Blindness or low vision affects 3.3 million Americans age40 and over, or one in 28, according to authors of a new study in the April issue of Archives of Ophthalmology (122:477-485).
But with the ageing of the population, this figure is projected to reach 5.5 million by the year 2020.
The study, sponsored by the National Eye Institute(NEI), part of US government's National Institutesof Health, provides the most robust and up-to-date estimates available of the burden of visual impairment.
It also follows publication this month of a study showing that vision loss caused by age-related macular degeneration (AMD) could be partly reversed by taking the antioxidant lutein. Other supplements, such as antioxidant vitamins and zinc could also help the millions at risk for advanced age-related macular degeneration avoid vision loss in coming years, suggests research.
The study identifies AMD as the leading cause of blindness among white Americans, accounting for 54 per cent of all blindness. Among AfricanAmericans, the leading causes of blindness are cataract and glaucoma while glaucoma is the most common cause of blindness in Hispanics.
The study reports that low vision and blindness increase significantly with age, particularly in people over age 65. People 80 years of age and older currently make up 8 per cent of the population, but account for 69 per cent of blindness.
In addition, one in every 12 people with diabetes age 40 and olderhas vision-threatening diabetic retinopathy. Diabetes is also increasing dramatically in the US.
NEI director Paul A. Sieving said the data will direct future research efforts. "Developing blindness preventionstrategies could help address the potentially devastatingimpact of the increased prevalence of eye diseases in thenext few decades," he said.
Frederick Ferris, director of clinical researchat the NEI, said that the estimates of low vision andblindness "are the first to take full advantage ofinformation derived from several excellent eye diseasestudies reported since 1990. This data, collected fromdifferent populations, allow us to identify the most commoneye diseases and give us good estimates of their relativemagnitudes".
The study was conducted by the Eye Disease PrevalenceResearch Group, a consortium of principal investigators whoanalysed standardized data from several highquality studies and then derived prevalence rates modelled to the US population using 2000 census data. Projections were based on 2020 US census estimates.