ObjectiveTo observe the changes of subfoveal choroidal thickness (SFCT) under the macular center recess after trabeculectomy in eyes with open-angle glaucoma (POAG), and to preliminarily analyze its relationship with visual function. MethodsA retrospective case-control study. 117 patients with POAG who were diagnosed by ophthalmologic examination and treated with trabeculectomy in Department of Ophthalmology of Shangluo Hospital of Traditional Chinese Medicine from January 2021 to December 2023 were included in the study. Among them, 63 cases were male; 54 cases were female. All of them underwent naked-eye visual acuity, best-corrected visual acuity (BCVA), refraction, optical coherence tomography (OCT) examination, and axial length measurement. SFCT was measured using enhanced deep imaging with an OCT instrument. Based on the visual function reduction at 1 month after surgery, the patients were categorized into a visual function unreduced group and a visual function reduced group of 67 and 50 cases, respectively. Visual function included binocular adjustment amplitude and sensitivity; visual quality included objective scattering index (OSI) and modulation transfer function (MTF). Changes in SFCT and visual function-related indexes were analyzed by repeated-measures analysis of variance; the risk associated with changes in SFCT and visual function-related indexes was evaluated by a binary logistic regression model; and the relationship between SFCT and post-surgical visual function loss was analyzed by a Joint model; the SFCT and post-surgical visual function reduction was analyzed by a Joint model; the dose-response relationship between SFCT and post-surgical visual function decompensation was analyzed by applying the restricted cubic spline (RCS). Decision curve (DCA) was used to predict visual hypoplasia. ResultsComparison of the percentage of patients with different ages, anterior chamber hemorrhage, and post-surgical anterior chamber inflammatory response in the unreduced visual function group and the reduced visual function group showed statistically significant differences (P＜0.05). The results of the main effect test showed that the differences between SFCT and visual function adjustment amplitude, sensitivity time effect, between-group effect, and interaction effect were statistically significant in both groups (P＜0.05). The results of the separate effects test showed that compared with the preoperative period, the SFCT, accommodation amplitude, and sensitivity of the affected eyes of the two groups were significantly increased at different times after surgery, and the differences were statistically significant (P＜0.05). The results of multivariate ANOVA showed that SFCT, accommodation amplitude, and sensitivity at different times before and after surgery were significantly lower in the group with reduced visual function than in the group without reduced visual function, and the differences were statistically significant (P＜0.05). The △naked-eye visual acuity, △BCVA, △OSI, and △MTF of the patients in the group with reduced visual function were significantly lower than those in the group without reduced visual function, and the differences were all statistically significant (P＜0.05). Correlation analysis showed that SFCT was positively correlated with △adjustment amplitude, △sensitivity, △naked-eye visual acuity, △BCVA, △OSI, and △MTF (r=0.426, 0.419, 0.311, 0.315, 0.325, 0.285; P＜0.05). Multiple linear regression analysis showed that △SFCT was positively correlated with △adjustment amplitude, △sensitivity, △naked-eye visual acuity, △BCVA, △OSI, and △MTF before and after adjusting for confounders (P＜0.05). The results of Joint modeling analysis showed that the risk of visual function decompensation was increased by 5% for every 1 µm increase in SFCT. The results of RCS analysis showed a nonlinear correlation between SFCT and surgical The RCS analysis showed that there was a nonlinear relationship between SFCT and post-surgical visual impairment for nonlinear test (P＜0.001); the threshold effect analysis showed that the fold point at which SFCT affected post-surgical visual impairment was 243.25 µm.The DCA analysis showed that SFCT predicted a significant increase in the net clinical benefit rate of post-surgical visual impairment for risk thresholds ranging from 0.00 to 0.84. ConclusionsAfter POAG trabeculectomy, SFCT of those with or without reduced visual function are significantly thickened compared to pre-surgery; the magnitude of visual function adjustment and sensitivity tended to increase significantly after surgery. Naked eye visual acuity, BCVA, OSI, and MTF all have a significant effect on postoperative visual function.