Evaluation and comparison of the effects of different refractive errors, anisometropia and amblyopia on optical cohorence tomography angiography parameters

Optical cohorence tomography angiography (OCTA) is a new non-invasive retina and optic nerve head imaging method that provides three-dimensional imaging as a result of high resolution analysis. In this study, in both myopic, hyperopic, astigmatic subgroups of different refractive status with control eyes (CE) and in both eyes of myopic, hyperopic, astigmatic anisometropic cases with or without amblyopia, it is aimed to evaluate thickness changes which are seen in the macular and retinal nerve fiber layer (RNFL), vascular changes in the macular and optic nerve head, In this study, 484 eyes of 242 cases with different refractive errors, 178 eyes of 89 patients who developed anisometropia and amblyopia due to different refractive errors, and 114 eyes of 57 healthy participants have been evaluated. In the study, myopic, hyperopic, astigmatic cases were divided into 3 subgroups according to the degree of refractive error, and both eyes of patients with or without anisometropia induced amblyopia have beeen examined. Subgroups and CE group have been compared in terms of biometric variables, macular and disc OCTA parameters. Correlations of macular and disc OCTA parameters in refraction groups with with age, spherical equivalent (SE) and axial length (AL) have been evaluated. In the study, it has been seen that as the degree of myopia increases, the area of foveal avascular zone (FAZ) and perimetry (PER) decreases significantly (p <0.05). As the severity of refractive error increases between myopic, hyperopic and astigmatic subgroups, it has been seen that there are significant changes in superficial and deep macular vascular density values and intradisc peripapillary vascular density (p <0.05). When the macular thickness has been examined, it has been observed that the thicknesses of all area decreases significantly except for the foveal area with increasing myopia and that especially the parafoveal area thicknesses decreases significantly with increasing astigmatism and especially perifoveal area thicknesses is observed to increase significantly with increasing hyperopia (p <0.05). As myopia severity increases in especially myopic eyes, it has been found that all RNFL parameters, except for the temporal quadrant, decreases statistically (p <0.05). Of the anisometropic cases, especially the FAZ area of the hypermetropic anisometropic amblyopic eyes has been observed to be significantly wide (p <0.05). It has been observed that superficial and deep macular vascular density decreased significantly in different topographic regions in myopic, hyperopic and astigmatic anisometropic and amblyopic eyes (p <0.05), and that there has been no significant change in optic nerve head perfusion (p> 0.05). It has been observed that macular thickness has been significantly thinner in some areas in myopic anisometropic and amblyopic eyes (p <0.05), and it has been significantly thicker, especially in the perifoveal region in the hyperopic anisometropic and amblyopic eyes (p<0.05). Myopic anisometropic amblyopic cases have been found to be significantly thinner in terms of RNFL thickness parameters, except for the temporal quadrant, compared to the CE group (p <0.05). As the severity of the refractive error increases and as the anisometropia and amblyopia develop, significant structural and microvascular changes have been observed in the macular and optic disc. In the light of these findings, it is concluded that OCTA can be used as an alternative test in the elucidation, treatment and follow-up of the pathogenesis of the mentioned eye diseases. In addition, it will be appropriate to carry out more clinical studies on the case of research.