Abstract
Purpose :
Asymmetry among the ETDRS quadrants on en-face OCTA metrics (superficial [SRL] and deep retinal layer [DRL] perfusion density [PD] and vessel density [VD]) allows for intra-eye comparisons and possibly mitigates inter-eye variabilities such as refractive error, age, axial length, and magnification. Herein, we assess the effect of the level of diabetic retinopathy (DR) on quadrant asymmetry (QA) with en-face OCTA
Methods :
90 eyes (60 patients) [27 non-diabetic (noDM); 12 diabetics without DR (noDR); 11 mild, 10 moderate (mod) and 7 severe (sev) non-proliferative DR (NPDR); and 23 proliferative DR (PDR)] underwent 3x3mm OCTA scans (signal >7, fovea-centered and auto-segmented for SRL/DRL). QA was defined as the max-min value among 4 ETDRS quadrants for a given eye in terms of OCTA metrics for the SRL and DRL and was compared to DR severity by linear regression including fixed effects for each individual eye
Results :
Mean age was 55.5 years (range 24-88) with 60% male. QA for SRL VD was 1.87, 1.95, 1.69, 2.37, 2.38 and 3.13 for noDM, noDR, mild, mod, sev and PDR, respectively. QA for SRL PD was 0.028, 0.035, 0.028, 0.046, 0.045 and 0.061, for DRL VD was 2.17, 1.76, 1.78, 2.38, 2.90 and 3.25, and for DRL PD was 0.037, 0.036, 0.033, 0.056, 0.071 and 0.069 for noDM, noDR, mild, mod, sev and PDR, respectively. Linear regression demonstrated for every step increase in DR severity, there was a 0.34 increase in QA (p<0.001) for SRL VD, +0.008 SRL PD (p<0.001), +0.41 DRL VD (p<0.001), and +0.010 DRL PD (p<0.001). QA for both SRL VD and PD were significantly higher in eyes with sev or PDR when compared to noDM or noDR eyes (+0.23 and +0.004, p<0.001). QA for both DRL VD and PD were significantly higher in eyes with mild or mod when compared to noDM or noDR eyes (+0.15, p=0.04 and +0.003, p=0.02)
Conclusions :
DR severity affects PD and VD more asymmetrically across the 4 ETDRS quadrants with a linear increase in QA for each worsening level of DR. Clinically significant increase in QA occurs when eyes are worse than mod NPDR in the SRL and > mild NPDR in the DRL. Individual intra-eye metrics such as QA can be utilized to quantify DR severity without concerns for inter-eye variabilities that could affect the reproducibility and reliability of OCTA quantification
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.