Swept-source OCTA quantification of capillary closure predicts ETDRS severity staging of NPDR

Purpose To test whether a single or composite set of parameters evaluated with optical coherence tomography angiography (OCTA), representing retinal capillary closure, can predict non-proliferative diabetic retinopathy (NPDR) staging according to the gold standard ETDRS grading scheme. Methods 105 patients with diabetes, either without retinopathy or with different degrees of retinopathy (NPDR up to ETDRS grade 53), were prospectively evaluated using swept-source OCTA (SS-OCTA, PlexElite, Carl Zeiss Meditec) with 15x9 mm and 3x3 mm angiography protocols. Seven-field photographs of the fundus were obtained for ETDRS staging. Eyes from age-matched healthy subjects were also imaged as control. Results In eyes of patients with type 2 diabetes without retinopathy or ETDRS levels 20 and 35, retinal capillary closure was in the macular area, with predominant alterations in the parafoveal retinal circulation (inner ring). Retinal capillary closure in ETDRS stages 43-53 becomes predominant in the retinal midperiphery with vessel density average values of 25.2 +/- 7.9 (p=0.001) in ETDRS 43 and 23.5 +/- 3.4 (p=0.001) in ETDRS 47-53, when evaluating extended areas of 15x9 protocol. Combination of acquisition protocols 3x3 mm and 15x9 mm, using SS-OCTA, allows discrimination between eyes with mild NPDR (ETDRS 10, 20, 35) and eyes with moderate-to-severe NPDR (ETDRS grades 43-53). Conclusions Retinal capillary closure, quantified by SS-OCTA, can identify NPDR severity progression. It is located mainly in the perifoveal retinal capillary circulation in the initial stages of NPDR, whereas the retinal midperiphery is predominantly affected in moderate-to-severe NPDR.

Automated summary

This study used OCTA to analyze retinal capillary closure in eyes of diabetic patients, finding that it can predict the severity of NPDR. A smart combination of different imaging protocols effectively differentiated between mild and moderate-to-severe NPDR.