The prevalence and incidence of visual impairment in people of age 20-59 years in industrialized countries: a review.
BACKGROUND
Reviews on the prevalence of blindness and low vision in persons of age 20 to 59 years are lacking. We have therefore carried out a review based on a Medline search.


METHODS
The review was confined to epidemiological studies performed in Western Europe, North America and Australia covering the age group 20 to 59 years where there were comparable definitions of blindness and low vision according to the IAPB and WHO classification of blindness and low vision.


RESULTS
Three surveys, four register studies and two studies based on multiple sources matched our selection criteria. Blindness and low vision are described separately. Blindness: Only one study, based on multiple sources, covered the whole age group 20 to 59 years. In this study the overall prevalence of blindness was 0.08%. The prevalence of blindness was 0.04% among those 20-39 years old, whereas in the age group 40-59 years it was 0.1% in two surveys and one study on multiple sources. However, the prevalence was higher, 0.5% among whites and 0.7% among colored, in The Baltimore Eye Study. The definition of blindness was similar in all three studies. Low vision: Three studies provided data on the prevalence of low vision in the age group 20-59 years, although the number of cases was very small. In one study the prevalence of a visual acuity < or = 6/24 to 6/48 was 0.07% and in another the prevalence was 0.17% using < 6/18 to 0.5/60. No person with low vision was found in the third study.


CONCLUSIONS
The existing epidemiological data on blindness and low vision among adults aged 20 to 59 years are insufficient. Epidemiological studies based on multiple sources are needed for the study of rare conditions such as blindness and low vision.
Rothe Nissen
Kamilla
K
National Eye Clinic for the Visually Impaired, Hellerup, Denmark. rothe.nissen@dadlnet.dk
Sjølie
Anne Katrin
AK
Jensen
Hanne
H
Borch-Johnsen
Knut
K
Rosenberg
Thomas
T
D000328:Adult; D001315:Australia / Q000453:epidemiology; D001766:Blindness / Q000453:epidemiology*; D016208:Databases, Factual; D019049:Developed Countries / Q000706:statistics & numerical data*; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D015995:Prevalence; D015354:Vision, Low / Q000453:epidemiology*; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*