Abstract
Purpose :
To assess the intrasession repeatability of quantitative retinal vascular metrics using Swept-Source Optical Coherence Tomography Angiography (SS-OCTA) in an Asian sample of adults aged 60 years and above.
Methods :
In this population-based substudy, thirty-two elderly participants (32 randomly selected eyes) underwent imaging with the swept-source OCTA (SS-OCTA; PLEX® Elite 9000, Carl Zeiss Meditec, Inc., Dublin, USA). During one session, each eye underwent 2 repeated scans of 2 scan protocols: a macular-centred 3 x 3-mm2 and a wide-field 12 x 12-mm2 for a total of 4 acquisitions. Foveal avascular zone (FAZ) metrics were obtained from the 3 x 3-mm2 scan using Zeiss’ algorithm. Images of superficial vascular plexuses (SVP) and deep vascular plexuses (DVP) were enhanced by Hessian-based filter, and then thresholded to generate a binarized perfusion map. The perfusion density (PD) was calculated as the ratio of number of bright pixels to the total number of image pixels. The binarized perfusion map was skeletonized to produce a vessel map where vessel length density (VLD) was calculated as the ratio of bright pixels in the vessel map to the total number of image pixels. Intrasession repeatability was assessed with the intraclass correlation coefficient (ICC).
Results :
A total of 32 participants (20 men and 12 women; mean [SD] age, 71 [7] years) underwent evaluation. Of these, 22 eyes (69%) of 3 x 3-mm2 and 12 eyes (38%) of 12 x 12-mm2 had good quality scans and were included in this analysis. Of the 26 eyes analysed, mean Snellen best corrected visual acuity was 20/25 and mean spherical equivalent was +0.08D±1.79. Half of them were diagnosed with ocular conditions including 10 mild cataracts and 2 epiretinal membranes. For FAZ area, the ICC was 0.97 (p<0.001). For 3 x 3-mm2 scans, the ICC of the PD at the SVP and DVP were 0.69 (p=0.006) and 0.93 (p<0.001) whereas the ICC of the VLD at the SVP and DVP were 0.63 (p=0.015) and 0.90 (p<0.001). For 12 x 12-mm2 scans, the ICC of the PD at the SVP and DVP were 0.91 and 0.87 whereas the ICC of the VLD at the SVP and DVP were 0.89 and 0.87 (all p<0.001).
Conclusions :
Quantitative OCTA metrics from the superficial and deep retinal vasculature can be obtained with a high level of repeatability but obtaining high quality widefield scans in an elderly population may be particularly challenging.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.