Patterns of Peripheral Retinal and Central Macula Ischemia in Diabetic Retinopathy as Evaluated by Ultra Widefield Fluorescein Angiography

Abstract

Purpose: To investigate the association between peripheral and central ischemia and vascular leakage in diabetic retinopathy.

Methods: Consecutive ultra widefield fluorescein angiography (uwFA) images were collected from patients with diabetes over a 12-month period. Areas of capillary non perfusion and leakage were quantified in the peripheral retina and central macula. Parameters quantified included the foveal avascular zone (FAZ) area, peripheral ischemic index, peripheral leakage index, and central retinal thickness measurements, and visual acuity. A high peripheral ischemia or leakage index was defined as an area of capillary non perfusion or leakage that was >50% of the total retina area visualized on uwFA. Optical coherence tomography foveal scans were used to derive central retinal thickness measurements.

Results: 47 eyes of 47 patients were included. A moderate correlation was observed between the peripheral ischemia index and FAZ area, both in all eyes (r=0.49, p=0.0001) and in eyes that were laser naive (r=0.55, p=0.003). A moderate correlation was also observed between the peripheral leakage index and FAZ area, but only in eyes that were laser naive (r=0.44, p=0.02). A thinner retina was observed in eyes with macular ischemia (217 ± 81.8μm versus 272 ± 36.0μm) (p=0.02), but not peripheral ischemia. Similarly, a significant correlation was found between visual acuity and FAZ area (r=0.53, p=0.0002), but not with peripheral ischemia or leakage indices.

Conclusions: uwFA provides an insight into the relationships between diabetic vascular complications in the retinal periphery and central macula. Although we observed relationships between ischemia and vascular leakage in the macula and periphery, it was only macular ischemia that was independently associated with a reduced visual function that was further accompanied by retinal thinning.

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 499 diabetic retinopathy • 498 diabetes