Purpose
To describe a novel method of identifying retinal vascular microaneurysms (MAs) in nonproliferative diabetic retinopathy (NPDR) using swept source optical coherence tomography (SS-OCT)
Methods
SS-OCT images were acquired in 17 eyes with NPDR using a prototype SS-OCT device with a laser wavelength centered at 1060 nm and an acquisition speed of 100,000 A-scans/sec. 3 x 3 x 3 mm raster scans were obtained centered on the fovea (512 A-scans/B-scan, 512 B-scans/cube, 1500 pixels of depth). Sequential restricted summed voxel projections, or "slabs," were created with a thickness of 4 μm through the cube and the images registered with intravenous fluorescein angiography (FA) images obtained at the same visit. MAs were identified on SS-OCT slabs and correlated to MAs identified on FA images.
Results
MAs were identified in SS-OCT slabs in 15 of 17 eyes, resulting in a NPDR diagnosis rate of 88%.<br /> <br /> A mean of 20.9 slabs (SD 3.0) were analyzed in each eye. The mean number of MAs identified on each FA was 11.7 (SD 11.9, range 1-38). The mean number of MAs identified via SS-OCT slabs was 8.1 per cube (SD 9.3, range 0-30); 62.7% (SD 31, range 0-100). The two cases with no SS-OCT MA detection had only one MA identified on FA. Ultimately, 68.84% of MAs were identified via SS-OCT slabs.
Conclusions
SS-OCT visualization of MAs could serve as a tool for the diagnosis of NPDR. This technique should be explored in larger studies. It may also be possible to apply this SS-OCT imaging biomarker for population-based diabetic retinopathy screening initiatives.