A Study of Retinal Nerve Fiber Layer Thickness and Other Optic Nerve Head Parameters in Cases of Amblyopia

Introduction: Amblyopia is a disorder of decreased visual acuity and contrast sensitivity, studies in past have shown retinal changes in amblyopic eyes, which was refuted by other studies. Studies in the recent past have reported variable results on retinal nerve fiber layer (RNFL) thickness in amblyopic eyes. Therefore, there is still a gap in present knowledge. This study was conducted to study RNFL thickness and other optic nerve head (ONH) parameters in amblyopic and better fellow eyes. Materials and Methods: A total of 30 diagnosed cases of amblyopia (four cases of meridional, 11 cases of anisometropic, three cases of strabismic, eight cases of ammetropic, and four cases of form deprivation amblyopia) were divided into two groups: Group A (amblyopic eyes - 30 eyes) and Group B (better fellow eyes - 30 eyes). All the eyes underwent visual acuity assessment, refraction (under cycloplegia), anterior segment evaluation, and fundus evaluation. All the patients underwent ONH evaluation by Cirrus 500 spectral-domain high-definition optical coherence tomography, before and after occlusion therapy. The ONH parameters studied were average RNFL thickness, rim area, disc area, and cup volume. The data were analyzed using SPSS version 25:00. Results: The RNFL thickness was less in amblyopic eyes as compared to normal fellow eyes, (P = 0.002). There was a positive correlation between RNFL thickness and rim area in both the groups, but it was significant (P = 0.02) in Group A only. No statistically significant difference was found between the rim area, disc area, and cup volume between the two groups. Conclusion: The RNFL thickness was found to be significantly less in amblyopic eyes, also there was a significant positive correlation between RNFL thickness and rim area in Group A (P = 0.02).