Vision Screening in the Elderly: Current Literature and Recommendations
Yingming Amy Chen, Class of 2011, Faculty of Medicine, University of Toronto
Dr. Mary Thomas, Department of Family Medicine, University of Toronto
Abstract: Vision impairment is one of the leading causes of morbidity in the elderly population.
Major causes of vision loss include presbyopia, cataract, age-related macular degeneration,
glaucoma, and diabetic retinopathy. A vision screening program has the potential to identify
millions of adults at risk for vision loss and vision-related co-morbidities. Previous guidelines in
the 1990s recommended routine visual acuity screening by primary care physicians. However,
subsequent published data have demonstrated a lack of effectiveness in quality-of-life
outcomes with current screening strategies, likely due to the low sensitivity of the screening
tests. Until further studies establish the accuracy of any vision test in predicting visual function,
routine vision screening in the elderly in the primary care setting is not warranted. The
introduction of other vision tests into the screening protocol, including low contrast visual
acuity (VA) assessment, stereoptic testing, and visual field testing, warrants further
investigation and cost-benefit evaluation.
Introduction
Vision impairment (VI) occurs in more than 13% of the elderly population and is one of
the leading causes of morbidity in adults over the age of 651. The prevalence of VI increases
with age, from 1% in 65-69 year olds, to 17% in the over-80 population2. Out of the 60,000
people registered as legally blind in Canada, over 50% are accounted for by adults older than
603, 4. Leading causes of VI in the elderly include presbyopia, cataract, age-related macular
degeneration (ARMD), glaucoma, and diabetic retinopathy, together contributing to over 13
million cases of eye disorders in the US2, 5, 6. Most visual problems in the elderly occur gradually
and often go unnoticed by patients and their health care providers. Subtle changes in reading,
TV watching, and facial recognition go unreported in the early stages1, especially in those with
cognitive impairment7. Studies have consistently shown that adults with low vision are at higher
risk of depression, falls, and self-administered medication errors8-13. Complicated by decreased
motor ability and reaction time, VI leads to significant psychosocial, comorbid, and functional
deficits in the elderly. An effective vision screening program, therefore, has the potential to
offer significant quality of life (QOL) benefits to our aging population. This article reviews the
major causes of VI in the elderly, followed by a discussion of current evidence for and against
vision screening.
Major Causes of Visual Impairment
Presbyopia is manifested by reduced near vision with no change in distance visual acuity
(VA). Universal with aging, it is caused by hardening of the lens, resulting in decreased capacity
of near accommodation. Presbyopia affects 6.7 million adults over the age of 65 in the US6.
Detection of presbyopia is possible in the primary care office using the near vision Snellen eye
chart, although multiple studies suggest that the method is unreliable when compared to a
complete ophthalmological exam14-16. Presbyopia is readily correctable with eyeglasses or
contact lenses, with one study demonstrating that 60% of presbyopic patients can attain VA
better than 20/40 with correction17.
Cataract is the most common cause of vision loss in North America and accounts for
15% of cases of blindness in Canada 1. It is caused by opacification in the lens as a result of
aging, trauma, systemic disease, radiation, and/or medication18. Patients with cataracts present
with reduced VA, blurred vision, difficulty driving at night, and the perception of glare and
“halo” around objects18. The incidence of age-related cataract is about 50% in people between
65 and 74-year-olds and over 70% in those over 752. The definitive treatment of cataract is
surgical removal of the opaque lens, with subsequent implantation of an intraocular lens
(IOL)18. Treatment recovers vision to 20/40 or better in nearly 90% of patients19, and improves
their writing and fine motor control, as well as their capacity to carry out activities of daily
living20, 21. However, the effect of surgery on the risk of falls and fractures remains uncertain22.
