Abstract
Purpose :
The progression of retinal pigment epithelium (RPE) and vasculature degeneration in subjects with retinitis pigmentosa (RP) may not be parallel. To better understand this, we compared optical coherence angiography (OCTA) and fundus autofluorescence (FAF) images from RP patients.
Methods :
Retrospective analysis of retinal images from five randomly selected subjects with RP enrolled in an IRB approved study. Subjects had OCTA (12x12mm scans Plex-Elite 9000 - Carl Zeiss Meditec, Germany) and FAF (Optos-Clarity Medical Systems, CA, USA) as part of their standard of care. Five normal patients served as a control group. Vessel density (VD) (mm/mm2) of the superficial and deep vascular plexus (SP, DP) were obtained with the Macular Density v0.7.1 algorithm (Advanced Retina Imaging ARI Network). For FAF analysis, an ETDRS grid was overlaid on the images and a numerical scoring system (1 normal – 9 total hypoFAF) was used to grade each sector. VD of a sector was classified as abnormal if the average SP & DP measurement was one standard deviation below the control’s median. We estimated the concordance for each sector.
Results :
The RP group had lower VD compared to the control group (SP=10.7 vs 15.8mm-1, p=<0.0001; DP=7.8 vs 11.9mm-1, p=<0.0001). In the RP group, VD was lower in the outer than the inner ring (SP=10.3 vs 11.8mm-1, p=0.28; DP= 7.5 vs 9.0mm-1, p=0.25); outer temporal was lower than outer nasal (SP=7.7 vs 14.6mm-1, p=0.0005; DP=5.6 vs 10.1mm-1, p=0.015) while inferior and superior sectors were similar. In FAF scoring the inner ring was more affected than the outer ring (average score of 5.45 vs 3.8 p=0.03) and there were no significant differences between other FAF sectors. Concordant FAF & VD abnormality was present in 6/8 (75%) sectors (all inner, outer nasal, outer inferior). The other 2/8 (25%) sectors had normal FAF score and abnormal VD (outer superior/temporal). 4/4 (100%) sectors in the inner ring had concordant abnormalities while only 2/4 (50%) sectors in the outer ring.
Conclusions :
This pilot study shows moderate concordance between VD/FAF abnormalities. Our findings suggest vascular & RPE degeneration follow a similar time course in the inner ring sector, but not in the outer. Larger studies are required to explore this finding.
This is a 2020 ARVO Annual Meeting abstract.