Chicago—The patterns of childhood blindness and visual impairment have been changing throughout the world over time. As socioeconomic status improves in many developing countries the major causes are changing, according to Clare Gilbert, MD, MSc, FRCOphth.
As corneal scarring (due to vitamin A deficiency, measles, ophthalmia neonatorum, and use of traditional eye remedies) declines, blindness due to cataract and refractive errors are becoming relatively more important. Blindness due to retinopathy of prematurity (ROP) is emerging as an important cause in middle-income countries and in urban areas in Asia. Dr. Gilbert described the shifts in childhood blindness patterns resulting from the "nurture" components of disease at the American Academy of Ophthalmology annual meeting.
Approximately 1.4 million children are blind worldwide.
Rates of blindness
The rates of childhood blindness vary greatly, influenced by the economic status of a country; the poorer the country, the higher the rates of blindness, Dr. Gilbert pointed out. In affluent countries, for example, the prevalence of childhood blindness is 0.3 per 1,000 children; this is in contrast to very poor countries that have a prevalence of childhood blindness of 1.2 per 1,000.
The causes of blindness also differ in these populations. In affluent populations no cases are attributed to corneal scarring, 10% from cataract and glaucoma, 10% from ROP, and 80% from other causes, such as retinal dystrophies or lesions of the higher visual pathways. In middle-income countries, about 20% of children are visually impaired as the result of cataract or glaucoma, 25% from ROP, and 55% from other causes. In poor countries, 20% are blind from corneal scarring, 20% from cataract or glaucoma, 0% from ROP, and 60% from other causes. In very poor communities, however, up to 50% of cases of blindness result from corneal scarring, 15% from cataract and glaucoma, 0% from ROP, and 35% from other causes, according to Dr. Gilbert.