Posterior capsule opacfication occurs in about 28% of post-surgical cases at 5 years23, but can
be successfully treated with laser capsulotomy24. Cataracts can be detected with a handheld
ophthalmoscope as part of office screening1; however, there is no literature to date on the
sensitivity and specificity of the technique compared to slit lamp examination.
ARMD is the leading cause of irreversible blindness among Caucasians older than 65,
currently affecting 1.75 million in the US5. Patients often complain of distorted near vision or
blurred vision as first symptoms, followed by the loss of central vision18. Vision is lost due to the
accumulation of metabolic waste products in the retinal pigment epithelium (RPE), leading to
atrophy of the RPE and the overlying photoreceptor cells18. Fundoscopy demonstrates pigment
stippling in the central retina as well as the appearance of drusen, which are yellow hyaline
deposits in Bruch’s membrane18. “Dry”, or atrophic ARMD, accounts for 90% of the disorder,
with most patients maintaining VA above 20/801. “Wet”, or exudative ARMD, on the other
hand, occurs because of abnormal choriocapillaris vessel growth, leading to disruptions of the
macular structure and profound vision loss1. Diagnosis of ARMD is achieved by fundoscopy in
the ophthalmologist’s office. The Amsler grid, a 10x10cm grid, is often used to detect linear
distortions, metamorphopsia, and central scotoma in patients with early ARMD3. However, its
effectiveness in the primary care setting has not been validated. Treatment for ARMD is aimed
to slow disease progression and prevent further vision loss. To that end, the Age-Related Eye
Disease Study (ARES) reported that the combination of multivitamins and zinc reduces the rate
of VA loss in “dry” ARMD compared with placebo25. Laser photocoagulation destroys new
vessels in “wet” ARMD and has been shown to preserve VA in a pooled Cochrane analysis of 5
trials26. Furthermore, photodynamic therapy with verteporfin has demonstrated superior
efficacy in preventing VA loss compared with placebo27, although no QOL outcomes were
studied. More recently, intravitreal injection of anti-VEGF antibodies such as Pegaptanib
(Macugen)28 and ranibizumab (Lucentis)29 have shown promise in treating neovascular ARMD.
Glaucoma and diabetic retinopathy are the fourth and fifth leading causes of VI in the
elderly. Detection and diagnosis are usually not achieved in the primary care office. Patients
with risk factors for either should be referred to ophthalmology for diagnosis and follow-up.
The Effectiveness of Vision Screening
In 1996, the United States Preventative Services Task Force (USPSTF) recommended
routine screening in primary care with a Snellen eye chart30. Although data on the association
between VA screening and QOL improvement was scarce at the time, the recommendations
were made based on the belief that vision screening meets most of the criteria of an acceptable
screening test (see Table 1, screening criteria adapted from Wilson et al., 197131). However,
studies since conducted have consistently shown screening’s lack of effectiveness in improving
visual function and vision-related QOL.
What is the evidence?
The 2008 Cochrane review on community vision screening in the elderly evaluated
visual outcome data of 5 trials conducted between 1984 and 200332. An additional 3 studies
were cited in a review by Chou et al., who assessed the evidence for the updated USPSTF
recommendations7. Table 2 summarizes results from the studies33-40; a ninth study41 published
in 2009 is also included. Interventions included screening questions, Snellen or Glasgow eye
chart, and a complete eye exam, and were compared to no screening or delayed screening in
study controls. Follow-up times ranged from 6 months to 3.9 years. Outcome was assessed
using self-reported or measured changes in VA, the Visual Function Questionnaire-25 score (a
self-rated questionnaire), and/or the rate of falls and fractures. All 9 studies showed that
despite the identification of patients with reported or measured VI, vision screening did not
result in improved VA or vision-related QOL outcomes overall. The study with the largest
sample size, cited in both aforementioned reviews, found universal vision screening identified
about 10 times more patients with VI than no screening, but found no difference in the rate of
VA worse than 20/60 after 3- to 5-year follow-up37. In Cumming et al.’s study comparing
subjects who had complete eye exams to those who did not, increased incidence of falls (RR
1.57, Cl 1.2-2.05) and fractures (RR 1.74, Cl 0.97-3.11) occurred in the intervention group at 12
months33.
