Quantitative Assessment of Retinal Capillary Network in Diabetic Retinopathy with Optical Coherence Tomography Angiography

Abstract

Purpose : A couple of publications have reported case series of diabetic retinopathy (DR) examined by optical coherence angiography (OCT-A). However, automated method for quantitative assessment of capillary bed is still lacking. We developed a prototype automated analysis system to quantify and measure retinal capillary network from OCT-angiograms, and examined the associations of the OCT-A measures with different DR severity and hyperglycemia in a cohort with diabetes (DM).

Methods : We conducted a prospective, observational clinical study of Chinese patients with DM. Dilated fundus examination was accessed for DR severity. All patients underwent OCT-A with a swept-source-OCT (DRI-OCT Triton, Topcon) with a scan area of 3mmx3mm containing 256×256 A-scans. En face images for superficial and deep capillary plexus were generated by the Triton build-in software. Foveal avascular zone area, total capillary dropout area and microvascular density for each capillary plexus image were automatically measured by our customized image analysis program. We used analyses of covariance and test of trend to determine the associations of DR severity with OCT-A measures.

Results : A total of 50 eyes from 50 patients with DM were included. The mean (SD) age was 65.9 (12.4) years and duration of DM was 13.4 (9.54) years, respectively. Increased DR severity level was significantly associated with larger total capillary dropout area (p-trend=0.020), larger foveal avascular zone area (p-trend=0.046) and lower microvascular density (p-trend=0.020) in the superficial capillary plexus, and larger total capillary dropout area (p-trend=0.017) and lower microvascular density (p-trend=0.017) in the deep capillary plexus, while controlling for age, gender, HbA_1c, duration of DM, body mass index, blood pressure and hypercholesterolemia. In the multiple linear regression analysis, each 1% increase in HbA_1c level was associated with 0.079mm² of total capillary area enlargement (p=0.047) and 0.081% microvascular density decrease (p=0.047) in the superficial capillary plexus.

Conclusions : Loss of macular capillary bed can be quantitatively measured from OCT-angiograms and shows association with retinopathy severity and hyperglycemia in patients with DM.

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

 

Microvascular density maps generated by a customized program in no DR, mild and moderate NPDR in superficial (A-C), and in deep capillary plexus (D-F), respectively.