Retinal oxygen kinetics, hemodynamics and ocular movement changes after anti-VEGF in retinal vein occlusion through a multimodal imaging system

Abstract

Purpose : This study aims to assess the kinetics of retinal blood oxygen and blood flow, pupillary light responses, and smooth pursuit eye movements (SPEM) in patients with retinal vein occlusion (RVO) treated with anti-VEGF.

Methods : Spectrophotometric retinal oximetry, laser speckle contrast imaging, and pupil and eye movement recorder were conducted using a rapid newly-developed non-invasive multimodal ocular structural-functional imaging system.

Results : This was a cross-sectional study on 48 eyes with RVO treated with anti-VEGF therapy. The study comprised 29, 19 and 31 eyes as branch RVO (BRVO), central RVO (CRVO) and healthy subjects, respectively. After anti-VEGF, 77.7% of BRVO-macular edema (ME) and 100% CRVO-ME were reduced or resolved, and their best-corrected visual acuity improved (p=0.02 and 0.03, respectively). Compared with control group, in both RVO groups, blood pulsation-flow acceleration index and resistivity index were higher, blowout score was lower (p<0.001 or 0.05, respectively); while retinal perfusion-arterial and venous blood flow velocity (BFV) (p<0.01 or 0.05, respectively) and arterial blood flow (volume) (RBF^a) were lower (Picture 1). In BRVO patients, retinal arteriovenous differences of oxygen saturation (SO₂), oxygen concentration (CO₂) and oxygen extraction fraction (OEF) were all higher; and the velocity of SPEM was faster(p<0.05, respectively). In CRVO group, arterial external diameter (ED^a) was smaller (p<0.001); pupil contraction rate, amplitude and velocity were all lower (p<0.05, 0.05 and 0.01, respectively).

Conclusions : There were retinal ischemia and hypoxia conditions in RVO patients with increasing retinal blood flow resistance. Compensatory retinal blood flow and pulsation may not meet the oxygen metabolism. Patients with CRVO had pupil deficiency. Faster velocity of eye movements in BRVO maybe related to saccade caused by central visual defects. This multi-modal ocular imaging system made possible breakthroughs in functional integration in a single system, which will facilitate clinical examinations and be helpful for early-stage diagnoses and interventions.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

(A) Multispectral images of 500, 548, 605 and 810 nm for oxygen kinetics and hemodynamics analyses; (B) Results of oxygen kinetics; (C) Structural and functional changes of blood flow.