, even with the advent of advanced font technology and the manipulation of typeface
characteristics, the amount of research in this area is limited. The following conclusions are based
primarily on evidence from case series designs with small sample sizes, and an absence of separate
controls (internal controls are present in some cases). It is therefore impossible to make strong
evidence-based conclusions based on the existing research on font legibility and typographical
features for low vision readers. However, there are consistent threads that run through many of the
studies, in addition to solid, historical evidence supporting basic theories of typeface legibility.
Although the sound, historical evidence from previous typographical research oftentimes does not
take into account a visually impaired population, the main concepts and effects of this evidence can,
for the most part, be generalized to readers with low vision.
Choice of Typeface and Size
In one of the few quantitative studies on reading performance and font legibility for the visually
impaired, Mansfield, et al (1996), found a small, but significant advantage of Courier over Times
Roman in reading acuity, critical print size, and reading speed. However, gains in reading speed for
subjects with low vision were modest. It is possible however that for print sizes close to the acuity limit
the choice of font could make a significant difference in reading performance (for both normal and low
vision). Arditi (2004) found that prototype font adjustment software (Font Tailor) used in their
experiment produced enhanced legibility (gain averaged over 75%). The study did not demonstrate
any advantage—or increases in legibility—over standard fonts such as Times New Roman. Yager, et
al (1998) found that out of 20 subjects with normal vision, 16 subjects could read the Swiss, sans serif
font, more rapidly than the seriffed Dutch typeface. In this study, the lower-case x-height of the fonts
was approximately 5.5 times as large as letter acuity; the acuity reserve for Swiss was higher than for
Dutch at the low luminance, which may have accounted for the difference in reading speeds.
In a series of experiments comparing the customized Tiresias large print typeface to other fonts such
as Arial and Times Roman, Perera (2001, unpublished scientific report) found that in almost all of the
trials that subjects preferred the large print typeface, Tiresias over Arial or Times. Subjects with poor
reading vision preferred Tiresias more than individuals with good vision in experiments comparing
legibility (serif and typeface), space and weight of typeface, and punctuation. In addition, Campbell, et
al (2005, unpublished scientific report) reported that across a total of 398 participants, a 16-point sans
serif font called “Adsans” was found to be more readable than Times Roman, indicating that
familiarity with a popular font (Times Roman) did not correlate with preference for legibility or
readability. Chung, et al (1998) measured the effect of print size on reading speed in normal
peripheral vision. The results show that a larger print size was required to achieve maximum reading
speed in peripheral than in central vision.
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Drummond, et al (2004), Estey, et al (1990), and Campbell, et al (2005) all investigated the
relationship between text size and printed health information (medication labelling and patient
literature). Drummond observed that subjects with a best-corrected VA lower or equal to 6/24,
showed a significantly diminished ability to read instructions on their eye drops bottles. Subjects in
this study preferred Arial font with point sizes ranging from 16-22-pt, according to varying acuity
levels. Estey, in a study on patient literature for potential cataract patients found that 65% of subjects
found the Universe 14-pt. typeface to be the most legible, compared to a seriffed font, Century
Schoolbook. These patients also preferred the high contrast reading materials, with black text and a
white background. Campbell, et al showed that in comparing six different fonts in 7-point size on
sample OTC medication inserts and labels, that the preferred typeface was the sans serif font
(Adsans). These studies certainly lean in the direction of sans serif typefaces as being the most
preferred fonts regarding the readability and legibility of printed medical information and drug labels.
On the other hand, it is also evident that based on the results of the small sample of studies assessed
in this review, more research on the size and choice of typeface for medication labelling and patient
literature is needed. Based on the studies selected for this review, the choice of typeface has been
shown to affect reading speed and performance. Furthermore, it has also been shown that in some
cases, increased typeface legibility may have more to do with personal preference and individual
comfort than other conditions.
Serifs or Sans Serifs
Based on results from existing studies, the effects of the presence or absence of serifs on text
legibility seem to be inconclusive. Arditi & Cho (2005) as well as Moriarty & Scheiner (1984) found no
differences in reading speed when comparing sans serif to serif fonts. Arditi (2005), using nine
different, lower-case, customized fonts, found an extremely small effect of serif size in one of the
experiments. With very small letter sizes, close to the acuity limit, serifs may actually interfere, though
very slightly, with legibility. However, there was no strong determination of a definite difference in
legibility between serif and sans serif fonts. Morris, et al (2002) found that when comparing 4-pt. and
16-pt. Lucida fonts, serifs appeared to interfere only at very small sizes, and provided nothing toward
a sentence-based word recognition, through RSVP reading. They concluded that serifs may slow
RSVP reading at very small retinal sizes, and may be counterproductive. However, as stated above,
both Yager, et al (1998) and Perera (2001) found both increased reading performance and
preference for sans serif fonts (Swiss and Tiresias, respectively). Campbell, et al (2005) reported a
preference for sans serif fonts, as determined by readability rating and ranking tasks.
Letter Spacing or Crowding
Letter spacing or “crowding” has been shown to affect reading speed. Indeed, closely packed small
letters are much harder to read compared to the same letters presented in isolation.26 Most of the
knowledge on the “crowding effect” comes from letter identification experiments where the observer
either knew which letter in the display was the target or knew how many letters they were supposed
to report from a stimulus string.26 The effects of interletter spacing, stroke width, and letter aspect ratio
on legibility have all been studied. Arditi, et al (1990) found that for small characters, a fixed width
pitch produced the fastest reading. RSVP reading showed that higher text density and lower eye
movement requirements of variable width text is responsible for superiority at medium and large
character sizes. In an experiment conducted with normal vision subjects, Chung (2002) found that
increased letter spacing beyond the standard size does not lead to an increase in reading speed in
central or peripheral vision. Liu and Arditi (2000, 2001) observed under narrow-spacing conditions,
that random guessing and lateral interactions between features of neighbouring letters accounts for
most of the acuity deterioration. They also found that when information about the length of letter
strings is uncertain, subjects tend to underestimate the lengths of small, closely packed letter strings.
Typically, the subjects omitted one of the interior letters or combined two neighbouring letters under
these conditions. Moriarty & Scheiner (1984) found that the difference in mean words read between
close-set type and mean words read set in regular type was significant for the close-set type effect.
However, they could not support their hypothesis that the interaction between letter spacing and
typeface affects reading speed.
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Letter Confusion
People with central vision loss must often rely on eccentric viewing strategies. One of the goals of low
vision rehabilitation is to optimize the presentation of reading material for people with foveal vision
loss. It has been hypothesized that by optimizing conditions for letter recognition reading performance
with eccentric viewing may be enhanced. Some studies have sought to investigate this concept by
studying letter recognition tasks and analyzing letter recognition errors—or “confusions.” MacKeben
(2000) found that with six, normally sighted subjects, the most frequently confused letter pairs varied
between individuals. If one feature is modified in each of two out of ten frequently confused letter
pairs, the mean recognition performance could be improved significantly. Liu and Arditi (2000) found
that subjects made more mistakes in judging the number of letters in the stimulus strings as interletter
spacing decreased. Liu and Arditi (2001) showed that there were particular common letter confusions
for both narrow and wide letter spacings, as well as confusions that were unique to either narrow or
wide spacings. They conclude that the deterioration of legibility during narrow spacing conditions
could be attributable to an increase in random errors and a set of letter confusions not observed
under wide spacing conditions.
