Retinal nerve fibre layer thickness and optic nerve head size measured in high myopes by optical coherence tomography

Abstract

Background: The retinal nerve fibre layer (RNFL) thickness is reportedly decreased in myopia; however, magnification adjustment is an important consideration when using optical coherence tomography (OCT) to evaluate myopic eyes. In this study, RNFL thickness and optic nerve head (ONH) size were measured in highly myopic eyes with and without magnification adjustments. The measurements were compared with magnification-adjusted OCT measurements of emmetropic control eyes.

Methods: In this cross-sectional study, RNFL thickness (global circle and quadrants) and ONH size (disc and rim areas) were measured in one eye of each of 70 participants with high myopia. Magnification-adjusted measurements taken in the high myopes were then compared with magnification-adjusted measurements taken in 70 emmetropic controls.

Results: Comparisons of magnification-adjusted measurements between highly myopic and emmetropic control eyes showed that the highly myopic eyes had significantly thicker global and temporal RNFLs (p < 0.05), significantly thinner nasal RNFL (p < 0.05), and significantly larger disc and rim areas (p < 0.05). Superior and inferior RNFL thickness measurements did not differ significantly between the two groups (p > 0.05).

Conclusion: The OCT measurements obtained with magnification adjustment show global and temporal RNFL thicknesses and ONH size increase in highly myopic eyes.

Keywords: high myopia; optic nerve head; retinal nerve fibre layer.