Impact of Major Retinal Vessel Position on Sectoral Peripapillary Retinal Nerve Fiber Layer Thickness in Healthy Eyes

The position of the major retinal vessels varies across healthy individuals. This measurement significantly correlates with sectoral retinal nerve fiber layer thickness and can potentially improve the use of normative databases.

Evaluate the variability of major vessel position (MVP) among healthy individuals and its effect on optical coherence tomography (OCT) sectoral retinal nerve fiber layer (RNFL) thickness measurements.

Circumpapillary RNFL (cpRNFL) circle scans were collected from 88 healthy individuals (88 eyes). The MVP was determined using the commercial Heidelberg Eye Explorer software. For each of the 4 main temporal vessels, the MVP was defined as the angular distance (degrees) on the 3.5 mm diameter circumpapillary B-scan between the point where the circle scan intersects the vessel and the point where the circle intersects with the disc-to-fovea line.

There was considerable variability in MVP among the healthy individuals. The positions of the superior and inferior veins were distributed normally, whereas the distributions of the arteries were skewed temporally. Sectoral cpRNFL thickness significantly correlated with superior and inferior MVP. As the MVP angle increased, the cpRNFL thickness in the superior-nasal and inferior-nasal sectors increased (Spearman correlations coefficient between 0.2 and 0.42, P <0.05). In contrast, cpRNFL thickness of the superior-temporal and inferior-temporal sectors decreased (correlation between -0.41 and -0.26, P <0.05). The thickness of the temporal sector also decreased as MVP increased (correlation between -0.43 and -0.22, P <0.05). No significant correlation was found between MVP and nasal sector thickness.

The MVP is a reliable proxy for the distribution of the major RNFL bundles. Adjusting cpRNFL measurements based on MVP might improve the reliability of normative databases and reduce artifacts, particularly false positives, related to RNFL bundle position.