Psychophysics of Reading Experiments
Gordon Legge and colleagues conducted a series of experiments on the psychophysical factors that
may or may not affect reading. The series of twenty studies included subjects with both visual
impairment and normal vision and investigated a number of factors associated with reading and text
characteristics. In this review, we decided to assess only those Psychophysics of Reading studies
that directly confronted issues surrounding specific typefaces, legibility and characteristics associated
with low vision. Many of the Psychophysics of Reading of studies investigated elements of
typography and associated characteristics such as size, contrast, blur, crowding, and letter confusion,
in conjunction with other main hypotheses, such as linking letter recognition to the visual span or
page navigation with magnifiers. It is evident that many of these characteristics are important
considerations for low vision conditions. Blur, for example plays an important role in several forms of
low vision: cataract, keratoconus, and corneal scarring. Blur can limit reading performance and
research72 on this subject shows that in order to be legible, bandwidths in the range of 1.5-3 cycles
per character width are required.5 In this series, a study on the effects of wavelength (text colours)
showed that subjects with low vision, and in particular, degenerative diseases of the photoreceptors,
showed a tendency to read better with blue, rather than red. Legge and Rubin (1986) 73 found that the
presence of central or peripheral field loss in not predictive of wavelength effects in reading. On the
whole, they found that wavelength, only occasionally plays a role in reading performance.
In summary, it is clear from the research and this review, that the choice of typeface and its
associated characteristics can all impact legibility and reading performance for individuals with
various low vision conditions. In terms of which font style and typeface characteristics are the best for
reading performance, some of this has been proved scientifically, while other aspects of text legibility
appear to be dependent upon individual preferences. In other cases, it just seems to be an issue of
“common sense.” For example, you wouldn’t intentionally reduce the space between letters to the
point of illegibility on a marketing brochure, nor would you write your graduate thesis in a red with a 4point font. Current guidelines on good design for printed materials for people with visual impairment
are extremely beneficial, and there appears to be increasing enlightenment on the part of the nonvisually impaired community and public and private organizations to keep pace with these
developments. With the advent of the Internet and computer-related technologies, issues surrounding
information accessibility are well developed and gaining momentum. It is perhaps, only a matter of
time before standardized concepts on text legibility for the visually impaired are instituted on both a
local and global scale.
 VREBR Project Team and CNIB Research
24
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April 2006
References
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Tinker M. Legibility of print. Ames Iowa: Iowa State University Press. 1963.
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Arditi A. Typography, print legibility and low vision. In: B. Rosenthal and R. Cole (eds.),
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Berger C. Stroke-width, form, and horizontal spacing of numerals as determinants of the threshold
of recognition I. Journal of Applied Psychology 1944;28:208-231.
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Berger C. Stroke-width, form and horizontal spacing of numerals as determinants of the threshold
of recognition II. Journal of Applied Psychology 1944;28:336-346.
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Arditi A, Cagenello R and Jacobs B. Effects of aspect ratio and spacing on legibility of small letters.
Supplement to Investigative Ophthalmology and Visual Science 1995;36:671.
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Berger C. Experiments on the legibility of symbols of different width and height. Acta
Ophthalmologica 1948;26:423-434.
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Soar RS. Height-width proportion and stroke width in numerical visibility. Journal of Applied
Psychology 1955;39:43-46.
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Arditi A, Liu L, and Lynn W. Legibility of outline and solid fonts with wide and narrow spacing. In: D.
Yager (ed.) Trends in Optics and Photonics. Washington, DC: Optical Society of America. 1997.
47
Moriarty SE and Scheiner EC. A study of close-set text type. Journal of Applied Psychology
1984;69:700-702.
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Whittaker S, Rohrkaste F and Higgins KE. Optimum letter spacing for word recognition in central
and eccentric fields. Noninvasive Assessment of the Visual System, Technical Digest Series 7.
Washington, DC:Optical Society of America, pp.56-59. 1989.
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Arditi A and Cho J. Serifs and font legibility. Vision Research 2005;45:2926-2933.
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Cline D, Hofstetter HW, Griffin , JR (eds.) Dictionary of Visual Science. 4th ed. Boston
MA:Butterworth-Heinemann; 1997:521.
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Chung ST. The effect of letter spacing on reading speed in central and peripheral vision. Invest
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Rubin GS and Turano K. Reading without saccadic eye movements. Vision Research
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Morris R, Aquilante K, Yager D & Bigelow C. Serifs slow rsvp reading at very small sizes, but don’t
matter at larger sizes. Society for Information Display International Symposium Digest of Technical
Papers 2002;33(1):244-247. Retrieved April 10, 2006 from:
http://www.cs.umb.edu/~ram/rsvp/publications/SerifsSubmittedV2.doc
53
54
For a complete list of the publications in this series, see:
http://gandalf.psych.umn.edu/~legge/series.html
55
See: http://vision.psych.umn.edu/~gellab/
 VREBR Project Team and CNIB Research
27
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56
Colenbrander A. Visual Standards—Aspects and Ranges of Vision Loss. Report prepared for the
International council of Ophthalmology at the 29th International Congress of Ophthalmology. 2002.
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See: http://www.ifla.org/
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Kavanagh R and Sköld B (eds.). Libraries for the Blind in the Information Age, Guidelines for
Development. International Federation of Library Associations and Institutions. IFLA Professional
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Canadian Library Association. Opening the Book: A Strategy for a National Network for Equitable
Library Service for Canadians with Print Disabilities. September 2005. Ottawa. Retrieved on March
29, 2006 from: http://www.cla.ca/issues/nnels_final.htm
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See: http://www.lighthouse.org/default.htm
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See: http://www.aph.org//edresearch/lpguide.htm
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See: http://www.tiresias.org/index.htm
63
See: http://www.tiresias.org/reports/subject.htm
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Over-the-Counter Human Drugs; Labeling Requirements. U.S. Department of Health and Human
Services, Food and Drug Administration. Rockville, MD. January 4, 1999. See:
http://www.fda.gov/cder/otc/label/cd9845.pdf
65
Canadian Public Health Association. Good Medicine for Seniors: Guidelines for Plain Language
and Good Design for Seniors. 2002. See: http://www.nlhp.cpha.ca/Labels/seniors/english/cover.htm
66
Nonprescription Drug Manufacturers Association of Canada. NDMAC Technical Research Paper
for Improving Label Comprehension. 2006. See:
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Page=9
67
Drummond SR, Drummond RS, Dutton GN. Visual acuity and the ability of the visually impaired to
read medication instructions. Br J Ophthalmol 2004; 88(12):1541-1542.
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Canadian Task Force on the Periodic Health Examination: The periodic health examination. CMAJ.
1979;121:1193-1254.
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Mackeben, M. (1999) Typefaces influence peripheral letter recognition and can be optimized for
reading with eccentric viewing. Paper presented at the Vision 99, New York, NY.
70
Roethlein BE. The relative legibility of different faces of printing types. The American Journal of
Psychology 1912; 23(1):1–36.
71
MacKeben M. Enhancement of peripheral letter recognition by typographic features. Vis Impair Res
2000;2(2):95-103.
72
Ginsburg AP. (1978) Visual Information Processing Based on Spatial Filters Constrained by
Biological Data. Vols. I and II, Ph.D. thesis, Cambridge University, in Aerospace Medical Research
Laboratory Report AMRL-TR-78-129, Wright-Patterson AFB, OH.
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73
Legge G and Rubin GS. Psychophysics of Reading IV—Wavelength effects in normal and low
vision. 1986 J Opt Soc Am;3(1):40-51.
 VREBR Project Team and CNIB Research
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April 2006
Appendix I—Studies and Publications Selected for Review
1. Arditi A and Cho J. Serifs and font legibility. Vision Research 2005;45:2926-2933.
2. Arditi, A. Adjustable typography: An approach to enhancing low vision text accessibility.
Ergonomics 2004;47(5):469–482.
