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Editors Selection IGR 25-3

Epidemiology: Glaucoma prevalence in Africa: how far have we come?

Comment by Rupert Bourne on:

127176 Prevalence of glaucoma in Africa: A systematic review and Bayesian meta-analysis, Asiamah R; Asiamah R; Kyei S; Owusu G et al., PLoS ONE, 2025; 20: e0330567

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This paper by Asiamah and co-authors reports the prevalence of glaucoma and its subtypes in Africa based on data extracted from just 9 population-based studies, published between 2000 and 2019. The natural inclination on reading this paper is to compare the data sources and approach taken by the 2006 report on global prevalence of glaucoma by Quigley and Broman,1 which was updated by Tham and Quigley in 2014.2 In the 2006 report, there were only 4 studies from Africa supplemented by African-American participants of the Baltimore Eye Survey and the Barbados Eye Study, and the paucity of data meant that a Europe estimate had to be used for ACG in Africa. The 2014 report involved 5 African studies, two from Ghana, two from South Africa and one from Tanzania, and again the authors could not reliably perform an age- and gender-stratified analysis of PACG and glaucoma (defined as POAG and PACG combined) in non-Asian regions due to small numbers of PACG cases. Returning to this paper by Asiamah et al, their literature search identified 4 additional studies, 3 from Nigeria (West Africa) and one from Kenya. This exemplifies the scarcity of population-based datasets on the prevalence of glaucoma in Africa in the last 2 decades, and still no sources from North and Central Africa. Clearly, access to raw data for age-and gender-specific prevalence rates of subtypes of glaucoma allows for much more precise estimates in a meta-analysis but it is unclear from this paper whether this was available. The fact that the authors could not report on sex differences in prevalence for 3 of the nine studies suggests that access to age- and sex-disaggregated data was suboptimal. A meta-regression comparing glaucoma prevalence between geographical regions showed no significant difference, nor was there a temporal change in glaucoma prevalence, which was unlikely to be meaningful given the paucity of studies in this period. The authors report prevalence of glaucoma (unclassified glaucoma) to be 5.59% (95% Credible Interval, 4.32% to 7.74%) although they do not specify in which age range this applies. Presuming this is for adults aged 40+ years (consistent with the age range of most of the included studies), this value is within the confidence intervals of 4.79% (2.63-8.03) reported by Tham and Quigley in 2014.2 Although knowledge of the prevalence of glaucoma and its subtypes (irrespective of impact on vision) is limited by the number of studies whose design permits this, there are many more population-based studies whose design permits estimates of those vision impaired or blinded by glaucoma, with the SubSaharan Africa region having the highest age-standardized prevalence of glaucoma-related blindness and vision impairment worldwide.3 More population-based studies that measure prevalence of glaucoma per se in African countries remains important if we are to understand the baseline and future impact of an ageing population on eyecare services in Africa.

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