Optical coherence tomographic characteristics of microaneurysms in diabetic retinopathy

Purpose To characterize microaneurysms in diabetic retinopathy (DR) depicted by spectral-domain optical coherence tomography (SD-OCT). Design Retrospective, observational case series. Methods We surveyed a consecutive series of 76 eyes from 60 patients with DR (22 mild nonproliferative diabetic retinopathy [NPDR]; 43 moderate NPDR; 9 severe NPDR; 2 proliferative diabetic retinopathy [PDR]) who underwent Spectralis OCT, fluorescein angiography (FA), and color fundus photography on the same day. The microaneurysms on OCT were oval and well demarcated at the points where those on color fundus photographs and FA were delineated. The characteristics of microaneurysms were evaluated. Results Based on the status of the capsular structure shown in the sectional images of OCT (called ring sign), we classified 147 microaneurysms depicted by all of SD-OCT, FA, and color fundus photographs in 76 eyes: 28 with complete ring sign, 54 with incomplete one, and 65 with no structure. Microaneurysms with no ring sign had hyperreflective spots in the lumen and were accompanied by nearby cystoid spaces more frequently than other types ( P = .033 and P = .007). Thirteen of 75 microaneurysms with nearby cystoid spaces protruded into the cystoid spaces, and 11 of those 13 microaneurysms presented with no ring sign. Microaneurysms resided mainly in the inner nuclear layer (INL) (80.3%), and 65 of such microaneurysms (55.1%) were accompanied by nearby cystoid spaces. Conclusions SD-OCT delineated the capsular structure, hyperreflective spots, and location of microaneurysms, and microaneurysms with the ring sign were positively correlated with nearby cystoid spaces and protrusion into the cystoid spaces.