3. Arditi A, Knoblauch K, & Grunwald I. Reading with fixed and variable character pitch. Journal of
the Optical Society of America 1990;A (7):2011–2015.
4. Campbell K, et al. CNIB/OCAD typographic legibility research project—“Clear Print” report. May
2005. CNIB Research.
5. Chung ST. The effect of letter spacing on reading speed in central and peripheral vision. Invest
Ophthalmol Vis Sci 2002; 43(4):1270-1276.
6. Chung STL, Mansfield JS, Legge GE. Psychophysics of reading. XVIII. The effect of print size on
reading speed in normal peripheral vision. Vision Research 1998; 38(19):2949-2962.
7. Drummond SR, Drummond RS, Dutton GN. Visual acuity and the ability of the visually impaired
to read medication instructions. Br J Ophthalmol 2004; 88(12):1541-1542.
8. Estey A, Jeremy P, Jones M. Developing printed materials for patients with visual deficiencies. J
Ophthalmic Nurs Technol 1990; 9(6):247-249.
9. Liu, L., & Arditi, A. How crowding affects letter confusion. Optometry and Vision Science 2001;
78:50-55.
10. Liu, L., & Arditi, A. Apparent string shortening concomitant with letter crowding. Vision Research
2000;40:1059-1067.
11. MacKeben M. Enhancement of peripheral letter recognition by typographic features. Vis Impair
Res 2000;2(2):95-103.
12. Mansfield JS, Legge GE, & Bane MC. Psychophysics of reading Xv: Font effects in normal and
low vision. Investigative Ophthalmology and Visual Science 1996; 37(8):1492–1501.
13. Moriarty SE and Scheiner EC. A study of close-set text type. Journal of Applied Psychology
1984;69:700-702.
14. Morris R, Aquilante K, Yager D & Bigelow C. Serifs slow rsvp reading at very small sizes, but
don’t matter at larger sizes. Society for Information Display International Symposium Digest of
Technical Papers 2002;33(1):244-247. Retrieved March 31, 2006 from:
http://www.cs.umb.edu/~ram/rsvp/publications/SerifsSubmittedV2.doc
15. Morris RA, Berry K, Hargreaves KA, Liarokapis D. How typeface variation and typographic
scaling affect readability at small sizes. Society for Imaging Science and Technology, Portland:
Proceedings of the 7th International Congress on Advances in Non-Impact Printing Technologies,
1991.
16. Perera S. An investigation into the legibility of large print typefaces. December 2001. RNIB
Scientific Research Unit. Retrieved March 24, 2006 from
http://www.tiresias.org/fonts/lpfont/report/index.htm
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17. Yager, D., Aquilante, K., & Plass, R. High and low luminance letters, acuity reserve,and font
effects on reading speed. Vision Research 1998;38:2527-2531.
 VREBR Project Team and CNIB Research
31
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April 2006
Appendix II—Study Attributes Table
The following table contains data extracted from the studies selected for review and is listed alphabetically by first author’s last name.
Study Attributes
Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Case series
Arditi A & Cho J
2005
USA
Three experiments
using nine custom
fonts, to determine
the legibility of serifs
and sans serif fonts
(0%, 5%, and 10%
cap height).
Case series
Arditi A 2004
USA
Adjustable typography
using Font Tailor
software prototype.
Nine
customized,
lower-case fonts
varying in serif
size (0%, 5%,
and 10% cap
height).
 Customized
font using
FontTailor
program
(default cap
height 38 mm,
162 point)
 Times New
Roman
(initially set on
monitor at 18
point size)
 VREBR Project Team and CNIB Research
Normal vision (n=2)
AMD (n=2)
4
No other characteristics
reported.
40
Various ocular pathologies,
mainly AMD, cataract,
glaucoma, and DR.
20/40 or worse
Difficulty with reading
Outcomes Measured, Evaluation
and Statistical Methods
 Legibility of serif or sans serif
fonts using size threshold
measures (experiment 1), RSVP
reading (experiment 2), and
continuous reading on paper
(experiment 3).
 All text was presented on a
computer monitor, with black text
on white background.
 ANOVA (for all analyses)
 Font parameter adjustments
(according to subject)
 Parameters tested were letter
spacing, stroke width, serif size,
x-height, and aspect ratio.
 Font Tailor program and 19-in.
display monitor centered at eye
height, viewed from a distance at
which the default font (cap
height 38mm, font size 162
point) could be read comfortably.
 Text displayed in black letters on
white background.
 Reading acuity with Times New
Roman—to compare with
adjustments made to Font Tailor
fonts.
 Measurements made with
Results or Findings
 In experiments 2 and 3, the
presence or absence of serifs
made no difference in reading
speed, for all participants, both
normally sighted and low vision.
 In experiment 1 a statistical effect
of serif size was observed,
although this difference was
extremely small.
 The authors conclude that with
very small letter sizes, close to the
acuity limit, serifs may actually
interfere, though very slightly, with
legibility.
 Participants varied widely on in the
font that produced the most legible
text.
 All participants reading acuities
improved with the adjusted font.
 Manipulation of inter-letter spacing
had the largest impact on legibility
(almost 20% smaller characters
could be read than with the default
font spacing).
 Manipulation of the x-height and
aspect ratio also resulted in
substantial gains in legibility.
 The smallest gain was seen for the
manipulation of serif size.
 The most significant gain from this
experiment was the total legibility
gain from all adjustments,
32
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April 2006
Study Attributes
Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Lighthouse/ETDRS chart.
 Box and whisker plots showing
upper, lower, and interquartile
range of distributions.
Case series
Arditi A,
Knoblauch K, &
Grunwald I.
1990
USA
To determine the
effect of pitch
(variable and
proportional spacing)
on reading speeds at
various character
sizes. A control
experiment was
conducted using
RSVP reading.
 Times Roman
 Fixed-width
version of
Times Roman
(customized by
the
experimenters)
 18 point
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
4
Authors served as subjects.
All subjects had normal
vision.
One was colour defective.
 Reading performance (rate and
accuracy)
 Testing blocked by character
size, with the set of character
sizes run in pseudo-random
order. Within character size, the
three text display conditions
were pseudo-randomly
permuted.
 Text broken into lines consisting
of the largest number of whole
words that could fit into a 35
character line.
 Experiment 1: Reading with free
eye movements, variable width
(VW), fixed width (FW), and
modified variable width (MVW)
characters.
 Experiment 2: RSVP reading,
identical to experiment 1.
 Experiment 3: Eccentric reading
without eye movement
requirements.
 Data was presented graphically,
with error bars, showing reading
rate as a function of character
size. Each point on the graph
represented the geometric mean
of at least 6 measurements.
 Measurement of RSVP reading
Results or Findings
averaged 75%.
 For a broad range of visual
acuities, the adjusted font and
Times New Roman were almost
identical for legibility.
 VW pitch yielded better
performance at medium and large
character sizes.
 FW pitch was superior for
character sizes approaching the
acuity limit.
 Crowding effects were noted at the
smallest sizes (character and word
identification).
 The control experiment with RSVP
reading suggested that reduced
eye movement requirements of
variable pitch contribute to the
superiority at medium and large
character sizes.
 For unscrambled text, the
difference was greater than zero,
indicating the original effect that
FW text is read faster than MVW
text.
 At the character heights measured,
FW text was read on average
about 28% faster than MVW text.
 For scrambled text, differences
between reading speed were
reduced to near zero.
