The Vision Loss Expert Group (VLEG) has published new findings about four areas of interest to the blind and low vision community. The report provides timely updates on acuity measurement standards, prevalence of global cases, and prevalence of types of blindness and vision impairment.
For those who are interested in statistics, here are summaries of the report published in the February 2021 edition of The Lancet Global Health:
Definitions of acuity levels of visual impairment
Normal: 6/6 (US: 20/20)
Mild: 6/12 to 6/18 (US: 20/30 to 20/60)
Moderate to severe: 6/18 to 3/60 (US: 20/60 to 20/400)
Blind: Greater than 3/60 (US: 20/400) or less than 10° central field
Estimated mean numbers affected by blindness and vision impairment
Mild: 258 million
Moderate to severe: 295 million
Blind: 43.3 million
Causes of moderate-to-severe vision impairment in people age 50+
Age-related macular degeneration: 196 million (1)
Diabetic retinopathy: 93 million
Inadequate vision correction: 86.1 million
Glaucoma: 79.6 million (2)
Cataract: 78.8 million (3)
Causes of blindness in people age 50+
Cataract: 20 million
Glaucoma: 3.6 million
Inadequate vision correction: 2.3 million
Age-related macular degeneration: 1.8 million
Diabetic retinopathy: 0.86 million
In view of these numbers, the VLEG notes that, over the past three decades, the prevalence of blindness caused by cataract, glaucoma, and age-related macular degeneration has decreased in older adults. At the same time, however, the prevalence of blindness has increased. This suggests that improvements in treatment, pharmacology, and surgical interventions for some eye diseases are yielding success, but that more effort is needed to meet the increasing needs of an aging and growing population.
__________________________________
References to statistics not included in the VLEG report:
1. Global prevalence of age-related macular degeneration and disease burden projection for 2020 and 2040: a systematic review and meta-analysis. Wong WL, et al. Lancet Glob Health. 2014 Feb;2(2):e106-16. doi: 10.1016/S2214-109X(13)70145-1. Epub 2014 Jan 3. PMID: 25104651
3. Global prevalence and major risk factors of diabetic retinopathy. Joanne W Y Yau, et al. PMID: 22301125 PMCID: PMC3322721 DOI: 10.2337/dc11-1909