Optical Coherence Tomography Angiography Features of Diabetic Retinopathy

Abstract

Purpose To describe the optical coherence tomography (OCT) angiography features of diabetic retinopathy Methods Using a 70kHz OCT and the split-spectrum amplitude decorrelation angiography (SSADA) algorithm, 6 × 6 mm 3-dimensional angiograms of the macula of 4 patients with diabetic retinopathy were obtained and compared with fluorescein angiography (FA) for features catalogued by the Early Treatment of Diabetic Retinopathy Study. Results OCT angiography detected enlargement and distortion of the foveal avascular zone, retinal capillary dropout, and pruning of arteriolar branches. Areas of capillary loss obscured by fluorescein leakage on FA were more clearly defined on OCT angiography. Some areas of focal leakage on FA that were thought to be microaneurysms were found to be small tufts of neovascularization that extended above the inner limiting membrane. Conclusion OCT angiography does not show leakage, but can better delineate areas of capillary dropout and detect early retinal neovascularization. This new noninvasive angiography technology may be useful for routine surveillance of proliferative and ischemic changes in diabetic retinopathy.

Optical coherence tomography angiography — novel method to access retinal microcirculation in patients with diabetic retinopathy

“…The reason for this discrepancy may be the low blood flow through the microaneurysms or flow of the serum without morphotic elements, which makes detecting them with decorelation method impossible. Numbers of microanerusyms lower than expected while using OCTA examinations were also reported by other authors [6,8,9].…”

“…FA holds an evident advantage in visualizing capillary leaks and microanuerysmal leakiness [6,7]. This is of significance because these signs determine the decision to introduce focal laser therapy or anti-VEGF treatment.…”

“…Previous studies comparing OCTA angiograms with classic FA images show many benefits of the former [6,7]. First of all, OCTA angiograms feature high resolution.…”

“…First of all, OCTA angiograms feature high resolution. Obtained images present an uncanny quality in mapping the smallest capillary network surrounding the macula, which enables a visualization of minimal structural abnormalities [6,8]. This could potentially lead to diagnosing vascular changes in diabetic patients much earlier than it is currently possible, but would also require performing OCTA on a large group of patients [9].…”

Resistive Index of Ophthalmic Artery as a Bioimaging Biomarker for the Severity of Diabetic Retinopathy

“…As per Laplace law, the tension in the vessel wall resisting distension pressure is inversely proportional to the radius of the vessel. The vessel wall tension required to counteract distending pressure is not achieved in a dilated vessel, hence there is a tendency towards dilatation with subsequent hyper perfusion [24]. In addition, several factors, namely, abnormal auto regulation of the retinal circulation [25], increased conductance as an auto regulatory response to retinal ischemia [26], endothelin-1 resistance, inhibition of calcium influx channel in smooth muscle cells and increased activity of nitric oxide synthase also lead to hyper perfusion.…”