Effects of anti-VEGF therapy on choroidal thickness in eyes with diabetic macular edema

Diabetic macular edema (DME) is a leading cause of visual impairment in working-age adults. Although anti-vascular endothelial growth factor (VEGF) therapy is the standard treatment for DME, its effects on choroidal structure remain incompletely characterized. This study aimed to evaluate changes in subfoveal choroidal thickness (SFCT) following intravitreal Conbercept injection in eyes with center-involved DME.

In this prospective study, 40 patients (51 eyes) with center-involved DME were enrolled between August 2019 and November 2022. Based on diabetic retinopathy severity, eyes were classified into non-proliferative DR with macular edema (NPDR-ME, n = 36) and proliferative DR with macular edema (PDR-ME, n = 15) groups. All eyes received intravitreal Conbercept (0.5 mg) injections. Best-corrected visual acuity (BCVA), central macular thickness (CMT), and SFCT were measured using spectral-domain optical coherence tomography at baseline and at 1, 3, and 6 months post-treatment. Repeated measures ANOVA and Spearman correlation analyses were performed.To account for the correlation between paired eyes from patients with bilateral involvement, data were analyzed using generalized estimating equations (GEE).

At 6 months post-treatment, significant improvements were observed in logMAR BCVA (0.61 ± 0.25 to 0.33 ± 0.23, P < 0.001) and CMT (466.25 ± 129.85 to 279.41 ± 72.47 μm, P < 0.001). SFCT decreased progressively from 379.65 ± 60.59 μm at baseline to 304.63 ± 53.92 μm at 6 months (P < 0.001). No significant differences in SFCT were observed between NPDR-ME and PDR-ME groups at any time point (P > 0.05). BCVA at 6 months correlated significantly with baseline and post-treatment BCVA and CMT (P < 0.05) but not with SFCT at any time point (P > 0.05).

Intravitreal Conbercept significantly reduces subfoveal choroidal thickness in DME eyes, accompanied by improved visual acuity and reduced macular edema. The lack of correlation between SFCT changes and visual outcomes suggests that choroidal thickness may not directly reflect functional improvement.