Efficacy of conbercept pro re nata (PRN) versus treat-and-extend (T&E) regimens following five initial monthly doses in diabetic macular edema: a 24-month retrospective cohort study.

Objective: This study aimed to observe and compare the visual and anatomical improvements over 24 months in patients with diabetic macular edema (DME) treated with intravitreal conbercept injection following five initial monthly doses, using either a Pro Re Nata (PRN) regimen or a Treat-and-Extend (T&E) regimen. The injection and visit frequency were also compared between the two groups. Methods: This study retrospectively analyzed 119 patients with DME. Sixty patients received the 5+PRN regimen, while the other 59 patients were treated with the 5+T&E regimen. Baseline and post-treatment parameters, including best-corrected visual acuity (BCVA), central foveal thickness (CFT), microaneurysm count (MA count), retinal vein diameter, deep capillary plexus vessel density (DCP-VD), foveal avascular zone (FAZ) area, hard exudate (HE) area, and hemorrhage area, were recorded and compared between the two groups. The total number of intravitreal injections administered within 24 months was documented for both groups. Results: Significant improvements in BCVA, CFT, and MA count were observed as early as 6 months after treatment in both groups, and these improvements were sustained through 24 months. Significant improvements in retinal vein diameter and DCP-VD became evident at 18 months post-treatment. Both the HE area and hemorrhage area showed significant improvements at 24 months after treatment. No statistically significant change in FAZ area was detected during the follow-up period. There were no significant differences in all therapeutic outcomes between the two groups. The mean number of injections within the 24-month follow-up was 14.02 ± 2.05 in the 5+PRN group and 11.44 ± 1.74 in the 5+T&E group. Meanwhile, the average number of follow-up visits was 24.89 ± 1.67 in the 5+PRN group and 13.94 ± 2.60 in the 5+T&E group. Both the injection frequency and follow-up visits were significantly lower in the 5+T&E group than in the 5+PRN group. Conclusion: Conbercept is safe and effective for the treatment of DME. Both the 5+PRN and 5+T&E regimens demonstrated significant improvements in visual acuity and retinal anatomical structure over the 24-month follow-up period. Over 24 months, the 5+T&E group had fewer mean injections and follow-up visits compared with the 5+PRN group, indicating that an individualized dosing strategy can reduce patient burden and healthcare costs while maintaining therapeutic efficacy.