33
Clear Print
April 2006
Study Attributes
Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
rates with 2 deg eccentric
viewing. As a fixation control,
words were presented randomly
either 2 deg above or below a
fixation point to discourage eye
movements to an unexpected
word location.
 Reading performance compared
for MVW and FW text using
scrambled text—to evaluate
whether the added inter-word
space of the MVW text
influenced reading by interfering
with comprehension [expressed
through difference of logarithms
of reading rates for FW and
MVW text for scrambled and
unscrambled text].
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
34
Clear Print
April 2006
Study Attributes
Study
Study Design and
Methods
Grey (unpublished
scientific report and
study)
Campbell K,
et al/CNIB
research report
2005
Canada
2-phased study to
determine font
legibility and user
preference using six
typefaces. Phase I
included rating and
ranking tasks for six
fonts. Phase II tested
font readability in
OTC and prescription
drug labels and
inserts.
Fonts Used
Phase I
(all 16-point) and
Phase II
(all 7-point):
 Adsans
 Arial
 Clearview
 Lucida
 Times Roman
 Verdana
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
N
Phase
I=241
Phase
II=157
Subject Characteristics
Phase I
 AMD (primary diagnosis, all
subjects)
 Secondary diagnoses:
myopia, presbyopia,
cataracts, astigmatism,
drusen, amblyopia.
 Age range = 51-85.7 yrs.
 Mean age = 77.4 yrs.
 Female (71%)
 Participants were recruited
from Edmonton, Toronto,
and St. John’s,
Newfoundland
Phase II
 AMD (primary diagnosis, all
subjects)
 Secondary diagnoses:
myopia, presbyopia,
cataracts, astigmatism,
drusen, amblyopia.
 Age range = 52.9-85.5 yrs.
 Mean age = 78 yrs.
 Female (70.1%)
 Participants were randomly
selected from CNIB
databases with AMD.
 Subjects were from the
greater Toronto region.
Outcomes Measured, Evaluation
and Statistical Methods
Phase I
 Rating task: Font readability
scale from 1 (impossible to read)
to 7 (very easy to read).
Directions were written in 16point font.
 Each participant was randomly
assigned a package containing
six pages, each with a different
typeface.
 All fonts were in 16-point font
and presented in random order.
 6 passages of text from Robert
Louis Stevenson’s Treasure
Island.
 Subjects were able to use
magnifiers, if needed.
 Ranking task: Subjects were
asked to place samples of text in
order from the easiest to the
hardest to read.
Phase II
 Rating task: Font readability
scale from 1 (impossible to read)
to 7 (very easy to read).
 Packaging contained six mockups of instructional OTC drug
inserts in six different fonts, at 7pt. size. Exact pairing of the
insert and font, and order in
which they were viewed was
randomized.
 Participants were allowed to use
reading aids of their choice. A
CCTV, lamp, and magnifiers
were available.
 Ranking task: Subjects were
asked to rate each font, one at a
time, using the seven-point
rating scale.
Results or Findings
Phase I
 The typefaces differed significantly
in their readability (p<0.05).
 Adsans was the most readable
typeface.
 Results from a CNIB font
preference survey (using Adsans
and Century Schoolbook)
confirmed the results: out of 470
respondents, 94% preferred the
Adsans font.
Phase II
 The typefaces differed significantly
(p<0.05) in readability.
 Adsans was the most readable
typeface for all participants.
 Most participants chose the CCTV
as the LVA of their choice (66%).
 A separate analysis was completed
to compare readability among the
CCTV users and non-CCTV users:
The CCTV users reported higher
levels of readability in general and
rated the readability of the font
Verdana more readable than Arial
and Lucida. Non-CCTV users
found Lucida more readable than
Verdana and Arial.
35
Clear Print
April 2006
Study Attributes
Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Case series
Chung S 2002
USA
To determine if
reading speed could
be increased with
increased letter
spacing, using
psychophysical
methods and RSVP
reading. Also tested
was whether letter
spacing imposes
limits on small or
large size print.
Courier (fixed
width font)
presented at
0.8x or 1.5x the
CPS
6
Normal vision
Case series
Chung S, et al
1998
USA
Measured the effect
of print size on
reading speed at
different retinal
eccentricities in
normal peripheral
vision.
Times Roman on
computer
monitor with
eight print sizes
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
6
 College-age with normal
vision, all had corrected VA
of 20/20 (range 20/13—
20/20).
 No prior experience with
RSVP reading technique.
Outcomes Measured, Evaluation
and Statistical Methods
 Psychophysical methods for
determining reading speed.
 RSVP reading
 High contrast text was displayed
black on white, on a computer
monitor.
 Three retinal eccentricities 0,
5, and 10 in the inferior visual
field tested.
 Two print sizes: 0.8 and 1.5 the
CPS.
 ANOVA (repeated measures)
 Geisser-Greenhouse adjusted
 Reading speed at various
eccentricities in normal
peripheral vision, at eight print
sizes (spanning ~0.7 log units).
 RSVP reading utilized in
experiment
 “Scaling hypothesis”—reading
speeds should remain invariant
with eccentricity, as long as print
is appropriately scaled in size.
 Reading speed measured with
single sentences extracted from
nine novels. Sentences were
chosen randomly for each trial.
 Words were in Times New
Roman, proportionally spaced
font, high contrast black letters
on white background and
displayed on computer screen.
 Criterion reading speed was
derived using psychometric
methods.
 Video-based eye tracking was
used to ensure observers fixated
properly, so text would be
presented at the intended retinal
Results or Findings
 Reading speed was highest at the
fovea, decreased with eccentricity,
and was faster for the larger print
size.
 At all eccentricities, and for both
print sizes, reading speed
increased, up to a critical letter
spacing, and either remained
constant at the same reading
speed or decreased slightly for
larger letter spacings.
 Increased letter spacing, beyond
the standard size, does not lead to
an increase in reading speed in
central or peripheral vision.
By determining reading speeds as a
function of print size at six different
retinal eccentricities the results
showed:
 Larger print size is required to
achieve maximum reading speed in
peripheral than in central vision.
 The rate of change in reading
speed as a function of print size
remains invariant in central and
peripheral vision.
 Even when print size is not the
limiting factor, maximum reading
speeds are still lower in peripheral
than in central vision.
36
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Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
eccentricity.
 ANOVA (repeated measures)
 Cumulative Gaussian curve
(psychometric functions)
Case series (subjects
randomly selected)
Drummond SR,
et al 2004
Scotland
 Reading medication
instructions (labels)
 Subjects were
randomly selected
from patients
attending Tennent
Institute of
Ophthalmology,
Glasgow.
Arial (16-22 point
sizes)
180
Glaucoma (25%)
AMD (19%)
Retinal/macular pathology
(11%)
Cataract (11%)
DR (12%)
Unspecified (6%)
Corneal (6%)
Congenital condition (3%)
Vascular event (3%)
Optic neuropathy (2%)
Uveitis (2%)
VA range: 6/9 – 6/60 (some
ability to read medication
bottles)
Mean age = 70 yrs.
Age range = 23-100 yrs.
 Reading instructions on bottle of
eye drop medication.
 Subjects grouped by bestcorrected VA (ranging from
6/9—6/60).
 Near VA assessed using Snellen
and near vision cards.
 Subjects read the instructions on
the side of the box and stated
their preference of font size from
a standard selection.
 Statistical analysis performed
with Kruskal-Wallis
 Dunn’s test (to compare each
group)
 P value of <0.05 considered
significant.
 Subjects with best-corrected VA of
lower than or equal to 6/24 showed
a significantly diminished ability to
read the instructions on their eye
drops bottles (p<0.001 for each
comparison).
