Alterations in Choroidal Volume and Determinants of Choroidal Volume and Visual Acuity in Entire Macula-involved Myopic Retinoschisis

Background: To evaluate alterations in the choroidal volume (CV) of eyes with entire macula-involved myopic retinoschisis (MRS) and to investigate predictive factors for CV and visual acuity. Methods This cross-sectional observational study recruited 32 MRS eyes, 52 non-MRS highly myopic eyes, and 55 emmetropic eyes. Retinal and choroidal morphological findings were obtained using SD-OCT. The CV of the three groups was compared, and factors associated with CV and BCVA were analyzed. Results The macular CV was significantly lower in MRS eyes than in emmetropic eyes ( P  < 0.0001) and in non-MRS highly myopic eyes ( P  < 0.05). The difference in CV for MRS eyes among the superior (0.34 ± 0.16 mm 3 ), inferior (0.33 ± 0.17 mm 3 ), nasal (0.27 ± 0.12 mm 3 ) and temporal (0.34 ± 0.21 mm 3 ) quadrants was not significant ( P  = 0.3755). Multivariate regression analysis showed that the total macular CV in MRS eyes was negatively correlated with axial length ( P  = 0.0459), decreasing by 0.19 mm 3 for each millimeter of axial length. Refractive error and defects in the ellipsoid zone (EZ) were associated with BCVA in logMAR units ( P  = 0.0075 and 0.0002, respectively); BCVA decreased by 0.027 logMAR units for each diopter of myopia. The total macular retinal volume (RV) in MRS eyes with EZ defects was higher than that in eyes with intact or partially continuous EZs ( P  = 0.0460). Conclusion In MRS eyes, the choroid is thinner, the total macular CV deceases as the axial length increases, and the severity of myopia and the integrity of the EZ, associated with the schisic extent are predictors of visual acuity, and the decrease of the macular CV is not the influencing factor of the visual function.