Profile of non-responder and late responder patients treated for diabetic macular edema: systemic and ocular factors.

Diabetic macular edema (DME) treatment represents a challenge for the ophthalmologists, and several aspects of real treatment expectancy are still being discussed and not yet fully elucidated. A univocal definition of responsiveness to treatment has not been reached. How the clinicians can evaluate the therapeutic success? The evaluation of systemic and ocular factors should help in this complex management. The age influences the long-term outcomes, and the role of glycemic control is confounded by contrasting correlations between hemoglobin glycated A1c and DME. Long-term treatment success is influenced by baseline best-corrected visual acuity (BCVA), central macular thickness (CMT) and early BCVA response. Also baseline diabetic retinopathy severity scale score is useful to evaluate the chances of improvement before and during treatments. The time-switching was influenced by early BCVA response, however considering a delayed response in a percentage of patients. Several structural optical coherence tomography (OCT) findings could predict long-term success, as the presence of serous retinal detachment, hyperreflective retinal spots, the disruption of external limiting membrane and ellipsoid zone, the disorganization of inner retinal layers and continued increase in CMT were considered predictors of poor response to treatment. Foveal avascular zone enlargement, high number of microaneurysms (Mas), lower vessel density (VD) in deep capillary plexus and lower parafoveal VD in superficial capillary plexus were considered as OCT angiography biomarkers of poor responsiveness. The aim of this review is to report the factors that could influence the response to treatment of DME patients.