Draft (Sep 2013)
ITE Section, Education Bureau
Eye Care Resource Package for Parents
Section
Content
1
Common eye problems related to use of digital
devices
2
Bad habits may lead to eye problems related to use
of digital devices
3
What eye problems can occur after prolonged use of
digital devices?
4
Management and Prevention of Computer Vision
Syndrome
Appendix 1
Content summary table
Appendix 2
Common eye refractive errors
Appendix 3
Suggested activities – vision testing
Appendix 4
Other suggested activities
1
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
Eye Care Resource Package for Parents
1. Common Eye Problems Related to Use of Digital Devices
1.1. The use of digital screen devices to view small type for prolonged
periods, frequently at close working distances, has become commonplace
in modern society. Many individuals use multiple devices such as a
desktop and laptop computers as well as one or more hand-held devices.
These present a variety of visual demands that are significantly different
from those of printed materials in terms of working distances, viewing
angles and text sizes.
2. Bad habits may lead to eye problems related to use of digital devices
2.1. There are several bad habits that may lead to the development of eye
problems related to the use of digital screen devices. You should look out
for the following 5 signs to identify those children at risk:
 Using digital devices for prolonged periods (>1 hour) without rest
 Rubbing eyes while using digital devices
 Frowning and squinting while using digital devices
 Holding digital devices too close (<20 inches or 50-51cm) to eyes
 Lack of blinking
3. What eye problems can occur after prolonged use of digital devices?
3.1. Staring at your computer screen, smartphone, or other digital devices for
long periods may cause a number of eye problems. Computer vision
syndrome is a term to describe these eye problems, and may affect up to
90% of computer users, whose symptoms may include asthenopia
(eyestrain), headaches, dry eye, diplopia (double vision) and blurred
vision after prolonged use (>2 hours) of computer or other digital screen
devices.
4. Management and Prevention of Computer Vision Syndrome
4.1. To prevent eye problems related to prolonged use of digital screen
devices, there are generally three adjustments to be remembered – the
Triple-A (Adjustment) preventive strategies:
4.1.1
Adjust environment
a. Use large monitor or screen magnifier to reduce eye
strain
b. Ensure chair is close to computer and sitting
comfortably to reduce stress on eyes trying to find the
best viewing angle
c. Change monitor settings to a reflective lighting scheme
d. Keep bright lighting overhead to a minimum
2
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
e. Keep window light off to side; use blinds or an anti-glare
screen
f. Position the screen of digital devices to reduce
reflection from windows or overhead lights
4.1.2
Adjust digital screen devices
a. Position screen to look at it slightly downward (about 5
inches or 12-13cm) at an optimal distance (about 25
inches or 63.5cm away)
b. Place reference materials as close to the screen as
possible (e.g., using a document holder beside monitor)
to lessen the need to constantly refocus the eyes
c. Optimise personal screen brightness and contrast that
your eyes feel most comfortable with
4.1.3
Adjust behaviours
a. Remember to blink regularly and completely
b. “20-20-20 see beyond the screen rule” – look at
something 20 feet (or 6 m) away for 20 seconds every
20 minutes
c. Limit electronic device use and increase outdoor play
d. Seek advice from eye doctors to exclude serious eye
problems if symptoms persist
3
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
Appendix 1 - Summary
1. Common eye problems related to
use of digital devices
The use of digital screen devices to
view small type for prolonged periods,
frequently at close working distances,
has become commonplace in modern
society. Many individuals use multiple
devices such as a desktop and laptop
computers as well as one or more
hand-held devices. These present a
variety of visual demands that are
significantly different from those of
printed materials in terms of working
distances, viewing angles and text
sizes.
2. Bad habits may lead to eye
problems related to use of digital
devices
There are several bad habits that may
lead to the development of eye
problems related to the use of digital
screen devices. You should look out for
the following 5 signs to identify those
children at risk:
 Using digital devices for
prolonged periods (>1 hour)
without rest
 Rubbing eyes while using
digital devices
 Frowning and squinting
while using digital devices
 Holding digital devices too
close (<20 inches or <5051cm) to eyes
 Lack of blinking
3. What eye problems can occur after
prolonged use of digital devices?
Staring at your computer screen,
smartphone, or other digital devices
for long periods may cause a number of
eye problems. Computer vision
syndrome is a term to describe these
eye problems, and may affect up to
90% of computer users, whose
symptoms may include asthenopia
(eyestrain), headaches, dry eye,
diplopia (double vision) and blurred
vision after prolonged use (>2 hours)
of computer or other digital screen
devices.
