The Influence of Low to Moderate Myopia on Retinal Nerve Fiber Layer as Assessed by Scanning Laser Polarimetry with Variable Corneal Compensator

Abstract

Purpose: To evaluate the influence of different degrees of myopia on retinal nerve fiber layer (RNFL) as measured by scanning laser polarimetry (SLP) with variable corneal compensator (VCC) in healthy eyes. Methods: One hundred and seventy-four healthy age-matched subjects with low to high myopic and emmetropic eyes underwent RNFL measurement by means of GDxVCC. The GDx parameters included in the analysis were: Temporal-superior-nasal-inferior thickness (TSNIT) average, Superior average, Inferior average, TSNIT standard deviation, Inter-eye symmetry, NFI, Symmetry, Superior ratio, Inferior ratio, Superior/nasal, Maximum modulation, Superior maximum, Inferior maximum, Ellipse modulation, Normalized superior area, Normalized inferior area, Ellipse standard deviation, Ellipse average. The mean value of each SLP parameter of myopic eyes was compared with the mean value of the same parameter of emmetropic eyes. Results: Mean myopia was 3.9 ± 1.5 dpt (range: –2 to –8.25 dpt). TNSIT average was higher in myopic group (p = 0.0111), together with Superior average (p = 0.0244), Symmetry (p < 0.0001) and Ellipse average (p = 0.0111). Two ratio parameters, Superior ratio and Inferior ratio, were higher in emmetropic eyes (p = 0.0179 in both cases). In both the myopic and the emmetropic group, all the SLP assessments of the RNFL fell within the normal range, according to the GDx database. Conclusions: Low to high myopia is not related to clinically relevant variations of SLP parameters, as assessed with GDx-VCC.