Abstract
Purpose :
Retinal artery occlusions (RAO) or vein occlusion (RVO) lead to ischemia and intracellular edema of the retina. Transparency decreases, which changes SD-OCT retinal reflectivity (RRF). We examined this RRF in healthy eyes and eyes with RAO and ischemic or non-ischemic RVO. Can those changes be used to measure the level of ischemia in the inner retina? Is there a correlation between angiographically identified ischemia and OCT detected one?
Methods :
Retrospective evaluation of 100 eyes with branch or central RAO and 34 eyes with branch or central RVO. Fluorescein-angiography (FAG) distinguished between ischemic and non-ischemic RVO. SD-OCT-scans were exported as black-on-white-JPEG-pictures to Adobe Photoshop. Areas of vitreous body (VB), ganglion cell layer (GC), inner plexiform layer (IPL) und outer nuclear layer (ONL) 1000µm away from the fovea were marked and mean gray scale calculated to quantify RRF (0: black, high reflectivity; 255: white, low reflectivity). Comparison of RRF with healthy partner eyes (Student‘s t-test, double-sided, heteroskedastic; p<0.05 chosen as statistically significant). OCT software’s built-in measuring tool quantified ischemic area, using the picture with the largest seen ischemic area.
Results :
Given are grayscale values of different layers in healthy eyes, non-ischemic and ischemic RVO and RAO. RRF of VB did not differ significantly (247; 250; 246; 245; p>0.05). GC and IPL RRF increased. Differences where significant between healthy and all forms of occlusion (GC: 160; 128; 102; 97; p<0.05; IPL: 189; 160; 147; 145; p<0.05) and between RAO, non-ischemic and ischemic RVO, but not between non-ischemic and ischemic RVO (p=0.63 und p=0.24). ONL RRF did not differ (225; 235; 238; 233; p>0.05). Inner layer RRF correlates only weakly with ischemic area in FAG (r=-0.46).
Conclusions :
In RAO or RVO, SD-OCT-measured RRF changes in inner retinal layers according to the type and severity of occlusion (RAO > ischemic RVO > non-ischemic RVO) and therefore presumably to the level of ischemia. Vitreous body or outer nuclear layer RRF do not change and might be used for scaling purposes. According to this study, OCT can detect different levels of ischemic changes in the retina, although there only is weak correlation between RRF changes and ischemic areas.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.