Quantitative Assessment of the Choroidal Vessel Diameter during the Recovery of Form-Deprivation Myopia in Guinea Pigs

Purpose The development and recovery (REC) of myopia is associated with changing of choroidal thickness (CT) in the model of guinea pigs. Nitric oxide synthase (NOS) is an enzyme which can affect choroidal vasodilatation. This study wants to investigate the changes of choroidal vessel diameter (CVD) and NOS during the REC of form-deprivation (FD) myopia in guinea pigs. Methods Forty-eight guinea pigs were randomly assigned to the normal control (NC) group, FD group (FD for 21 d), and four REC groups: REC1/2 group (removal the deprivation and re-exposure to the normal environment for 1/2 d), REC1 group (1 d), REC 2 group (2 d), and REC7 group (7 d). CT was measured by optical coherence tomography (OCT), and CVD of foveal choroid was quantitatively assessed on OCT angiography images using MATLAB software at each time point. NOS in choroid was measured using enzyme-linked immunosorbent assays. Measurements were compared between groups and correlations between CT, CVD, and NOS were assessed using regression analyses. Results CVD and CT in FD group were significantly smaller than in NC group (both p < .05), while the NOS significantly larger (p < .001). When deprivation was removed, CVD and NOS were significantly larger and reached a peak in the REC1 group, while CT reached the peak in the REC2 group, then all gradually decreased, and no significant differences were observed in NC and REC7 group (all p > .05). In the REC and NC groups, there was a significant positive correlation between CVD and NOS (p < .001), CVD and CT (p = .0092), but no correlation was found between NOS and CT (p > .05). Conclusions This study indicated that the CVD in guinea pigs could be significantly dilated following myopia REC, and this change coincides with changes in NOS and CT.