4
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
4. Management and Prevention of
Computer Vision Syndrome
To prevent eye problems related to
prolonged use of digital screen devices,
there are generally three adjustments
to be remembered – the Triple-A
(Adjustment) preventive strategies:
(images to be developed)
4.1.1 Adjust environment
a. Use large monitor or screen
magnifier to reduce eye strain
b. Ensure chair is close to computer
and sitting comfortably to reduce
stress on eyes trying to find the
best viewing angle
c. Change monitor settings to a
reflective lighting scheme
d. Keep bright lighting overhead to a
minimum
e. Keep window light off to side; use
blinds or an anti-glare screen
f. Position the screen of digital
devices to reduce reflection from
windows or overhead lights
4.1.2 Adjust digital screen devices
a. Position screen to look at it slightly
downward (about 5 inches or 1213cm) at an optimal distance
(about 25 inches or 63.5cm away)
b. Place reference materials as close
to the screen as possible (e.g.,
using a document holder beside
monitor) to lessen the need to
constantly refocus the eyes
c. Optimise personal screen
brightness and contrast that your
eyes feel most comfortable with
4.1.3 Adjust behaviours
a. Remember to blink regularly and
completely
b. “20-20-20 see beyond the screen
rule” – look at something 20 feet (or
6m) away for 20 seconds every 20
minutes
c. Limit electronic device use and
increase outdoor play
d. Seek advice from eye doctors to
exclude serious eye problems if
symptoms persist
5
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
Appendix 2 - Common eye refractive errors
One page introduction of common eye refreactive errors (by using cartoon
illustration).
Normal eye sight
Myopia (nearsightedness)
Hyperopia (farsightedness)
Astigmatism
Strabismus
6
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
Appendix 3 - Suggested activities
(1) Eyesight examination
Objective: It is a preliminary eyesight examination for children.
Instruction: Place the testing chart (come with an A3 paper containing the
Snellen Chart) 20 feet behind the children. Children with normal eyesight
should be able to see the characters on last row.
(2) Binocular Single Vision test (images to be developed)
Objective: Our eye receives images from surrounding environment and
the images are transmitted to our brain for interpretation. A Binocular
Single vision is then formed. Since both eyes are receiving images
simultaneously, it is also called Simultaneous Perception. As a result of
this, we have the feeling of Depth Perception and Stereopsis.
The 3 tests are testing your ability to receive the images in terms of
simultaneous perception, depth perception and stereopsis.
(a) Simultaneous perception
Instruction: Place the diagram 40 to 50cm apart from eye and put a
pencil in between the eye and the diagram. You should focus on the
pencil tip. Please tell if you could see the third image in the middle.
(b) Depth perception
Instruction: Place the diagram 40 to 50cm apart from eye and put a
pencil in between the eye and the diagram. You should focus on the
pencil tip. Please tell if you could see the third 3-Dimensional image
with feeling of ‘depth’.
(c) Stereopsis
Instruction: Place the diagram 40 to 50cm apart from eye and put a
pencil in between the eye and the diagram. You should focus on the
pencil tip. Please tell if you could see the third circle chain image with
feeling of ‘depth’ (that is the heart icon appear in the middle while “I”
and “U” may appear on top or down below the heart icon.
(3) Pinhole Vision Testing (images to be developed)
Objective: If a person has ‘refractive errors” in his eyes, he should be able
to see a clear image through a small pinhole (diameter: about 1mm) as
there is only one single light ray entering the eye. Regardless the length of
7
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Draft (Sep 2013)
ITE Section, Education Bureau
eyeball and the shape of the cornea, the clearness of the image would not
be affected.
Instruction: This is to test if the child has ‘refractive errors” in his eyes. A
card paper with a small pinhole (diameter: about 1mm) can help.
First, parents should place a calendar apart from themselves in about 10
feet and they can see the words on the calendar clearly. Parents can allow
their children to see the words using both eyes first and with separated
eye later. If the children cannot see the words on the calendar clearly
using both eyes due to refractive errors, they should try to see the words
through the pinhole card paper. They should obtain a clearer image
subsequently. If the children cannot see the words through the pinhole
card paper, he/she may have other eye problems. Parents should seek eye
doctors help for further examination.
(4) Optical illusion (images to be developed)
Objective: Our brain sometimes will mislead us in the interpretation of
images due to some assumptions in our brain. These assumptions in our
brain will let us have optical illusion. The below 5 tests are to give you the
feeling of optical illusion.
Instruction: Please look at the below 5 diagrams and answer the
questions.
(1) Which line is longer? Line A or B?
(2) Which line is a straight line? aa’ or ab’?
(3) Are the lines all vertical?
(4) Are the lines all horizontal?
(5) How many black dot(s) and white dot(s) are there?
Appendix 4 - Other suggested activities
(1)
You may ask your children to observe the behaviour of the family
members at home for a day and record down the good and bad behaviours that
may affect their risk of developing eye problems related to the use of digital
devices.
(2)
You may ask your children to design a poster to promote eye health
related to the use of digital devices.
-End-
8
Eye Care Resource Package for Parents
Developed by: Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong