The effect of low and moderate myopia on corneal, retinal, and intraretinal layers’ thickness by spectral optical coherence tomography

Abstract Introduction: An important goal of biomedical physics and engineering is to study possible confounding factors in diagnosis or treatment to minimize erogenous interpretations due to overestimation or covering pathology-related changes. We aimed to examine the effect of refractive error on corneal thickness, retinal thickness (including its layers), and optic disc parameters in low myopia and moderate myopia, as compared to the emmetropic group. Material and methods: Sixty eyes from 30 (18 women) young, healthy, physically active, non-smokers, with normal color perception, and no ophthalmological or neurological medical history Caucasians at the age of 24.6 ± 1.5 years were examined. The studied groups were defined based on the SE (spherical equivalent): emmetropia (−0.5 D ≤ SE ≤ 0.75 D, 20 eyes), low myopia (−3 D < SE < -0.5 D, 20 eyes), and moderate myopia (−6 ≤ SE ≤ −3 D, 20 eyes). Spectral optical coherence tomography imaging (SOCT) through SOCT Copernicus HR device (OPTOPOL Technology Sp. z o.o., Poland) was used. Results: Corneal thickness, peripapillary RNFL thickness, and optic disc parameters didn’t change between emmetropic, low myopia, and moderate myopia groups. However, macular retinal thickness decreased with increasing refractive error. Interestingly, particular retinal layers’ thicknesses changed differently with increasing spherical equivalent (SE). A thickening of external macular retina layers was observed in the central and inner sectors, while a thinning of internal retinal layers was seen mainly in the outer ring when SE increased from emmetropia to moderate myopia. Conclusions: Our findings suggest that changes in retinal thickness due to refractive error may appear even in earlier stages than high myopia. Moreover, different retina layers change differently with SE and not every sector behaves in the same manner. These results are especially worth noting, as they point out the necessity of taking into account different behaviors of retinal layers in low and moderately myopic eyes in interpreting the measurement results when diagnosing ocular pathologies or preparing ophthalmologic surgeries.