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Editors Selection IGR 15-4
Epidemiology: Types of glaucoma in indigenous Africans
Comment by Rupert Bourne on:
55212 Prevalence and types of glaucoma among an indigenous African population in southwestern Nigeria, Ashaye A; Ashaolu O; Komolafe O et al., Investigative Ophthalmology and Visual Science, 2013; 54: 7410-7416
Population-based studies that detect glaucoma have confirmed Africa as being the region with the highest prevalence of primary open-angle glaucoma. Meta-analyses of glaucoma prevalence,1-2 draw attention to the scarcity of data in regions such as Africa and the Caribbean. It is therefore of great interest to see Ashaye et al. report for a region of Nigeria a primary open-angle glaucoma (POAG) prevalence of 6.2% in those aged 40 years and older. The authors compare the POAG prevalence with another West-African study in Ghana where for a similar age group, the prevalence was 9.2%.3 The Nigerian study used a cluster sampling technique to randomly select 811 people who were examined close to their homes with an anterior segment slit-lamp examination. Those that failed a statistical cut-off for vertical cup/disc ratio (VCDR) or asymmetry were referred to a base hospital for white-on-white perimetry. The use of the widely adopted ISGEO criteria4 by this group to assign categories of glaucoma diagnosis is very helpful.
The high glaucoma prevalence of which most remains undiagnosed (90%) emphasizes the need forstructured eyecare programs in West Africa that integrate glaucoma detection and treatment
Of the 59 subjects with any form of glaucoma, twothirds (39 subjects, 66%), were given a Category 2 diagnosis which entails a very abnormal optic disc (VCDR ≥ 0.9/ asymmetry ≥ 0.3) and inability to complete perimetry, while a third of the subjects (16, 27.1%) had less abnormal discs (VCDR ≥ 0.7; asymmetry ≥ 0.2; notch) but with a testable glaucomatous visual field defect. These findings emphasize the severity of glaucoma in this population, in whom 6% of those with POAG were bilaterally blind and 10% blind in one eye. The study population was largely ethnically homogenous (Yoruba) and therefore cannot be representative of Nigeria as a whole. However, the high glaucoma prevalence of which most remains undiagnosed (90%) emphasizes the need for structured eyecare programs in West Africa that integrate glaucoma detection and treatment.
References
- Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006;90:262-267.
- Tham YC, Li X, Wong TY, Quigley HA, Aung T, Cheng CY. Global Prevalence of Glaucoma and Projections of Glaucoma Burden through 2040: A Systematic Review and Meta-Analysis. Ophthalmology 2014 Jun 26. pii: S0161-6420(14)00433-3. doi: 10.1016/j.ophtha.2014.05.013. [Epub ahead of print].
- Ntim-Amponsah CT, Amoaku WM, Ofosu-Amaah S, et al. Prevalence of glaucoma in an African population. Eye 2004;18:491-497.
- Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol 2002;86:238-242.