Findings from a Rapid Assessment of Avoidable Blindness (RAAB) in Southern Malawi

Abstract

BackgroundData on prevalence and causes of avoidable blindness in Malawi are not readily available. The purpose of this study was to determine the prevalence and causes of blindness in persons aged 50 and above in southern Malawi to plan eye care services for the community.MethodologyA population-based survey was conducted in 7 districts in southern Malawi. Villages were selected by probability proportionate to size within each district. Clusters were further subdivided into segments. A predetermined number of segments were selected randomly in each cluster. The survey team moved from house to house in each segment until they had examined 50 people over the age of 50. Examination consisted of visual acuity measurement with tumbling “E” chart and ocular examination by an ophthalmologist. Participants were categorized by visual acuity. Those who were visually impaired (VA<6/18 in the better eye with available correction) were assigned a main cause of visual loss. Further information was sought from anyone who had received cataract surgery.ResultsA total number of 3,583 persons aged 50 and above were sampled; among these 3,430 (95.7%) were examined. The prevalence of blindness (presenting visual acuity <3/60 in the better eye) among persons aged 50 and above was 3.3% (95% CI 2.5–4.1). Cataract was the most common cause of blindness contributing to 48.2% of all cases, followed by glaucoma (15.8%) and cornea scarring (12.3%). The cataract surgical coverage in blind persons was 44.6%.ConclusionThe prevalence of blindness and visual impairment in persons aged 50 and above was lower than the WHO estimate for Malawi. The majority of the causes were avoidable, with cataract accounting for approximately half of all cases of blindness. The data suggests that expansion of eye care programs to address avoidable causes of blindness is necessary in this area of southern Malawi.

Outcomes of manual small-incision cataract surgery using standard 22 dioptre intraocular lenses at Nkhoma Eye Hospital, Malawi

“…The proportion of good outcomes (and corresponding low percentage of poor outcomes) in clinic-based studies is higher than in population-based surveys in sub-Saharan Africa [14][15][16][17]. However, findings from clinic-based studies such as ours may not be representative of the wider population.…”

“…However, findings from clinic-based studies such as ours may not be representative of the wider population. A recent rapid assessment survey of avoidable blindness in southern Malawi revealed that 52.6 % of operated eyes had a good outcome (could see 6/18) with pinhole-correction, and, encouragingly, the majority of cataract operations (91.0 %) used IOLs [17]. Although there was a high proportion (32.1 %) that could not see 6/60 with best correction, most subjects were very or partially satisfied with the visual outcome (84.8 % of all persons who had surgery) with only 3 % very unsatisfied.…”

Blindness and visual impairment due to age-related cataract in sub-Saharan Africa: a systematic review of recent population-based studies

“…The only other country contributing two separate published studies was Tanzania, including RAAB surveys from Kilimanjaro and Zanzibar 20 21. Additional RAAB surveys were performed in Botswana,9 Burundi,22 Malawi,17 Rwanda,19 Eritrea12 and Kenya 16. Five studies were national surveys 9 12–14 18.…”

The Need for a Revised Approach to Epidemiological Monitoring of the Prevalence of Visual Impairment

“…5,6,[8][9][10]14,15 In contrast, Powe and colleagues found that 89.7% of all eyes with cataract operated in the United States mostly during the 1980s-when conventional extracapsular surgery predominated-achieved visual acuity of 20/40 or better. 16 While developing country cases with advanced cataracts and possibly neglected co-morbidities likely are fundamentally more difficult and less likely to lead to good outcomes than US cases were in the 1980s, and the method of ascertaining visual outcome is non-identical, there appears to be a large quality gap.…”

“…At the most straightforward level, the results show us that blindness remains a major problem in Eritrea, and that diseases such as cataract and glaucoma which require ophthalmic care are an important cause of blindness, as in several other surveys from Africa and elsewhere in the world. [5][6][7][8][9][10][11][12][13][14][15] While more than half of severe visual loss or blindness was attributed to cataract, only about 1% was attributed to surgical complications. However, in reading further (as noted by the authors), we find that blindness due to complications of cataract surgery must be one of the leading causes of blindness in single eyes, because 182 eyes (39.2% of those operated) present with visual acuity worse than 6/60.…”