 Subjects preferred Arial font sizes.
Point size preference was 16 for
6/24 group, 18 for 6/36 group, and
22 for 6/60 group.
Male (43%)
Female (57%)
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
37
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Study
Study Design and
Methods
Case series
Estey A,
Jeremy P and
Jones M 1990
Canada
Font type, size, and
colour regarding
patient hospital
literature, were all
evaluated for
preference by
subjects admitted for
cataract surgery at an
in-patient
ophthalmology unit.
Fonts Used
 Universe
medium
12- point (sans
serif)
 Universe
medium
14-point (sans
serif)
 Century
Schoolbook
14-point (serif)
N
52
Case series
Liu L and Arditi
A. 2001
An analysis of the
types of acuity errors
made using varying
interletter spacing.
Errors were analyzed
using a “letter
confusion matrix.”
METAFONT,
font design
language (fixed
pitch font)
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
 Patients who had been
admitted for cataract
surgery
 Average age = 69.4 yrs.
 Female (27), Male (25)
 Reading of patient hospital
literature preference using
comparisons of font, point size,
serif/sans serif, and colour.
 Colours used in experimental
pamphlets: Pantone Colour
system: PMS 349 Green,
Process Blue, and Black.
 No statistical analyses reported.
 65% of the patients could read the
12-pt. typeface, 35% found it
blurry.
 65% preferred the Universe (sans
serif) typeface.
 33% preferred Century Schoolbook
(serif).
 2% had no preference.
 Black ink was preferred by 73% of
patients.
 Five-letter word strings randomly
drawn from the 26 uppercase
letters of the English alphabet.
 The overall height and width of
the letters were five times the
width of the strokes.
 Compared letter confusions
obtained at a wide (1.0 letter
height) and narrow (0.1 letter
height) interletter spacings.
 Each interletter spacing
condition tested with a total of
260 random five-letter strings
broken into five balanced
sessions.
 Letter strings presented on
computer monitor.
Statistical analyses:
 Letter confusion matrices
 Spearman’s rank correlation
(relative legibility)
 Common letter confusions:
statistically significant confusions
that were common to both wide
and narrow letter spacings,
examples included FP, QG,
GO, VY, IZ, and YT.
 For narrow spacing, common
confusions: FP, YT, VY,
QG, GO, and IZ.
 Unique confusions under narrow
spacing confusions: UL, UJ,
DC, RP, JL, and EB.
 Letter confusions are qualitatively
and quantitatively different under
wide and narrow spacing
conditions.
 The deterioration of legibility during
narrow spacing conditions could be
attributed to an increase in random
errors and occurrence of a set of
letter confusions not observed
under wide-spacing conditions.
Author of this paper (n=1).
Naïve volunteers from
Lighthouse International
(n=3)
4
All subjects had normal or
corrected-to-normal vision.
Age range 20-40 yrs.
38
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Study
Study Design and
Methods
Fonts Used
N
Case series
Liu L and Arditi
A. 2000
Participants were
asked to identify
letters in randomly
presented four-letter
and five-letter strings.
METAFONT,
font design
language (fixed
pitch font)
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
3
Subject Characteristics
All subjects had corrected-tonormal vision. Distance
corrections worn during
experiments.
Age= all participants in 20’s
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
 Four interletter spacings used:
0.04, 0.08, 0.16, and 0.24 letter
height.
 Letters in the interior of each
string were restricted to a set of
five letters: A, J, L, N, U.
 60 five-letter strings and 20 fourletter strings used.
 The letter height range for all
three participants was 1.0 and
1.44cm (45-65 pixels).
 Letters presented at high
contrast and on a computer
monitor.
“Crowding effect”:
 The greatest errors of at least 30%
at the narrowest interletter spacing
(0.04 times of the letter height).
 When the spacing increased to
0.24 times of the letter height (the
widest spacing), the subjects
correctly identified most of the
letters. The deterioration of
legibility at narrower spacings
indicates interaction between
neighbouring letters, i.e. a
“crowding effect.”
Errors in judging string length:
 As interletter spacing decreased,
observers made more mistakes in
judging the number of letters in the
stimulus strings.
 Errors were categorized into three
main types of errors: In-place
errors—letters mistaken for other
letters without disturbing
neighbouring letters. Omission of
interior letters—four out of five
letters of a five-letter string were
correctly identified but one of the
letters was missing. Merger of
neighbouring letters—sometimes,
two neighbouring letters were read
as one letter, which combined the
strokes of the two stimulus letters,
example: JJLUPJAUP,
XJUALKANL, NNALTWALT,
and QJAUCQJNC.
 Conclusion: when information
about the length of letter strings is
uncertain, observers tend to
underestimate the lengths of small,
closely packed letter strings.
Typically, the observers tend to
39
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Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
omit one of the interior letters or
combine two neighbouring letters
under such conditions.
Case series (included
pilot data)
MacKeben M.
2000
USA
Experimental strategy
to improve peripheral
letter recognition by
modifying
typographical design
features based on
psychophysical data.
Arial Bold
6
All had normal vision
Correctable refractive errors
(20/50 or better)
Ages: 23, 24, 29, 52, 55, 58
yrs.
 Psychophysical testing, data
analysis of letter confusion
matrices, letter modification of
most frequently confused letter
pairs using font design software.
 Pilot data from previous
experiment, and
 10 single letters of Sloan (C, D,
H, K, N, O, R, S, V, Z) set in
Arial typeface, displayed at
eccentricity of 8 on a computer
monitor.
 Target duration was adjusted
individually (66-133 ms, all
integral products of a single
frame duration of 16.5 ms) to
operate the task near threshold.
 Letter height was 36 arcmin—
well above the size threshold at
this eccentricity and contrast.
 Viewing binocular at 91 cm.
Data Analysis:
 Letter confusion matrices with d’
ratings.
 Paired t-tests
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
 The confusion matrices for
unmodified Arial Bold showed that
OD and HN belonged to the
three most frequently confused
pairs for five out of six subjects.
 HN was the top of three in the
sixth subject.
 No other letter pairs came close in
the average number of confusions.
 It was concluded that modifying
one letter each out of these two
pairs would affect the overall
recognition rate the most.
 The modifications consisted of
doubling the width of the horizontal
stem of the “H” to make it less
confusable with “N” and adding
serifs to the “D” to make it less
likely to be confused with “O”.
 The mean recognizability was, on
average, improved by 18.7% by
modifying features of just two
letters in a set of 10.
 The individual mean differences
were statistically significant in a
paired t-test (p<0.001).
 Even with a small group of
subjects, the author concludes that
there were important interindividual
differences, and no generalized
assumptions should be made. This
40
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Study
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Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
suggests that an individual
assessment of problem letter pairs
and individual tuning of typefaces
might be necessary to secure good
performance for each individual.
Subjects with normal vision
(n=50) were undergraduate
psychology students.
Cohort
Mansfield JS,
Legge GE, and
Bane MC
1996
USA
§§
Reading acuity,
maximum reading
speed, and critical
print size (CPS) were
measured in 50
normal vision subjects
and 42 low vision
subjects. Data were
collected using
versions of MNREAD
chart printed with
Times (proportionally
spaced) and Courier
(fixed-width) fonts.
 Times-Roman
 Courier-Bold
92
Subjects with low vision
(n=42) diagnoses:
 Cataract, nystagmus,
corneal opacification, DR,
glaucoma, optic neuritis
(including ischemic and
atrophy), progressive
myopia, RP, ROP, AMD,
detached retina, juvenile
macular degeneration,
Leber’s disease, and optic
nerve deterioration.
