Abstract
Purpose :
Swept Source Optical coherence tomography angiography (SS-OCTA) is a novel technique to visualize vascular changes like ischemia in patients with diabetic retinopathy. The aim of this study was to distinguish between areas of ischemia and artifacts, appearing as capillary dropout caused by retinal swelling in diabetic macular edema (DME).
Methods :
In this prospective, cross-sectional study we included 30 patients with DME undergoing standard ophthalmological examination, including OCTA and fluorescein angiography (FA) imaging. The stage of diabetic retinopathy was determined by clinical examination. Quantitative image analysis was performed using swept-source OCT (SS-OCT) scans to determine ischemic areas. All areas presenting capillary dropout within the macula in OCTA images were analyzed and compared to early-phase FA images regarding lesion appearance and dimension. The images were evaluated by two well-trained investigators.
Results :
The cystoid spaces in DME created a false negative capillary dropout compared with ischemic areas on FA images. Hence DME imposed as capillary non perfusion in some SS-OCTA images. The artifacts presented with irregular, blurred borders and a greyish shade of color. In contrast, areas of non-perfusion followed the anatomic morphology of capillaries and presented with regular borders and a black shade of color. Artifacts in SS-OCTA were mainly seen either below cystoid lesions in the macular center or in the scan periphery in areas with reduced OCT signal strength.
Conclusions :
The novel technique of SS-OCTA provides valuable information about capillary perfusion status using a non-invasive approach. Artifacts caused by DME must be differentiated from true capillary dropout. In OCTA images, capillary non-perfusion can be differentiated from artifacts secondary to retinal swelling by the appearance of the vascular network and the degree of OCT signal strength.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.