Causes of visual impairment in central Ethiopia.

A survey conducted on a stable, mainly rural population of 60,820 in Central Ethiopia revealed an overall blindness prevalence of 1.1%. A follow up study was carried out to accurately determine the etiologies and causes of visual loss and impairment. A detailed ophthalmic evaluation was done on 523 out of 872 individuals identified as being visually impaired. The results showed that 194 (37%) were blind (Categories 3, 4, and 5 = maximum visual acuity less than 3/60 in the better eye). One hundred and seven (21%) (Categories 1 & 2 = maximum visual acuity better than 3/60 to less than 6/18 in the better eye using the WHO categories of visual impairment). The rest 222 (43%) were blind in one eye only. The commonest anatomical cause of blindness is corneal (32%). Cataract (25%), atrophied globe(s) (20%) and glaucoma (17%) follow as the other leading causes. Trachoma (35%), degenerative conditions (35%) and other infections (9%) were the major etiologies of blindness. Similar pattern of anatomical causation was observed in those classified under categories of visual impairment 1 and 2, referred to as "low vision". The most important etiologies of low vision were trachoma (30%), degenerative (24%), trauma (13%) and other infections (8%). Trauma was the most important etiology of monocular blindness (39%). Blindness was either preventable or curable in 74% of the cases.