Abstract
Purpose :
OCT Angiography (OCTA) of the macula may serve as a diagnostic tool for glaucoma. We compared the ability of macular vessel parameters from 4.5mmx4.5mm scans (“4.5”) and 6mmx6mm scans (“6.0”) to differentiate primary open angle glaucoma (POAG) from normal patients based on quantifications of the entire scan or of an elliptical region (horizontal axes 0.6mm and 2.4mm; vertical axes 0.5mm and 2.0mm) centered on the foveal avascular zone. We hypothesized that the global 6.0 scan parameters would have higher diagnostic accuracy due to inclusion of peripheral areas of the macula.
Methods :
4.5 and 6.0 scans were exported from prototype and commercial spectral domain OCTA, respectively, and processed using custom quantification software to create en face images of the superficial retinal layers on normal (30 eyes, 19 patients) and primary open angle glaucoma (53 eyes, 39 patients; pre-perimetric to severe) eyes. Vessel area density (VAD), vessel skeleton density (VSD), vessel complexity index (VCI), and flux were calculated for the global and elliptical areas (Figure). Area-under-curve (AUC) statistics, controlling for age and inter-eye correlation, were used to determine diagnostic accuracy.
Results :
For the global quantification, the AUC for the 4.5 versus 6.0 scans for VAD was 0.67 (p=0.004) and 0.82 (p=<0.0001), respectively (AUC difference [Δ]: p=0.01); for VSD, 0.68 (p=0.002) versus 0.82 (p<0.0001), [Δ]:p=0.02; for VCI, 0.67 (p=0.0047) versus 0.81 (p<0.0001), [Δ]:p=0.02; for flux, 0.68 (p=0.0024) versus 0.85 (p<0.0001), [Δ]:p=0.01.
For the elliptical quantification, the AUC for 4.5 versus 6.0 scans for VAD was 0.65 (p=0.0188) and 0.73 (p=0.0001), respectively ([Δ]: p=0.19); for VSD, 0.67 (p=0.0043) versus 0.75 (p<0.0001), [Δ]:p=0.24; for VCI, 0.64 (p=0.0225) versus 0.72 (p=0.0002), [Δ]:p=0.24; for flux, 0.63 (p=0.0467) versus 0.73 (p=0.0003), [Δ]:p=0.15.
Conclusions :
All global parameters for the 6.0 scans outperformed those of the 4.5 scans. For the elliptical quantifications, there was a similar trend towards statistical significance. While the 4.5 scans used slightly different prototype image processing methods, it is possible that improved resolution does not improve diagnostic accuracy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.