Functional low vision in adults from Latin America: findings from population-based surveys in 15 countries

To review data on functional low vision (FLV) (low vision-visual acuity (VA) < 6/18 (<20/60) to > perception of light (PL+) in the better eye-that is untreatable and uncorrectable) in adults aged 50 years or older from published population-based surveys from 15 countries in Latin America and the Caribbean.

Data from 15 cross-sectional, population-based surveys on blindness and visual impairment (10 national and five subnational) covering 55 643 people > 50 years old in 15 countries from 2003 to 2013 were reanalyzed to extract statistics on FLV. Eleven of the studies used the rapid assessment of avoidable blindness (RAAB) method and four used the rapid assessment of cataract surgical services (RACSS) method. For the 10 national surveys, age-and sex-specific prevalence of FLV was extrapolated against the corresponding population to estimate the total number of people > 50 years old with FLV.

Age- and sex-adjusted prevalence of FLV in people > 50 years old ranged from 0.9% (Guatemala, Mexico, and Uruguay) to 2.2% (Brazil and Cuba) and increased by age. The weighted average prevalence for the 10 national surveys was 1.6%: 1.4% in men and 1.8% in women. For all 10 national studies, a total of 509 164 people > 50 years old were estimated to have FLV. Based on the 910 individuals affected, the main causes of FLV were age-related macular degeneration (weighted average prevalence of 26%), glaucoma (23%), diabetic retinopathy (19%), other posterior segment disease (15%), non-trachomatous corneal opacities (7%), and complications after cataract surgery (4%).

FLV is expected to rise because of 1) the exponential increase of this condition by age, 2) increased life expectancy, and 3) the increase in people > 50 years old. These data can be helpful in planning and developing low vision services for the region; large countries such as Brazil and Mexico would need more studies. Prevention is a major strategy to reduce FLV, as more than 50% of it is preventable.