Optic coherence tomography angiography to evaluate preoperative intravitreal Conbercept before vitrectomy for proliferative diabetic retinopathy (PDR)

Abstract

Purpose : To evaluate the change of fibrovascular membranes (FVM) of patients with PDR receiving preoperative intravitreal injection of Conbercept.

Methods : This is a pilot study for PDR patients who received intravitreal Conbercept 7 days before pars plana vitrectomy. The included patients should be with visible FVM available for imaging obtaining by optical coherence tomagraphy angiography (OCTA) pre- (Vpre), 1 day (V1), 3 day (V3), 5 day (V5), and 7 day (V7) post-injeciton. Image segmentation and binarizaiton was performed for vascular density and image skeleton extraction was performed for total length of neovascularization (Figure 1). The FVM size was measured by connecting marked new vessels (disjunctive or interacting vessels, Figure 1) and the FVM height as the length between FVM to inner limiting membrane. The extent of tractional retinal detachment (TRD) was also analyzed by measuring the height between layers of outer segment and retinal pigment epithelia. Each parameters was compared between two consecutive visits (for example, V1 vs Vpre, V3 vs V1, independent t test).

Results : Of the 185 PDR patients, 15 patients (8.11%) were included for OCTA monitoring. The total length of neovascularization was 54.57 ± 38.9 mm for Vpre, 37.60 ± 24.24 mm for V1 (p = 0.003), 33.71 ± 22.86 mm for V3 (p = 0.009), 30.52 ± 21.27 mm for V5 (p = 0.07) and 28.47 ± 19.84 mm for V7 (p = 0.02) (Figure 1). The vascular density reduced from 0.111 ± 0.071 to 0.078 ± 0.044 at V1 (p = 0.009), 0.069 ± 0.043 at V3 (p = 0.028) while the change from V3 to V5 and V7 was not statistically significant. The FVM size reduce from 5.68 ± 3.09 mm² to 5.48 ± 3.01 mm² at V1 (p = 0.02), and 5.409 ± 2.98 mm² at V3 (p = 0.003) while the change from V3 to V5 and V7 was also not statistically significant. There was no different between each visits for FVM height and the extent of TRD (10 patients with TRD).

Conclusions : OCTA facilitates the monitoring and quantification of the anti-neovascularizaiton effect of preoperative use of anti-VEGF drug before vitrectomy for patients with PDR. The effect of anti-neovasularization for PDR patients is remarkable within 3 days, especially 1 day after injection while the effect seems to come to a plateau phase after 3 days, which indicates that preoperative anti-VEGF drug can be used within 3 days pre-vitrectomy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.