Abstract
Purpose :
Central retinal vein occlusion (CRVO) is a common cause of visual loss. Asymmetry among the 4 ETDRS quadrants (superior [SUP], nasal [NAS], inferior [INF] temporal [TEMP]) in terms of optical coherence tomography angiography (OCTA) metrics (e.g., superficial retinal layer [SRL] perfusion density [PD, total area of perfused vasculature/unit area], vessel density [VD, total length of perfused vasculature/unit area] inner thickness [IT] and outer thickness [OT]) exists in control eyes. Herein, we assess if the insult of a non-ischemic versus ischemic CRVO affects the quadrant asymmetry (QA) differentially.
Methods :
28 control eyes, 6 non-ischemic and 7 ischemic CRVO eyes underwent 3x3 mm OCTA scans with signal strength >7. Automated segmented scans with registration for the SRL. QA was defined as the maximum value among the 4 ETDRS quadrants minus the minimum value for a given eye. OCTA parameters were assessed by multivariate linear regression analysis including fixed effects for each individual-by-eye.
Results :
There was no significant QA for the 4 OCTA metrics when comparing non-ischemic CRVO with control eyes (p>0.05). However, ischemic CRVO eyes had greater PD QA (+0.014, p=0.006), IT QA (+20.7, p<0.001) and OT QA (+6.3, p<0.001) than control eyes. Ischemic CRVO eyes had greater VD QA (+1.48, p<0.001), PD QA (+0.030, p=0.003), IT QA (+43.3, p<0.001) and OT QA (+17.6, p<0.001) than non-ischemic CRVO eyes. Within control eyes, OCTA metrics tended to be greatest in NAS, with INF and SUP having lower VD (2.55, p=0.001; 1.54, p=0.002), PD (0.04, p=0.001; 0.02, p=0.011), IT (10, p<0.001; 14.8, p<0.001) and OT (29.6, p<0.001; 32.0, p<0.001), and TEMP having lower IT (5.2, p=0.008) and OT (17.7, p<0.001). In contrast, in CRVO eyes, the max quadrant was not consistent (p>0.05) aside from NAS IT in non-ischemic CRVO eyes higher than INF (6.8, p=0.041) and SUP (10.3, p=0.015) and NAS OT in ischemic CRVO eyes higher than INF (30, p=0.008) and SUP (39.1, p=0.003).
Conclusions :
Although QA does not differ between nonischemic CRVO and control eyes, ischemic CRVO affects PD, VD, IT and OT more asymmetrically across the 4 ETDRS quadrants when compared to non-ischemic CRVO eyes, and affects PD, IT and OT more asymmetrically than control eyes. QA of OCTA metrics in control eyes tended to driven by the largest values found in the nasal quadrant, but were more evenly distributed in CRVO eyes.
This is a 2021 ARVO Annual Meeting abstract.