Following the emergence of these data, the updated USPSTF guidelines in 2009
concluded that “current evidence is insufficient to assess the balance of benefits and harms of
screening for VA for the improvement of outcomes in older adults.” 42
Why does screening lack effectiveness?
Reasons behind the lack of benefit in the vision screening trials have yet to be
elucidated; but several hypotheses on the dissociation between screening and QOL outcomes
have been put forward.
First, screening methods used in the trials may not have identified the right group of
patients for referral – that is, the screening tests may be insensitive. All trials thus far have used
either screening questions or VA tests to detect VI. Studies evaluating the accuracy of screening
questions have found questions or questionnaires have low accuracy compared to VA 34 or a
detailed ophthalmological exam15, 34, 43. Data from Hiller et al.’s study showed that self-perceived
vision deficit has a sensitivity of as low as 20-30%44. Furthermore, the Snellen eye chart testing
on its own is not sensitive at diagnosing clinical visual disorders such as ARMD or glaucoma,
both of which are not necessarily associated with impaired VA14-16, 45. Refractive errors can be
diagnosed with VA testing in combination with the pinhole46, but the use of the pinhole
apparatus is prone to errors47, 48. In addition, one has to consider that VI in the elderly is not
solely caused by reduced VA. Brabyn et al. found that high contrast VA is relatively retained in
the aging eye compared to other domains of visual function, such as low contrast VA, visual
field, color discrimination, stereopsis, and depth perception49. Real objects (e.g. stairs) most
often have low contrast; therefore, deficits may not be readily detected by the high contrast
office Snellen eye chart. One study evaluating the value of Amsler grids in detecting ARMD
found a sensitivity of only 19% when compared to a complete eye exam14. No studies have yet
evaluated the accuracy of direct fundoscopy in the primary office setting.
Second, failure of patients to access effective interventions after referral could also
explain the lack of effectiveness in the outcome. Patients may suffer from cognitive or mobility
impairment and could not reach the referral appointments, or they simply did not perceive the
need for intervention7, 48.
Third, outcome assessment used in the studies may have been inadequate. Follow-up
interviews or questionnaires are subjective measures and have uncertain accuracy. VI is
underreported in the elderly population; patients adapt daily living to vision deficits and may
not notice mild deterioration or improvement from year to year. The increased incidence of
falls and fractures in Cumming et al.’s study could be caused by the need for an adjustment
period in frail older adults after receiving new eyeglasses33. Alternatively, increased activities
after treatment may place an elderly person at higher risk for accidental falls33.
Conclusions
Despite the high prevalence of VI in the elderly population and the availability of
beneficial treatments, current strategies of vision screening have not improved visual function
and/or QOL outcomes at a statistically significant level. As of the present, routine vision
screening using screening questions and/or Snellen VA tests are neither sensitive nor costeffective. Current health promotion in vision care should continue to target those who notice a
change in vision, those at high risk of visual disorders (e.g. diabetes, family history of glaucoma
or ARMD), and those with high risk of falls or previous fractures42.
The number of good quality studies on vision screening remains low. Key questions on
the effectiveness of the screening protocol cannot be answered with a high degree of
confidence without certainty in the accuracy and reliability of the screening tools and outcome
measures. Presently, we need better quality research on the diagnostic accuracy of various
screening techniques compared to the gold standard. A battery of tests may provide a more
complete assessment of visual function and be better related to the consequences of visionrelated QOL outcomes7. Future studies should evaluate the feasibility of introducing more
complex visual testing tools into primary care. Should new testing tools prove more reliable, we
need to further consider the cost of time administering the test, the cost of treating
asymptomatic vision disorders, and the cost of screening complications.
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