Nigeria normative data for defining glaucoma in prevalence surveys

Area of Science:

• Ophthalmology
• Public Health
• Epidemiology

Background:

• Glaucoma diagnosis relies on normative data, which is lacking for specific populations like Nigerian adults.
• Cross-sectional surveys are vital for understanding disease prevalence in diverse communities.

Purpose of the Study:

• To establish normative values for defining glaucoma in Nigerian adults.
• To provide data for accurate glaucoma prevalence estimation in sub-Saharan Africa.

Main Methods:

• A nationally representative sample of 15,027 Nigerians aged ≥ 40 years was selected using multistage stratified cluster random sampling.
• A normative subset of 1759 participants underwent detailed eye examinations, including visual field testing (FDT), intraocular pressure (IOP) measurement, and optic disc grading.
• International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria were used to determine normative values for vertical cup/disc ratio (VCDR) and IOP.

Main Results:

• The 97.5th percentile VCDR was 0.7 for structural and functional glaucoma evidence (Category 1).
• The 99.5th percentile VCDR was 0.75 for advanced structural damage with unproven visual field loss (Category 2).
• The 99.5th percentile IOP criterion was 28 mmHg for cases where optic disc and visual field data were unavailable (Category 3).

Conclusions:

• The established normative values are applicable for glaucoma prevalence studies in Nigeria and similar African regions.
• These findings contribute to a better understanding of glaucoma epidemiology in underrepresented populations.
• Further research may differentiate between open-angle and angle-closure glaucoma mechanisms.