Longitudinal Assessment of Intraretinal Microvascular Abnormalities in Diabetic Retinopathy Using Swept-Source Optical Coherence Tomography Angiography

PURPOSE . To longitudinally investigate the changes in intraretinal microvascular abnormalities (IRMAs) over time, employing swept-source optical coherence tomography angiography in eyes with diabetic retinopathy. METHODS . In this retrospective, longitudinal study, we evaluated 12 x 12-mm swept-source optical coherence tomography angiography centered on the macula at baseline and last available follow-up visit for (1) IRMA changes during follow-up, defined as (a) stable, (b) regressed, (c) obliterated, and (d) progressed; and the (2) development of new neovascularization (NV) and their origins. Competing-risk survival analysis was used to assess the factors associated with these changes. RESULTS . In total, 195 eyes from 131 participants with diabetic retinopathy were included. Stable, regressed, obliterated, and progressed IRMA were observed in 65.1%, 12.8%, 11.3%, and 19% of eyes with diabetic retinopathy, respectively. Anti-VEGF injections during the follow-up periods and a slower increase of foveal avascular zone were associated with IRMA regression (P P < 0.001 and P = 0.039). Obliterated IRMA were correlated with previous panretinal photocoagulation (P P < 0.001) and a lower deep capillary plexus vessel density at baseline (P = 0.007), as well as with follow-up antiVEGF injections (P = 0.025). A higher baseline ischemia index (ISI) and panretinal photocoagulation during the follow-up periods were associated with IRMA progression (P = 0.049 and P < 0.001). A faster increase in ISI predicted the development of NV elsewhere (NVE) from veins ( P < 0.001). No significant factors were found to be associated with NVE originating from IRMA. CONCLUSIONS . Changes in IRMA closely correlated with the severity of retinal ischemia and treatment. Notably, our study confirmed the potential, yet relatively rare, development of NVE from IRMA in a large cohort; however, the risk factors associated with this transformation require further exploration.