Morphometric Study of the Optic Nerve Head Among Northern Nigerian Adults, Using Optical Coherence Tomography

Glaucoma is a common health problem worldwide especially in adult population. It is characterised by progressive irreversible optic nerve head (ONH) damage, due to alterations in retinal ganglion cells nutrition and viability. Early diagnosis is key to better management and prognosis. This study measures the ONH parameters among adults in northern Nigeria, using Optical coherence tomography (OCT). This would provide a reference values of ONH parameters that would help clinicians observe early abnormal optic nerve changes for early diagnosis of glaucoma among the population. Healthy 770 adult volunteers from ethnic northern Nigerians underwent complete ocular examination, including anterior and posterior segment examination. Those with normal findings proceeded to have optic nerve head examination using a Stratus OCT machine. The ONH parameters analysed were; optic disc area (DA), rim area (RA), cup area (CA), and cup-to-disc ratio (CDR). The mean DA, RA, and CDR found in the study were 2.35mm2 SD=+0.88, 1.76mm2 SD=+0.43, and 0.44 SD=+0.21, respectively. The DA and CDR were significantly larger with age (p=0.001) and the RA was found to significantly decline with age. A regression formula was derived to use for the estimation of ONH dimensions based on age. This study provided reference values of the ONH parameters among the northern Nigerians. We also obtained a regression model that could be used to estimate different ONH dimensions from individual’s age, with a reliable accuracy. This would enable an ethnic specific screening protocol for clinicians in screening, diagnosis, and management of optic neuropathies like glaucoma.