Risk factors for open-angle glaucoma in Nigeria: results from the Nigeria National Blindness and Visual Impairment Survey.
BACKGROUND
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.


METHODS
A 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.


RESULTS
Thirteen 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.


CONCLUSIONS
Case detection strategies for OAG should be improved for those aged ≥40 years and for ethnic groups most at risk as a public health intervention.
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK. Fatima.Kyari@lshtm.ac.uk.|Department of Ophthalmology, College of Health Sciences (CHS), University of Abuja, Abuja, Nigeria. Fatima.Kyari@lshtm.ac.uk.
Fatima
F
Kyari
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK.|Department of Ophthalmology, Abubakar Tafawa Balewa University Teaching Hospital, Bauchi, Nigeria.
Mohammed M
MM
Abdull
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK.|Moorfields Eye Hospital, London, UK.
Richard
R
Wormald
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK.
Jennifer R
JR
Evans
Moorfields Eye Hospital, London, UK.
Winifred
W
Nolan
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK.|Indian Institute of Public Health, Public Health Foundation of India, Hyderabad, Telangana State, India.
Gudlavelleti V S
GV
Murthy
International Centre for Eye Health (ICEH), Department of Clinical Research, London School of Hygiene & Tropical Medicine (LSHTM), Keppel Street, London, WC1E 7HT, UK.
Clare E
CE
Gilbert
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology; D001794:Blood Pressure / Q000502:physiology; D004522:Educational Status; D005260:Female; D005902:Glaucoma, Open-Angle / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000150:complications; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009549:Nigeria / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D012959:Socioeconomic Factors; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology
Ethnicity; Nigeria; Open-angle glaucoma; Risk factors