Comparison of Retinal Nerve Fiber Layer Profile in Subjects with Myopia and Emmetropia Using Scanning Laser Polarimetry

Purpose: To compare retinal nerve fiber layer (RNFL) profile in subjects with myopia and emmetropia using GDx variable corneal compensator (VCC) Methods: Besides ophthalmologic standard examination (refraction, visual acuity and slit-lamp examination, applanation tonometry, and funduscopy), perimetry and scanning laser polarimetry (SLP) were performed. 171 healthy age-matched subjects with low to high myopia (90 subjects) and emmetropia (81 subjects) underwent RNFL analysis by means of GDx VCC. The mean value of each parameter was compared in myopic and emmetropic eyes. Results: Mean myopia was 3.43±1.19 diopter (D) (range, -0.50 to -6.50). Except for ratio parameters, RNFL parameters were significantly lower in myopic patients. TSNIT standard deviation (p=0.026), nerve fiber indicator (NFI) (p=0.027), superior/nasal (p<0.0001), max modulation (p=0.003), ellipse modulation (p=0.0244) and Symmetry (p=0.028) were higher in myopic group. In both groups, all of RNFL measurements were within the normal range. There was a gradual decrease in RNFL thickness associated with aging in myopic patients (simple regression analysis, p<0.05). There was also a gradual decrease in temporal-superior-nasal-inferior thickness (TSNIT) average and superior maximum with increasing degree of myopia (simple regression analysis, p<0.05). Conclusion: RNFL thicknesses gradually decreased with increasing age in myopic patients. Patients with myopia had significantly lower RNFL thickness than normal subjects and, although weakened by wide age range of myopic group, there was a linear negative correlation between severity of myopia and RNFL thickness in myopic patients.