 Some subjects had central
field loss.
Mean age and distance
acuities (SD):
 Intact central vision:
4111.2 yrs., 0.870.52
logMAR (20/148).
 Central vision loss: 6815.4
yrs., 0.850.35 logMAR
(20/148).
Outcomes Measured:
 Reading acuity, maximum
reading speed, and CPS (the
smallest print that can be read at
the maximum reading speed).
Evaluation Methods:
 MNREAD Acuity Chart with a
series of 19 sentences printed at
progressively smaller sizes.
 Each Times-Roman sentence
had 60 characters (including
spaces between words).
 Each Courier-Bold sentence had
56 characters.
Statistical or data analyses:
 Reading acuity was calculated in
a similar manner to the “letterby-letter” method described by
Ferris, et al§§
 Algorithm for calculating CPS,
which identifies the reading
speed plateau.
 Maximum reading speed was
defined as the geometric mean
of the reading speeds across the
plateau. CPS was defined as the
 Reading acuity scores obtained
with Courier were better than those
obtained with Times for both
normal (mean difference, 0.05
logMAR, P < 0.001) and subjects
with low vision (0.09 logMAR, P <
0.001).
 CPS measured with Courier were
smaller than those measured with
Times (mean difference, 0.06
logMAR for normal subjects and
subjects with low vision), P <
0.002).
 Maximum reading speeds for
normal subjects were 5% faster
with Times than with Courier (P <
0.001), but for subjects with low
vision, maximum reading speeds
were 10% slower with Times than
with Courier
(P < 0.05).
 For print smaller than the CPS, the
reading speeds of normal subjects
and subjects with low vision were
substantially slower (by as much as
50%) for Times than for Courier.
Ferris FL, Kassoff A, Bresnick GH, Bailey IL. New visual acuity charts for clinical research. Am J Ophthalmol 1982;94:91-96.
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
41
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Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
Results or Findings
smallest print size included in
the plateau.
 Pairwise t-tests
Cohort
Moriarty SE and
Scheiner EC.
1984
An investigation into
the use of close-set
type (interletter
spacing) and font
style: serif or sans
serif.
 Times Roman
(serif)
 Helvetica
(sans serif)
 Both with 11point type and
1-point
leading.
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
College students
260
Female (123), male (137)
No vision characteristics
reported.
 Four variations of copy style:
serif with regular spacing, serif
with close spacing, sans serif
with regular spacing, and sans
serif with close spacing.
 Measures of performance
included how many words were
read in a given time period.
 For the close-set passages of
text, the amount of minus
letterspacing was specified as
ten units of minus spacing (on a
54-unit base), equivalent to 18%
reduction in interletter spacing.
 Controlled group testing situation
where test messages were
distributed randomly by rotation.
 No explanation of statistical
methods, but F and p values
given.
 The difference in mean words read
between close-set type messages
(370.19) and mean words read for
messages set in regular type
(331.81) was significant for the
close-set main effect
F(1,256)=7.966, p<.005
(eta2=.026). This result supports
the authors’ hypothesis indicating
an advantage in reading speed
resulting from the use of close-set
type, for typefaces and letter space
variations used in this study.
 The difference in mean words read
between messages set in serif
typeface (352.31) and the mean
words read for messages set in
sans serif typeface (344.98) was
not significant at the .05 level. This
supports the hypothesis that there
is no difference in the use of serif
or sans serif typefaces in relation to
reading speed.
 With the third hypothesis—that the
interaction of letter spacing and
typeface does not affect reading
speed was supported. The
interaction of letter spacing and
typeface is not significant.
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Study Design and
Methods
Case series
Morris RA, et al
2002
USA
To determine the
effects of serifs on
RSVP reading
performance.
Case series
Morris RA, et al
1991
USA
How font quality might
influence conclusions
about typographic
variables and
readability. To test the
hypothesis that
previous conclusions
Fonts Used
Lucida (serifs
and sans serif
versions;
modified for the
experiment)
 Experiment
1:Times PFW
(Psuedo Fixed
Width) and
Times NSB
(No Side
Bearings),
modified
Macintosh
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
N
Subject Characteristics
No vision characteristics
reported.
27
Subjects were all native
English readers.
Three of the authors served
as subjects.
4
1 subject was naïve
typographically and to the
experiment’s purpose.
Outcomes Measured, Evaluation
and Statistical Methods
 Subjects viewed a screen in a
darkened room at 4m, resulting
in retinal x-heights of approx. 12
arc-minutes and 48 arc-minutes
of visual angle. This corresponds
to 4-point and 16-point type at
normal reading distance of
40cm.
 Staircase method was used to
estimate reading rates.
 Custom software presented
words serially on the display.
 Subjects initiated the next
presentation with a press of a
mouse button.
 Each subject repeated five trials
at two sizes and for two fonts
(serif and sans serif Lucida
variants).
 Number of words read correctly
per unit time was the accepted
measure of reading
performance.
 Sentences were artificially
constructed, but meaningful
English, unconnected to one
another, approx same length.
 Exponentiation resulting
confidence intervals provided an
estimate for the performance
advantage of the task with serif
or sans serif type.
 This study looked at fixed vs.
variable width fonts, typographic
v. linear scaling, and tight v.
loose letter spacing.
 Reading rate (computed as the
product of the percentage of
correctly read words and the rate
of text presentation in words per
minute).
Results or Findings
 For the 4-point faces, the
probability exceeds .95 that the
advantage of sans over seriffed
Lucida is between 1.16 and 1.24.
 For the 16-point face the probability
exceeds .95 that this ratio is
between .98 and 1.02.
 In summary, serifs interfere only at
very small sizes and provide
nothing toward sentence-based
word recognition as revealed with
RSVP reading.
 Successful rendering of serifs at
small retinal sizes may be
counterproductive.
 For most subjects there was little
significant difference between the
crowded NSB font and the
artificially spaced PFW font,
suggesting that letter spacing alone
cannot account for reading rate
differences.
 Loose letter spacing does not
make fonts easier to read. Rather,
43
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April 2006
Study Attributes
Study
Study Design and
Methods
drawn about fonts and
reading performance
may be irrelevant if
the fonts are properly
designed.
Grey (unpublished
scientific report and
study)
Perera S 2001
England
***
A series of five
experiments: typeface
legibility, serif
legibility, space and
weight of typeface,
punctuation legibility.
Exp 1-4 were withinsubjects designs and
the last was a mixed
within/between
subjects design.
Fonts Used
N
Subject Characteristics
 Readability was measured using
a “flash card” method.
 All experiments conducted on a
computer monitor.
 Sentences were broken into 2429 characters per line and text
was from one million English
words in the Brown Corpus of
English.
Times fonts;
12 and 24points.
 Experiment 2:
Poorly formed
fonts based on
Times.
 Lucida Sans
and
Typewriter, 12
and 24 points.
 Computer
Modern
Roman using
Metafont, 6
and 12-point
size.
 Exp 1:
Tiresias, Arial,
and Times
New Roman
 Exp 2: Tiresias
modified with
serifs and sans
serif
 Exp 3:
Tiresias,
altered for
varying
spacing
 Exp 4:
punctuation
 Exp 5:
samples from
text with
different
Outcomes Measured, Evaluation
and Statistical Methods
308***
Exp 1:
 Subjects’ rating of their
vision: poor vision (125),
fair vision (62), and good
vision (21).
 115 said they could not
read ordinary print and 96
replied they could.
 Mean age = 61.4 (SD 18.3)
 Female (137), male (79)
 Of 113 subjects, the mean
number of large print books
read per week was 0.80
(SD 0.88), with the max
being 3 and the min 0.
