Purpose:
In spite of the growing interest in optical coherence tomography (OCT), optic nerve head (ONH) morphology in different ethnic and gender groups has been poorly investigated. We investigated ONH morphology and peripapillary retinal nerve fiber layer (RNFL) thickness in healthy subjects using optical coherence tomography (OCT) across different ethnicities comparing Asian (i.e. Indian sub-continent) and Caucasian individuals, gender and age.
Methods:
High-resolution spectral domain OCT (Copernicus, 3 µm) was used to image the ONH in 123 healthy participants. Disc margins and position of internal limiting membrane and RNFL were defined manually to minimize inaccuracies.
Results:
Asian participants had significantly larger cup areas (p=0.005) mainly due to elongated horizontal diameters (p=0.003). Disc areas were larger in Caucasian males compared to females but smaller in Asians males compared to females (interaction: p=0.002). There were no significant differences in rim areas or RNFL thicknesses between Asians and Caucasians or males and females. Both rim areas (p=0.007) and mean RNFL thicknesses (p=0.02) significantly decreased with age resulting in larger cup volumes and cup/disc area ratio.
Conclusions:
Using high resolution OCT, we have described for the first time significant differences in normal ONH morphology and peripapillary RNFL thickness between Asian and Caucasian ethnicities. We also show a differential effect of gender in these two ethnicities. These factors must be taken into consideration when pathology of the optic nerve or RNFL is suspected.
Keywords: optic nerve • anatomy