Elevated number and density of macrophage-like cell as a novel inflammation biomarker in diabetic macular edema.

To quantitatively analyze the number and density of macrophage-like cells (MLCs) at the vitreoretinal interface at macular region in diabetic retinopathy (DR) with and without diabetic macular edema (DME). This cross-sectional study involved 240 eyes of 146 treatment-naïve DR patients, including 151 eyes with DME. The number and density of MLCs were analyzed quantitatively using optical coherence tomography angiography (OCTA) and were compared between DME and non-DME eyes as well as proliferative DR (PDR) and non-PDR (NPDR) eyes. Correlation between MLCs density and vessel density of macular superficial capillary plexus (SCP) at macular region was evaluated. The number and density of macular MLCs were both elevated in DME group compared to non-DME group (all p < 0.001). The morphology of MLCs in DME eyes appeared larger and fuller. NPDR eyes had higher number and density of MLCs (p = 0.027 and 0.026), greater central macular thickness (CMT) (p = 0.002) and vessel density than PDR eyes in non-DME group but comparable to PDR eyes in DME group. The number and density of MLCs at macular region were significantly higher with larger and fuller morphology in DR patients with DME than those without DME. PDR eyes had fewer MLCs than NPDR eyes for DR eyes without DME.