Exp 2:
 Self-rated measure of
vision: poor (13), fair (8),
good vision (0).
Exp 1 (for all subjects—
comparisons were also made for
current and potential readers of
large print):
 Questionnaire and samples of
continuous text in the three font
styles, formatted as if in a large
print book; black ink on white
paper. No italics or all-caps were
used.
 The questionnaire was designed
to request the subjective
legibility rating and preferred
readability of the typefaces.
 Chi-square test of association
and goodness-of-fit tests
(frequency of differences
between typefaces)
 Wilcoxon test (to determine the
Results or Findings
shape or other font-quality factors
do. The authors concluded that
reasonable vs. poor letter spacing,
not fixed-width vs. variable-width
fonts, reduces crowding effects.
 None of the subjects showed any
preference for either of the two
resolutions (Times or Lucida). For
character heights down to .16
degrees and resolutions down to 8
pixel cap-heights, letter shape
quality probably influences
readability more than does
resolution.
 For .16 degree characters, all
subjects showed a slight
preference, ranging from 10-30%
for the typographically spaced font
(Computer Modern Roman).
Exp 1:
 The greatest proportion of subjects
preferred Tiresias. Slightly more
people preferred Arial to Times
New Roman.
 The majority of subjects preferred
to read a large print book in
Tiresias.
 Subjects least preferred typeface
was Times New Roman.
Exp 2:
 The same frequency was found for
both the sans serif and serif
typefaces, but more subjects chose
the semi-serif typeface.
 The mean rating for the typefaces
was lower for the semi-serif
version.
 Legibility rating between the
This is the total over five experiments: 211 (exp 1), 25 (exp 2), 26 (exp 3), 31 (exp 4), and 15 (exp 5).
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
44
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Study
Study Design and
Methods
Fonts Used
degrees of
serifs.
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
N
Subject Characteristics
 Mean age = 56.45 (SD
20.34)
 Female (15), male (5)
 Some could read ordinary
print and others could not.
Exp 3:
 Self-rated vision: poor (23),
fair (3), and good (0).
 Mean age = 63.17 (SD
16.99)
 Female (16), male (10)
 Nearly all subjects could
not read ordinary print.
Exp 4:
 Self-rated vision: poor (11),
fair (12), and good (8).
 Mean age = 68 (SD 21.36)
 Female (19), male (11).
 Of the majority of subjects
who could not read ordinary
print, did read large print,
but some did not.
Exp 5:
 Self-rated measures of
vision: poor (4), fair (7), and
good (4).
 Mean age = 77.27 (SD
8.19)
 Female (12), male (3)
 Eleven out of 15 subjects
could not read ordinary
print and nine of the
subjects read large print
books.
Outcomes Measured, Evaluation
and Statistical Methods
differences in legibility of
typefaces)
Exp 2:
 Questionnaire and sample of
continuous text replicated three
times (Tiresias was altered to
produce sans serif, semi-serif,
and serif). Subjects were
required to respond as to how
legible they found the samples.
 Chi-square (typeface
preference)
 Friedman test (legibility rating)
Exp 3:
 Questionnaire and sample of
continuous text. Tiresias was
altered using Fontographer 4.1
to produce three typefaces with
difference spacing and three
with different weights.
 Two, two-page extracts taken
from a popular author’s large
print book, replicated with
different spacing and weights.
 Subjects were asked to rate the
legibility and preference for what
they would read in a large print
book.
 Friedman test
 Wilcoxon
 Chi-square
Exp 4:
 A questionnaire written in 16pt
Verdana was produced to
inquire about the preferred
shape and size of punctuation
marks. Common punctuation
marks were altered.
 Punctuation marks included:
speech marks, semicolon, colon,
comma, full stop, exclamation
Results or Findings
degree of serif typefaces was not
significant, even for subject that
only had poor or fair vision ratings.
Exp 3:
 Enlarged spacing was preferred by
subjects, then normal spacing, and
then condensed spacing.
 From the weight results, legibility
increased as the weight of the
typeface increased. This was
shown to be statistically significant.
Subjects preferred the typeface
with the darkest weight.
Exp 4:
 Subjects preferred rounded
punctuation shape. In terms of the
size, the “medium” level was the
most legible.
Exp 5:
 All subjects who read large print
books did so by recognizing words
not individual characters.
 Although no significant difference
in preference was found between
degree of serif typefaces, analysis
of reading speeds showed subjects
read samples in a semi-serif
typeface faster than either of the
other samples.
 Subjects preferred normal spacing
to enlarged spacing, as reflected in
reading speeds—which were
significantly faster with a normally
spaced typeface.
 The interaction between the two
main effects “degree of serif” and
“spacing” was not significant.
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Study
Yager D, et al
1998
Study Design and
Methods
To determine if there
is a reading speed
difference between
two fonts, for a fixed
x-height, in two
different luminance
conditions.
Fonts Used
 Dutch (serif)
 Swiss (sans
serif)
 Both are
proportionally
spaced and
matched for xheight
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
N
46
Subject Characteristics
Normal vision (20/20);
optometry and high school
students
Outcomes Measured, Evaluation
and Statistical Methods
mark, question mark,
apostrophe, and brackets.
Exp 5:
 Structured interviews, all
subjects followed the same
procedure to the same worded
questions.
 Five extracts of text were taken
from a popular author’s large
print book.
 One extract was replicated to
produce three typeface samples
with different degrees of serif:
sans serif, semi-serif, and serif.
There were also two spacing
examples (normal and
enlarged). Subjects were asked
which ones they found most
legible.
 Chi-square
 Mixed, two-way analysis of
variance (to analyze subjects’
reading speeds)
 Mauchly’s Test of Sphericity
 Greenhouse-Geisser epsilon
 Reading performance
 Luminance (2 conditions)
 Single letter acuity measured at
low luminance
 Text displayed on a monitor
using RSVP method
 Text was selected from
standardized reading material
with sixth to ninth grade difficulty’
presented in single sentences,
10-13 words in length.
 Subjects read at a distance of
1m. At this distance lower-case
x-height of fonts was 8mm, 27.5
arc-min, measured with ETDRS
chart.
Results or Findings
 At the high luminance, there was
no significant difference between
reading rates (Wilcoxon signed
ranks P = 0.59, n=26).
 By the Wilcoxon signed-ranks test,
there is a significant advantage for
the Swiss font, about 11.5%
greater than for Dutch.
 While the mean advantage was
small, 16 out of 20 of the subjects
read the sans serif font more
rapidly at the low luminance.
 Measurements for single letter
acuity for both fonts at low
luminance (on three subjects with
20/20 corrected vision) showed an
46
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April 2006
Study Attributes
Study
Study Design and
Methods
Fonts Used
N
Subject Characteristics
Outcomes Measured, Evaluation
and Statistical Methods
 The Swiss letters were on
average, 3.3% wider than Dutch.
 One-up, one-down staircase
procedure used.
 VREBR Project Team and CNIB Research
Appendix II—Study Attributes Table
Results or Findings
advantage for the sans-serif,
uniform stroke-width font, Swiss
over Dutch.
 RSVP reading speed is affected in
a low luminance condition for two
proportionally-spaced, x-height
matched fonts. Out of 20 subjects,
16 read the sans-serif font Swiss
more rapidly than the Dutch.
