Novel OCT angiography parameters for analyzing microvascular changes in proliferative diabetic retinopathy after...

To evaluate the effects of intravitreal Conbercept (IVC) loading injections on proliferative diabetic retinopathy (PDR) retinal microvasculature using novel optical coherence tomography angiography (OCTA) parameters.

This retrospective study included 25 eyes of 25 treatment-naïve PDR patients who received monthly IVC for 3 consecutive months. At baseline and after IVC loading injections, OCTA novel parameters, including vessel skeleton density (VSD), vessel diameter index (VDI), fractal dimension (FD), branch vessel tortuosity (BVT) and percentage area of nonperfusion (PAN), were measured in the superficial capillary plexus (SCP) and deep capillary plexuses (DCP). Best-corrected visual acuity (BCVA), central macular thickness (CMT), and traditional OCTA parameters such as vessel density (VD) and foveal avascular zone (FAZ) metrics were also recorded. Patients were grouped by baseline hemoglobin A1c (HbA1c) (<8 % vs. ≥8 %) for subgroup analysis.

After IVC loading injections, BCVA improved (P = 0.036), and CMT decreased (P < 0.001). SCP-FD, DCP-VSD, and DCP-FD increased (P = 0.023, 0.031,0.036, respectively). Multivariate analysis revealed that baseline SCP-PAN was positively correlated with CMT reduction (β = 1.821, P = 0.016). In HbA1c <8 % group, SCP-VDI, DCP-VSD, and DCP-FD increased (P = 0.022, 0.033, 0.033, respectively) after loading injections.

Novel OCTA parameters revealed that IVC loading injections can improve retinal microvasculature in PDR patients. However, using these novel parameters for follow-up and treatment assessment remains challenging under varying image processing conditions.