Rapid assessment of avoidable blindness in the northern eThekwini district of KwaZulu-Natal Province, South Africa

Abstract

Aim: To determine the prevalence and causes of visual impairment, cataract surgical coverage and barriers to cataract surgery amongst people in the northern eThekwini district of KwaZuluNatal Province, South Africa.

Method: Thirty-three clusters of 50 subjects ≥ 50 years old were randomly selected. Consenting subjects underwent enumeration to establish a demographic profile and thereafter a clinical examination. Visual acuity (VA) was measured with a Tumbling ‘E’ chart; participants having a VA < 6/18 were retested with a pinhole. If no improvement in VA occurred, subjects underwent clinical examination, including a dilated fundus exam where necessary, to determine the cause of visual impairment.

Results: Of the 1650 subjects selected, 1542 (93.5%) were examined. The overall prevalence of blindness was 1.9%. The age- and gender-adjusted prevalence of blindness was 2.1%, severe visual impairment (SVI) 1.2%, and moderate visual impairment (MVI) 3.9%. Untreated cataract was the major cause of blindness (55.2%) and SVI (53.3%), and uncorrected refractive error was the major cause of MVI (49.1%). The cataract surgical coverage rate was 70% at visual acuity < 3/60 level; 51% at visual acuity < 6/60 level; and 38% at visual acuity < 6/18 level. Poor awareness of cataract surgical intervention was the main reason that participants with untreated cataracts had not used existing cataract services.

Conclusion: The prevalence of blindness in the study region was lower (by 1.98%) than World Health Organization estimates of 9% for the Africa-E sub-region (within which South Africa falls). There is no permanent cataract service in this region; the lower cataract surgical coverage rates indicate that a permanent eye care centre could significantly alleviate avoidable blindness, particularly that caused by cataract.