The alterations of microvascular structure in branch retinal vein occlusion eyes before and after anti-vascular endothelial growth factor drug therapy

Abstract

Objective To observe the alterations of microvascular structure in patients with macular edema (ME) associated with branch retinal vein occlusion (BRVO) before and after anti-VEGF drug therapy. Methods A retrospective case study. Thirty-two eyes of 32 patients with unilateral BRVO-ME at Department of Ophthalmology in Beijing Hospital during November 2016 to June 2018 were enrolled in this study. There were 14 males (14 eyes) and 18 females (18 eyes), with the mean age of 57.81±10.58 years, and the mean course of the disease of 12.13±7.13 d. The affected eyes was defined as the eyes with BRVO-ME. All the affected eyes received intravitreal anti-VEGF drug injections (3+PRN). BCVA and OCT angiography (OCTA) were performed on the BRVO and fellow eyes before and after intravitreal anti-VEGF drug injections. The scanning region in the macular area was 3 mm×3 mm. Macular blood flow density in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), macular hemodynamics parameters [foveal avascular area (FAZ) area, perimeter (PERIM), acircularity index (AI) and vessel density within a 300um width ring surrounding the FAZ (FD-300)] and central retinal thickness (CRT) were measured in all eyes. Paired samples t-test and Univariate Linear Regression were used in this study. Results Comparing with fellow eyes, the mean macular blood flow density measured in the entire scan was lower in BRVO-ME eyes in the SCP (t=6.589, P=0.000) and DCP (t=9.753, P=0.000), PERIM (t=4.054, P=0.000) ), AI enlarged in BRVO-ME eyes (t=4.988, P=0.000), FD- 300 was lower in BRVO-ME eyes (t=2.963, P=0.006), FAZ area enlarged in BRVO-ME eyes (t=0.928, P=0.361). The blood flow density in the DCP was the parameter most significantly correlated with BCVA and FAZ area (r=0.462, −0.387; P 0.05). The blood flow density in the SCP decreased (t=2.814, P<0.05), but the blood flow density in the DCP was not changed significantly (t=0.661, P=0.514). Contrarily, comparing with after 1 anti- VEGF drug injection, the blood flow density in the DCP increased after 2 anti-VEGF drug injections (t=3.132, P<0.05). FAZ area enlarged in BRVO-ME eyes (t=5.340, P<0.001). Comparing with last anti-VEGF drug injection, FAZ area enlarged after every anti-VEGF drug injection (t=2.907, 3.742, 2.203; P<0.05). Conclusions In BRVO-ME eyes, the blood flow density in the SCP and DCP are decreased. The blood flow density in the DCP is positively correlated with BCVA and negatively correlated with FAZ area. After anti- VEGF drug therapy, the blood flow density is decreased in the SCP and increased in the DCP, FAZ area enlarged gradually, PERIM and AI are not changed significantly. Key words: Retinal vein occlusion/therapy; Macular edema/therapy; Angiogenesis inhibitors/therapeutic use; Tomography, optical coherence; Regional blood flow