47
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April 2006
Appendix III—Search Strategies
Database Search
The following strategy was used to search the primary group of databases CINAHL, EBM
Reviews, EMBASE, MEDLINE-OVID, and PubMED, as well as the secondary online databases:
AgeLine, Arts and Humanities Index, Canadian Business and Current Affairs (CBCA) Business,
Education, and Reference, Dissertation Abstracts Online, ERIC, IEEE Xplore, MLA International
Bibliography, Public Affairs Information Service (PAIS) International, ProQuest Education,
Psychology, and Research Library, PsychInfo, Sage Full-Text Collections: Communication
Studies, Education, Psychology, Nursing & Health Sciences, SCOPUS, Social Sciences
Abstracts, Web of Science, Web of Knowledge, and WorldCat. Where applicable, subject
headings (MeSH, non-MeSH, and OVID database-specific) and subheadings were used. Each
major subject heading was exploded within the database (this is abbreviated as “exp”). There
were no specific limits set on study design, language, or date.
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
#11
#12
#13
#14
#15
#16
#17
#18
#19
#20
#21
#22
#23
#24
#25
exp VISION DISORDERS
exp VISUALLY IMPAIRED PERSON$ (in EMBASE used ‘exp visual impairment’ and did not
use anything for CINAHL)
exp EYE DISEASES
or/ 1-3
ENLARGED TEXT
FONT
FONT COLOR (or COLOUR)
FONT FAMILY
FONT SIZE
FONT STYLE
HIGH CONTRAST TEXT
LARGE$ CHARACTER$
LARGE PRINT
LEGIBILITY
LETTER SPACING
POINT SIZE
PRINT DISABLED
SERIFS
TEXT COLOR (or COLOUR)
TEXT CONTRAST
TYPE COLOR (or COLOUR)
TYPE SIZE
TYPE SPACING
TYPEFACE
TYPOGRAPHY
(#4 only combined with the keywords when a search had more than 100 results.)
Grey Literature and General Web Search
We searched the following grey literature sources for any research and font legibility standards
and guidelines: GrayLit Network, GreyNet (which has links to multiple, interdisciplinary grey
literature sites). SIGLE (System for Information on Grey Literature) and EAGLE (European
Association for Grey Literature Exploitation) were unavailable online at the time this report was
written. The following keywords were used when performing online searches via Google or
Ask.com: guidelines or standards for text legibility or readability, guidelines or standards for font
or text size, international standards for font or text legibility, large print reading materials, large
print for low vision, type spacing, high contrast text, guidelines or standards for print disabled,
accessible designs for low vision reading, and accessible print materials.
 VREBR Project Team and CNIB Research
48
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April 2006
Appendix IV—Guidelines and Standards
Ranges of Reading Ability†††
Ranges of
Vision
Loss
Visual Acuity
Decimal
Letter
count
Reads
1M at:
1.6
110
160cm
1.25
105
125cm
1.0
100
100cm
0.8
95
80cm
0.63
90
63cm
Statistical Estimates of Reading Ability
Ability
Ranges
Has reserves
Range of
normal
vision
Minimal
impairment
Mild
impairment
Moderate
visual
impairment
Severe
visual
impairment
0.5
85
50cm
0.4
80
40cm
0.32
75
32cm
0.25
70
25cm
0.2
65
20cm
0.16
60
16cm
0.125
55
12.5cm
0.1
50
10cm
0.08
45
8cm
0.063
40
6.3cm
0.05
35
5cm
0.04
30
4cm
0.032
25
3.2cm
0.025
20
2.5cm
0.02
15
2cm
Nearblindness
Less
10
Less
Blindness
0.0
Profound
visual
impairment
Reading Ability
Comments
Normal reading speed
Normal reading distance
Since newsprint is generally
read at around 40cm, this
range has an ample reserve.
(100  10)
Reserve capacity for
small print
Lost reserves
Normal reading speed
Reduced reading
distance
Individuals in this range have
lost their reserve, but have no
or only minimal vision
rehabilitation needs.
(80  10)
No reserve for small
print
(Driver’s license and other
criteria usually fall within this
range)
Normal with aids
Near-normal with
appropriate reading aids
Reading at 25—12.5cm
requires strong reading
glasses (4D-8D) or moderate
power magnifiers.
(60  10)
Low power magnifiers
and large-print books.
(In the U.S. students qualify
for special education
assistance)
Restricted with
aids
Slower than normal with
reading aids
Reading at <10cm precludes
binocular vision. The small
field of strong magnifiers
slows reading.
(40  10)
High power magnifiers
(restricted field)
Vision substitution skills may
be an adjunct to
enhancement aids.
Marginal with
aids
Visual reading is limited.
(20  10)
Uses magnifiers for spot
reading, but may prefer
talking books for leisure.
(Nearimpossible)
No visual reading.
5
0
(0 – 10)
Must relay on talking
books, Braille, or other
non-visual sources).
Use of non-visual skills
increases as rehabilitation
needs shift gradually from
vision enhancement aids to
vision substitution aids.
In this range, individuals must
rely primarily on vision
substitution skills.
Any residual vision becomes
an adjunct to the use of blind
skills.
†††
Colenbrander A. Visual Standards—Aspects and Ranges of Vision Loss. Report prepared for the International council of
Ophthalmology at the 29th International Congress of Ophthalmology. 2002. Sydney, Australia.
 VREBR Project Team and CNIB Research
49
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April 2006
Organizations
The following resources and organizations have basic or expanded guidelines and standards for text
legibility, large print materials, and reading with low vision.
American Council of the Blind
http://www.acb.org/
http://www.acb.org/accessible-formats.html [A guide to making documents accessible to people who are
blind or visually impaired]
American Printing House for the Blind (US)
http://www.aph.org/
Arlene R. Gordon Research Institute (International)
http://www.lighthouse.org/about/research/default.htm
CNIB (Canadian National Institute for the Blind)
http://www.cnib.ca/eng/index.htm
Canadian Library Association
http://www.cla.ca/
Canadian Public Health Association
http://www.cpha.ca/english/index.htm
International Council of Ophthalmology
http://www.icoph.org/index.html
International Federation of Library Associations and Institutions
http://www.ifla.org/
Lighthouse International
http://www.lighthouse.org/default.htm
Luc Devroye (Typograhy Research)
http://cgm.cs.mcgill.ca/~luc/
National Association for the Visually Handicapped (NAVH, US)
http://www.navh.org/
National Information Library Service (Australia)
http://www.nils.org.au/ais/print/resources/lp_guidelines.html
http://www.nils.org.au/ais/print/resources/readability.html
National Information Standards Organization (US)
http://www.niso.org/
National Library for the Blind (UK)
http://www.nlb-online.org/
National Library Service for the Blind (US)
http://www.loc.gov/nls/
Nonprescription Drug Manufacturers Association of Canada
http://www.ndmac.ca/index.cfm
 VREBR Project Team and CNIB Research
Appendix IV—Guidelines and Standards
50
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April 2006
Royal National Institute for the Blind (UK)
http://www.rnib.org.uk/xpedio/groups/public/documents/code/InternetHome.hcsp
http://www.rnib.org.uk/xpedio/groups/public/documents/code/public_rnib003460.hcsp [Good Design link]
http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_seeitright.hcsp [Accessible
Information link]
Royal New Zealand Foundation for the Blind
http://www.rnzfb.org.nz/
Royal Society for the Blind (Australia)
http://www.rsb.org.au/
Society for Environmental Graphic Design
https://www.segd.org/index.html
Tiresias.org (fonts) (UK)
http://www.tiresias.org/
U.S. Food and Drug Administration
http://www.fda.gov/
U.S. Health and Human Services
http://www.hhs.gov/
Vision Australia
http://www.visionaustralia.org.au/
 VREBR Project Team and CNIB Research
Appendix IV—Guidelines and Standards
51