Macular Choroidal Thickness and Choriocapillaris Vessel Density Alterations in Type 2 Diabetics with High Myopia

Introduction: The purpose of this study was to investigate the change of macular choroidal thickness and choriocapillaris vessel density in type 2 diabetic with high myopia. Methods: This cross-sectional study recruited a total of 182 patients (182 eyes) in the Affiliated Hospital of Chengde Medical University between January 2018 and December 2021, including myopia+diabetes patients (40 eyes), T2D patients without myopia patients (47 eyes), myopia patients (45 eyes) and healthy volunteers (50 eyes). The choroidal thickness and choriocapillaris vessel density of macular were measured in all subjects by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). Results: The choroidal thickness in myopic, diabetes, myopia+diabetes groups were statistically significantly lower than that in control group (p < 0.001). Further pairwise comparisons showed that the choroidal thicknesses in myopia+diabetes group were statistically significantly lower than that in diabetes group (p < 0.001). The choriocapillaris vessel density in diabetes, myopia+diabetes groups were statistically significantly lower than that in control group (p < 0.001). Interestingly, there were no significant difference in choriocapillaris vessel density between myopia group and control group (p > 0.05). Further pairwise comparisons showed that the choriocapillaris thicknesses in myopia+diabetes group were statistically significantly lower than that in myopia group (p < 0.001), while no statistically significant differences were found between diabetes group and myopia+diabetes group (p > 0.05). Conclusion: The choroidal thickness of the patients with high myopia and diabetes (without DR?was significantly lower than that of normal people and diabetic patients, but the choriocapillaris vessel density was not significantly different from that of normal people, which may be one of the protective mechanisms of high myopia against DR.