Effect of Refractive Status on Peripapillary Retinal Nerve Fiber Layer Thickness and Vascular Density: A Prospective Optical Coherence Tomography Angiography-Based Study.

Abstract

Background: There have been different reports of the retinal nerve fiber layer (RNFL) thickness in myopic and hyperopic patients in optical coherence tomography (OCT)-based studies. This study was conducted to evaluate the correlation between vascular density of the optic nerve head and refractive errors in healthy subjects using OCT-angiography (OCTA).

Methods: In a prospective interventional case series, 47 healthy subjects were enrolled consequently. The target spherical equivalent was -1.00 to +1.00, -1.00 to -6.00, and +1.00 to +4.00 in the emmetropia group (A), myopia group (B), and hyperopia group (C), respectively. The astigmatism was less than 3.00 diopters in all patients. The thickness of the retinal nerve fiber layer (RNFL), the vascular density of the optic nerve head (ONH), and the peripapillary area were measured. Statistical independent samples t-tests were used to evaluate between-group differences and the hyperopia group (group C) was considered as the reference group.

Results: Eighty-eight eyes from 47 patients were included. Twenty-five eyes (28.4%) were emmetrope, 27 eyes (30.7%) were myopic, and 36 eyes (40.9%) were hyperopic. The mean rim area was significantly lower in myopic eyes than in hyperopic eyes (1.64 vs. 1.80, P=0.039). Although the lowest mean of RNFL thickness was observed in myopic eyes, the difference between groups was not statistically significant. The nasal radial peripapillary capillaries (RPC) were significantly lower in myopic eyes versus hyperopic (49.04 vs.52.72, P=0.006). There was not any significant difference between the mean of RPC capillary inside the disc.

Conclusion: The vascular density in the RPC area was significantly lower in myopic eyes than in hyperopic and emmetropic eyes.