Abstract
BackgroundThe glaucoma-specific blindness prevalence in Nigeria (0.7 %, 95 % CI 0.6–0.9 %) among those aged ≥40 years is one of the highest ever reported. This study determined the risk factors for open-angle glaucoma (OAG) in adults examined in the Nigeria National Blindness and Visual Impairment Survey.MethodsA nationally representative sample of 13,591 people aged ≥40 years in 305 clusters in Nigeria were examined (response rate 90.4 %) between January 2005 to June 2007. Everyone had logMAR visual acuity measurement, Frequency Doubling Technology (FDT) visual field testing, autorefraction, A-scan biometry and optic disc assessment. Full ocular examination (n = 6397), included Goldmann applanation tonometry. Values for defining glaucoma using International Society of Geographical and Epidemiological Ophthalmology criteria were derived from the study population. Disc images were graded by Moorfields Eye Hospital Reading Centre. Socio-demographic factors (age, gender, ethnicity, literacy and place of residence), ocular parameters (intraocular pressure [IOP], axial length and mean ocular perfusion pressure [MOPP]) and systemic parameters (blood pressure, blood glucose and body mass index [BMI]) were assessed for association with OAG.ResultsThirteen thousand eighty-one (96 %) of 13,591 participants had vertical cup:disc ratio measured in at least one eye. 682 eyes of 462 participants were classified as OAG, with 12,738 controls. In univariate analyses the following were associated with OAG: increasing age, male gender, Igbo and Yoruba ethnic groups, illiteracy, longer axial length, higher IOP, lower MOPP, greater severity of hypertension and low BMI (underweight). In multivariate analysis, increasing age (odds ratio [OR] 1.04, 95 % CI 1.03–1.05), higher IOP (OR 1.22, 95 % CI 1.18–1.25) and Igbo ethnicity (OR 1.73, 95 % CI 1.18–2.56) were independent risk factors for OAG.ConclusionCase detection strategies for OAG should be improved for those aged ≥40 years and for ethnic groups most at risk as a public health intervention.
Highlights
The glaucoma-specific blindness prevalence in Nigeria (0.7 %, 95 % confidence intervals (CI) 0.6–0.9 %) among those aged ≥40 years is one of the highest ever reported
We examined the association between open-angle glaucoma (OAG) and each risk factor separately and report odds ratios with 95 % confidence intervals (CI)
In the Nigeria Blindness Survey, 950/ 27,182 (3.50 %) eyes of 682/13,591 (5.02 %) participants had glaucoma according to the International Society for Geographical and Epidemiological Ophthalmology (ISGEO) criteria, of which 320 eyes of 208 persons were classified as OAG by gonioscopy. 375 eyes had Van Herick’s anterior chamber (AC) angle estimation but did not undergo gonioscopy
Summary
The glaucoma-specific blindness prevalence in Nigeria (0.7 %, 95 % CI 0.6–0.9 %) among those aged ≥40 years is one of the highest ever reported. This study determined the risk factors for open-angle glaucoma (OAG) in adults examined in the Nigeria National Blindness and Visual Impairment Survey. Studies of risk factors for OAG in sub-Saharan Africa and Africanderived black populations have reported that increasing age [3,4,5,6, 11,12,13] and higher intra-ocular pressures (IOP) [3, 4, 12, 14] are consistent and important risk factors. The prevalence of glaucoma was higher in those with darker skin and of African birth [13], which suggest possible influence of environmental factors and inter-ethnic variation in the prevalence and risk of OAG within black populations, mediated by genetic factors. Very few studies have explored other socio-demographic and systemic risk factors
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