Abstract
Purpose :
Diabetic retinopathy severity is evaluated using color fundus photographs (FP) employing the Early Treatment Diabetic Retinopathy Severity (ETDRS) scale. Optical Coherence Tomography Angiography (OCTA) is a recently developed imaging technique that generates volumetric angiography including an enface view of the retinal vascular plexus. Our goal was to assess the correlation between automatically generated vascular density from OCTA and ETDRS severity from FP in eyes with diabetic retinopathy.
Methods :
OCTA images (Optovue) of eyes with diabetic retinopathy were captured using the 6x6 scan protocol. Vascular density was generated in the fovea, parafovea and perifoveal regions using the superficial layer segmentation. OCTA quality assessment was performed to assess reliability of the vascular density measurements. Two step grading with adjudication on modified 7 field or 4 wide color fundus images were analyzed for ETDRS severity.
Results :
OCTA and FP were collected on 49 eyes of 34 participants. Twenty (41%) of the OCTA scans were ungradable for vascular density. Of the 29 eyes with acceptable vascular density quality, the mean vascular density was 20.26 in the fovea, 43.38 in the parafovea and 44.06 in the perifovea region. The corresponding color photographs had 8 (28%) in the mild-moderate non proliferative diabetic retinopathy (NPDR) category, 19 (65%) in moderately severe to severe NPDR category and 2 (7%) with proliferative DR. The mean foveal vascular density in eyes with mild-moderate NPDR was 21.29 (SD8.73), moderately severe – severe NPDR was 20.39 (SD5.86) and PDR 14.9 (SD12.87). The corresponding values for parafoveal vascular density was 45.36 (SD7.39), 43.26 (SD5.34) and 36.55 (SD7.99) respectively. Mean perifoveal vascular density was 46.92 (SD4.29), 43.18 (SD4.69) and 40.95(SD7.43) respectively in three categories of DR severity.
Conclusions :
The quality of OCTA image collection is critical in exploring the utility of OCTA in clinical trial outcome analysis. Vascular density is significantly different between eyes with NPDR and PDR. There is a trend towards a drop in vascular density in eyes with NPDR with worsening severity. Large scale trials are needed to identify the potential role of vascular density in predicting DR progression.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.