Assessment of Foveal Avascular Zone (FAZ) Area in Normal and Diabetic Retinopathy Eyes using OCT Angiography (OCTA)

Abstract

Purpose : OCT Angiography (OCTA) en face images generated by AngioVue software provide high-resolution fine vasculature detail of the retina. The FAZ is known to be affected by pathology such as diabetic retinopathy. The purpose of this study is to compare the performance of the non-flow area measurement tool for FAZ area measurement in Normal and Diabetic Retinopathy eyes, and to explore FAZ areas distribution in the two groups.

Methods : OCTA en face images were acquired with AngioVue software on Avanti SD-OCT systems (Optovue, Fremont, CA) from consented subjects enrolled in the IRB-approved study. 16 Normal eyes and 17 eyes clinically diagnosed with Diabetic Retinopathy were used for analysis. FAZ area measurement is generated automatically by the software, following the user-pointed click inside the FAZ. Repeatability assessment was performed on 3mm x 3mm enface images (2 same-session scans) generated from retinal superficial layer (from ILM to IPL) with maximum intensity projection (MIP) methods. Descriptive statistics of the Normal and Diabetic eyes FAZ distribution were calculated based on averaged FAZ area derived from the two scans.

Results : Mean age was 62 and 55 years; there were 8 out of 16 males and 11 out of 17 males; and 7 right eyes out of 16, and 6 out of 17 in the Normal and Diabetic groups accordingly. The intraclass correlation coefficient (ICC) for repeat scans was 0.964 for Normal eyes and 0.969 for Diabetic eyes. Normal eyes mean FAZ area was 0.28 mm² (range 0.08 – 0.46 mm², STDV 0.08 mm²), with median of 0.28 mm² (Q1:Q3 of 0.23 mm²: 0.33 mm²). Diabetic eyes mean FAZ area was 0.35 mm² (range 0.07 - 0.81 mm², STDV 0.16 mm²), with median of 0.33 mm² (Q1:Q3 of 0.28:0.39 mm²).

Conclusions : The FAZ area can be measured from OCTA en face images generated by AngioVue with good repeatability in both Normal and Diabetic eyes. As expected, the FAZ area distribution range is wider in diabetic retinopathy eyes. Good repeatability suggests that the OCTA images and the AngioAnalytics non-flow area measurement tool can possibly be utilized for non-invasive baseline and follow-up assessments of the FAZ in diabetic patients.

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

 

Repeat scans with FAZ area measurement in Normal (top row) and Diabetic Retinopathy (bottom row) eyes.