Long-term real-world outcomes of retinal microvasculature changes in proliferative diabetic retinopathy treated with panretinal photocoagulation vs. intravitreal conbercept

Purpose: To compare long-term real-world outcomes of retinal microvasculature changes in proliferative diabetic retinopathy (PDR) treated with panretinal photocoagulation (PRP) vs. intravitreal conbercept (IVC) and to explore the potential factors affecting these changes.Methods: This study retrospectively included 96 treatment-naive PDR eyes of 96 type 2 diabetes mellitus patients [59 PRP and 37 IVC]. Baseline characteristics and treatment details were collected. Optical coherence tomography angiography (OCTA) data of macular vessel density (VD) and optic disc capillary density (CD) at baseline and at the last follow-up were compared between groups. The differences between the baseline and the last follow-up OCTA data in each group were also tested for significance. The correlation between the change in each OCTA parameter from baseline and each baseline characteristic/treatment parameter was investigated in each group. Results: During a mean follow-up of two years, greater superficial (SCP) (p = 0.004) and deep capillary plexus (DCP) VD (p < 0.001) were observed in the foveal area in the PRP than in the IVC. Compared to the baseline, SCP VD in the foveal area increased in the PRP (p = 0.012), while an increased SCP VD in some sectors in the parafoveal and perifoveal areas (p < 0.05), rather than the foveal area (p = 0.908), was seen in the IVC. For both groups, eyes with a higher VD/CD at baseline tended to develop capillary dropout more intensively (all p < 0.05). In the IVC group, foveal avascular zone (FAZ) area change showed a negative correlation with baseline FAZ area (p = 0.020), and complementary PRP exerted a negative influence on FAZ area change (p = 0.002). In the PRP group, SCP VD change was positively correlated with follow-up frequency, and was negatively correlated with diastolic blood pressure (all p < 0.05); DCP VD change showed a positive correlation with PRP shot number (p = 0.019).Conclusion: The aforementioned microvasculature changes should be considered when PRP or IVC is adopted in PDR long-term management.