Global data on visual impairment in the year 2002

Resnikoff S, Pascolini D, Etya’ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti SP.

This paper presents estimates of the prevalence of visual impairment and its causes in 2002, based on the best available evidence derived from recent studies. Estimates were determined from data on low vision and blindness as defined in the International statistical classifi- cation of diseases, injuries and causes of death, 10th revision. The number of people with visual impairment worldwide in 2002 was in excess of 161 million, of whom about 37 million were blind.

The burden of visual impairment is not distributed uniformly throughout the world: the least developed regions carry the largest share. Visual impairment is also unequally distributed across age groups, being largely confined to adults 50 years of age and older. A distribution imbalance is also found with regard to gender throughout the world: females have a significantly higher risk of having visual impairment than males.

Notwithstanding the progress in surgical intervention that has been made in many countries over the last few decades, cataract remains the leading cause of visual impairment in all regions of the world, except in the most developed countries. Other major causes of visual impairment are, in order of importance, glaucoma, age-related macular degeneration, diabetic retinopathy and trachoma.

Reprinted courtesy of: Bulletin of the World Health Organization 2004;82; 844-51.

Commentary

Improving trend in global blindness

A global estimate of the magnitude and causes of visual impairment based on the 1990 world population data gave 38 million blind. This estimate was later extrapolated to the 1996 world population to give 45 million blind, and subsequently projected to the 2020 world population estimating 76 million blind. This increasing trend provided the basis for the 1999 launch of VISION 2020, the Global Initiative for the Elimination of Avoidable Blindness. New analysis using 2002 data reports that 37 million were blind. However, refractive error was not included, which implies that the actual global magnitude is greater. It is likely that this positive trend is due to two major factors:

More data from population-based studies on visual impairment carried out over the last decade are available allowing for more accurate estimates to be made.
There have been significant achievements in the prevention and management of avoidable blindness. These include:

Increased public awareness and utilisation of eye health care services
Increased availability and affordability of eye health care services
As part of primary health care, control activities against trachoma, onchocerciasis, vitamin A deficiency and other eye infections have resulted in a significant decrease in the numbers of blind compared to earlier estimates
Impressive achievements in blindness control in some countries, for example India, The Gambia, Morocco and Thailand
Increased global political commitment to prevention of visual impairment
Increased professional commitment to prevention of visual impairment
Commitment and support of nongovernmental organisations
Involvement and partnership with the corporate sector.

VISION 2020, the Global Initiative for the Elimination of Avoidable Blindness, needs not only to be sustained but strengthened further if the goals are to be achieved. The positive trend over the last 10 years as shown by the new estimates should not be a cause for complacency as demonstrated by the statistic that in 2002, 18 million people are blind in both eyes because they cannot afford or access cataract surgery.