Ocular Parameters Evaluation in Relation to the Refractive Error using Optical Coherence Topography

Abstract

Introduction:The increasing prevalence of myopia has become a major public health impact due to its potentially blinding ocular complications. This study was done to evaluate the choroidal and retinal thickness, depth of the anterior chamber and the curvature of the cornea using 3D Optical Coherence Topography (OCT) and Optical Coherence Biometry instrument (Zeiss IOLMaster 700) among Saudi female adults with emmetropia, low and moderate myopia. Aim:To evaluate the choroidal thickness, foveal retinal thickness, depth of anterior chamber, Axial Length (AL) and curvature of the cornea between myopic and emmetropic individuals. Materials and Methods:This cross-sectional study was done in the female section of Department of Optometry, College of Applied Medical Science, King Saud University (KSU), Riyadh, in Saudi Arabia. Hundred and four eyes of healthy females between the ages of 19-26 years who fulfilled the inclusion criteria were selected. There was no gender preference; only female subjects were included because this study was done in the female college. The subjects were categorised into emmetropic groups (Spherical Equivalent (SE) ≤ -0.25 D), mild myopic groups (SE between -0.50 to -3.00 D) and moderate myopic groups (SE between -3.00 to -6.00 D). The foveal retinal and subfoveal choroidal thickness was measured using 3D OCT, however AL, Anterior Chamber Depth (ACD) and corneal radius were measured using IOL master. Results:The foveal retinal thickness of moderate myopia (205.55±15.35 μm) was found the same as in emmetropia (204.12±15.44 μm) and mild group (204.64±14.29 μm) with p>0.05. The significant difference was not found in the subfoveal choroidal thickness between these three groups. The mean AL of moderate myopia (25.03±0.75 mm) was significantly higher than mild myopia (23.99±0.74 mm) and emmetropia group (23.15±0.98 mm). There was highly significant difference in the ACD between the emmetropic and myopic groups. However, no significant difference was observed in the mean of corneal radius (K-reading) among the three groups (p>0.05). The corneal radius in total myopic eyes had a weak negative correlation with the AL. Conclusion:This study demonstrated that the foveal retinal and subfoveal choroidal thickness did not differ significantly in emmetropic and myopic groups. Also, positive correlation was noted between the ACD and AL. Pearson’s correlation coefficient (r) in ACD and AL for emmetropic group was found 0.28 and 0.48 for the moderate myopic group.