Macular Perfusion in Clinically Significant Diabetic Macular Edema and in Different Stages of Diabetic Retinopathy

Diabetic macular edema uses structural features as biomarkers and predictors of treatment response. Optical coherence tomography angiography (OCTA) metrics found a correlation between many structural biomarkers and reduced vessel density. We present recent references of vessel length density, vessel area density, and foveal avascular zone metrics in eyes with diabetic macular edema and comment on the associations found between them and structural biomarkers. Diabetic macular edema can change the level at which the capillary plexuses are located, with retinal cysts altering the strength signal. Though image evaluation requires adjustment, intra-subject comparison before and after treatment can be a useful tool to note changes in vessel perfusion, combined with structural changes, to assess treatment outcomes. Macular ischemia is a variable that can be identified reliably with OCTA and can be detected in different capillary plexuses. For eyes with retinal thickening, OCTA evaluation requires consistency to avoid inter-device variability. It is recommended to use the same device, the same scanning protocol, and preferably the same software, to obtain more reproducible measurements.