Purpose: To quantify the preoperative neovascular change pattern on the fibrovascular membrane (FVM) within 7 days after intravitreal injection of conbercept (IVC) using optical coherence tomography angiography (OCTA) in proliferative diabetic retinopathy (PDR).
Methods: Prospective, observational study of PDR patients with visible FVM receiving or not receiving IVC. Neovascular changes were assessed by OCTA pre-IVC and 1, 3, 5, and 7 days post-IVC. Vessel skeleton density (SD) and vessel density (VD) were quantified by an intensity-based optical microangiography algorithm. The interclass correlation coefficient (ICC) was calculated to assess the agreement between measurements. The SD and VD were compared between follow-ups using repeated-measures analysis in the IVC group.
Results: The ICC was 0.992 (95% confidence interval [CI]: 0.982-0.996) for SD and 0.926 (95% CI: 0.838-0.912) for VD of neovascularization. The neovascularization on FVM significantly regressed in the IVC group (n = 16) compared with no IVC (n = 8) (p = 0.001 for SD and p < 0.001 for VD). The comparisons between consecutive follow-ups showed a statistically significant reduction in SD and VD at 1 and 3 days post-IVC. However, from day 3 onward, the SD and VD remained unchanged. There was no development or progression of tractional retinal detachment within the 7-day period after IVC.
Conclusion: OCTA-based quantification of the neovascularization on FVM in PDR is feasible, with high inter-reader agreement. The regression of neovascularization reaches a plateau 3 days after IVC.
Clinical trial registration: This trial is registered with the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , registration number ChiCTR-IPR-17014160).
Keywords: Angio–OCT; Anti-VEGF; Optical coherence tomography angiography (OCTA); Proliferative diabetic retinopathy.