Development and Application of a Normative Database for OCTA Retinal Vasculature Measurements

Abstract

Purpose : Retinal vasculature is altered in both ocular and systemic diseases, though current gold standard vascular imaging (fluorescein angiography) is not routinely used in the normal population due to the risk of adverse events. The lack of normative data complicates the detection of abnormal vascular patterns. Optical coherence tomography angiography (OCTA) allows for noninvasive measurement of the retinal vasculature. Here we describe the development and application of a normative database of parafoveal capillary density using OCTA.

Methods : Using the Optovue Avanti, two 3x3 mm macular OCTA scans were acquired in both eyes of 146 subjects (aged 8 to 84 yrs). Average percent density of the superficial and deep vessel layers was exported for each scan using the AngioRevue software for subsequent analyses (reliability and interocular symmetry). We created a normative superficial vessel density map using the right eye data for all 146 subjects. Deviation maps were created for 11 subjects with disrupted vasculature (albinism, diabetic retinopathy, vein occlusion, central serious retinopathy, MacTel) which highlight areas of abnormal vessel density (≥ 3 stdev from the mean).

Results : For repeated scans, we observed moderate agreement for vessel density measures of the superficial (ICC=0.755) and deep (ICC=0.661) layer. We observed significant interocular asymmetry for the deep (p =.0011) but not the superficial layer (p =.1627). Signal strength was associated with significantly higher superficial and deep vessel density values (p <.0001). The automated deviation mapping identified multiple regions of abnormal superficial density in each of the subjects with retinal disease.

Conclusions : We created a normative database of parafoveal vessel density using OCTA. Care should be taken interpreting measures of vessel density, given their correlation with signal strength. Our deviation mapping technique provides an efficient way to identify areas of abnormal retinal vasculature, though whether these areas represent true pathology or are artifacts of poor segmentation is not always apparent (see Figure).

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

OCTA images (top) and deviation maps (bottom), with the red areas indicating abnormal vessel density. Shown are images from the right eye of a subject with MacTel (left) and one with oculocutaneous albinism (right). Outer retinal damge in the MacTel retina likely underlies the abnormality temporal to the fovea.