Structured Abstract
Please note: In 2003, the CTF updated its Grades of
Recommendations to include an "I Recommendation" for situations where
insufficient evidence exists to allow a recommendation to be made.
(Formerly, these situations were captured under a "C
Recommendation".) This change is not retroactive, and all
"C Recommendations" made prior to 2003 have not been
reevaluated in light of the new "I" recommendation grade. For a
discussion of these recommendation grades, please link to the 2003 article in
the Canadian Medical Association Journal here.
Screening for Visual Impairment in the Elderly
Prepared by Christopher Patterson, MD, FRCPC,
Professor and Head, Division of Geriatric Medicine, McMaster University,
Hamilton, Ontario
These recommendations were finalized by the Task Force in January 1994
Contents
Objective
To make recommendations about screening for visual impairment caused by
presbyopia, cataract, age-related macular degeneration (ARMD), glaucoma
and diabetic retinopathy in elderly persons in Canada.
Burden
of Suffering
Thirteen percent of those over age 65 have some form of visual impairment.
Almost 8% have severe impairment (blindness in both eyes or inability to
read newsprint even with glasses). About 1% of those aged over 40 years
have bilateral blindness. Legal blindness (less than 20/200) occurs in
up to 3% aged 60, and nearly 11% at age 80. In 1989, there were 63,576
registered blind people in Canada. The leading causes of visual impairment
in older individuals are presbyopia, cataracts, age-related macular degeneration
(ARMD), glaucoma and diabetic retinopathy. In presbyopia the crystalline
lens becomes thicker and less flexible, leading to visual impairment, but
not usually blindness. Cataracts, defined as any opacity within the lens,
accounts for 15% of blindness in Canada. ARMD is a leading cause of blindness
in most Western countries, accounting for about 50% of new cases of blindness
in Canada. Risk factors include hyperopia, positive family history, smoking,
blue eyes and chemical exposure at work. Glaucoma is a clinical syndrome
consisting of a triad of intraocular hypertension (usually greater than
or equal to 20 mmHg, a characteristic peripheral visual field loss, and
atrophy of the optic nerve head. Risk factors for progression include:
age, level of intraocular pressure, diabetes, myopia, black race, and vascular
problems including systemic hypertension. Diabetic retinopathy (DR) occurs
in both type I and type II diabetes. The estimated 5 year incidence of
retinopathy in diabetics rises from 2.7% at age 55 to 5.4% at age 75.
Options
Screening options were the Snellen sight card, fundoscopy (ophthalmoscopy),
tonometry (Schiotz tonometer), and perimetry (Humphrey automated perimeter
device).
Outcomes
Sensitivity, specificity and positive predictive value of screening tests;
vision (visual acuity), and visual fields.
Evidence
MEDLINE was searched from 1986 to December 1993 using the search terms
"glaucoma" or "glaucoma suspect", "mass screening" or "vision screening",
"clinical trial" (publication type), "glaucoma - drug therapy", "intraocular
pressure - drug effect", "ocular hypertension - drug therapy", "timolol
- administration and dosage", "vision disorders", "aged", "diabetic retinopathy",
"age-related macular degeneration", "cataracts", and "retinal diseases".
Recommendations were graded as:
|
A
|
Good evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
B
|
Fair evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
C
|
Poor evidence regarding inclusion or exclusion of the condition
in a PHE, but recommendations may be made on other grounds. |
|
D
|
Fair evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
|
E
|
Good evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
Quality of evidence was rated according to 5 levels:
|
I
|
Evidence from at least 1 properly randomized controlled
trial (RCT). |
|
II-1
|
Evidence from well-designed controlled trials without randomization. |
|
II-2
|
Evidence from well-designed cohort or case-control analytic
studies, preferably from more than 1 centre or research group. |
|
II-3
|
Evidence from comparisons between times or places with
or without the intervention. Dramatic results in uncontrolled experiments
could also be included here. |
|
III
|
Opinions of respected authorities, based on clinical experience,
descriptive studies or reports of expert committees. |
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits,
Harms, and Costs
In a community survey, the Snellen sight card (visual acuity box) had a
sensitivity of 94% and a specificity of 89% compared with ophthalmological
assessment. Viewing through a pinhole (to minimize refractive error) resulted
in a sensitivity of 79% and a specificity of 98%. Glasses or contact lenses
can correct refractive errors. Surgical removal of cataracts is highly
effective in restoring vision if good retinal functioning and adequate
refraction exist. Lens removal combined with intraocular lens implantation
improves vision in about 90% of patients. Serious complications occur in
£
1% of patients.
Detection of proliferative diabetic retinopathy or macular edema with
fundoscopy depends on technique and experience. Sensitivity of ophthalmoscopy
without pupillary dilation is 38% to 50% when performed by diabetologists
or experienced technicians, but 0% when performed by nurses. 3 RCTs confirm
that Xenon Arc or Argon laser photocoagulation treatment of retinopathy
maintains vision and reduces visual loss.
ARMD can be detected with fundoscopy by a trained technician. In 3 RCTs
of Argon laser photocoagulation for ARMD, vision of treated persons was
preserved compared with non-treated persons.
Sensitivity and specificity of fundoscopy (performed by an experienced
ophthalmoscopist) for detecting glaucoma (increased optic cup to disc ratio
of >60%) can exceed 90%. Lower accuracy would be expected when performed
by family physicians. The Schiotz tonometer has a sensitivity of 50%, and
a positive predictive value of 5%. The Humphrey automated perimeter device
has a sensitivity of 90% and a specificity of 91% compared with Goldman
Perimetry. RCTs have found that intraocular pressure reduction (topical
application of beta-adrenergic blocking drugs or pilocarpine) can reduce
the development of new visual field defects, but findings are inconsistent.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.
-
There is fair evidence to include screening with the Snellen sight card
in the PHE of people 65 years of age and older [B,
II-2].
-
There is fair evidence to include (in the PHE of persons with diabetes)
screening for diabetic retinopathy, using fundoscopy or retinal photography,
in the PHE of persons aged 65+ with diabetes [B,
I, III].
-
There is insufficient evidence to include or exclude (in the PHE) screening
for ARMD using fundoscopy in the PHE of people aged 65+ [C,
I, III].
-
There is insufficient evidence to include or exclude (in the PHE) screening
for glaucoma using fundoscopy, tonometry or automated perimetry [C,
I,
II-2, III].
Validation
This report was externally peer-reviewed. The American Academy of Ophthalmology
recommends annual ophthalmoscopy and tonometry for persons >40 years, complete
examination by an ophthalmologist at least once between 35 and 45 years,
and every 5 years after 50. The American Optometric Association recommends
a complete eye/vision exam including tonometry for persons >35 years. The
1989 U.S. Preventive Services Task Force suggested advising persons at
high risk for glaucoma to be tested by an eye specialist, but not with
Schiotz. Screening of elderly persons was recommended. The American College
of Physicians, American Diabetes Association and American Academy of Ophthalmology
recommend regular screening of persons with diabetes using stereoscopic
fundus photography or annual dilated ophthalmoscopic exam.
Sponsors
The Canadian Task Force on Preventive Health Care
eveloped this guideline with funding from Health Canada.
Selected
References
Source Document
Link to Full Text of this
review
Link to Summary Table of Recommendations of this review
Link to Selected References list of this review
Link to 1995 update: Screening for visual
problems among elderly patients
Top of Page
CTFPHC
Home Page
Copyright © 1997 Canadian
Task Force on Preventive Health Care
For any technical issues please contact: webmaster@ctfphc.org
Last modified: June 10, 1998.