Purpose. To evaluate the presence of hyperreflective spots (HRS) in diabetic patients without clinically detectable retinopathy (no DR) or with nonproliferative mild to moderate retinopathy (DR) without macular edema, and compare the results to controls. Methods. 36 subjects were enrolled: 12 with no DR, 12 with DR, and 12 normal subjects who served as controls. All studied subjects underwent full ophthalmologic examination and spectral domain optical coherence tomography (SD-OCT). SD-OCT images were analyzed to measure and localize HRS. Each image was analyzed by two independent, masked examiners. Results. The number of HRS was significantly higher in both diabetics without and with retinopathy versus controls (P < 0.05) and in diabetics with retinopathy versus diabetics without retinopathy (P < 0.05). The HRS were mainly located in the inner retina layers (inner limiting membrane, ganglion cell layer, and inner nuclear layer). The intraobserver and interobserver agreement was almost perfect (κ > 0.9). Conclusions. SD-OCT hyperreflective spots are present in diabetic eyes even when clinical retinopathy is undetectable. Their number increases with progressing retinopathy. Initially, HRS are mainly located in the inner retina, where the resident microglia is present. With progressing retinopathy, HRS reach the outer retinal layer. HRS may represent a surrogate of microglial activation in diabetic retina.

Higher number of HRS, larger area of IFAF and presence of SND may indicate a prevalent inflammatory condition in DME with specific response to targeted treatment.

These data may improve characterization of DME in eyes with SND. DME with SND correlates with greater CT, more HRS, disruption of the ELM, and significant macular functional impairment (RS decrease) vs SND-.

A significant decrease in HRS in the retina after anti-vascular endothelial growth factor treatment is documented. A decrease in HRS correlates with functional parameters, specifically RS. New parameters may be used for treatment evaluation in center-involving diabetic macular edema.

Glial fibrillary acidic protein, AQP1, and AQP4-biomarkers of Müller cell activity-are significantly increased in human eyes with diabetes, confirming that Müller cells are precociously affected by diabetes mellitus.

ABSTRACT.Purpose: Retinal glia cells (RGC) activation and release of inflammatory cytokines have been associated with development of diabetic retinopathy (DR). In this study, we evaluated by protein array the presence of aqueous humour (AH) cytokines secreted by RGC in patients with diabetes without DR and with mild DR. Methods: This is a cross-sectional, case-control study. Thirty-five subjects (diabetics and controls) underwent full ophthalmic examination and AH samples collection before cataract surgery at the Department of Ophthalmology University of Padova. AH samples were analysed for total protein concentration (Bradford method) and RGC-related inflammatory cytokines using glass chip protein arrays. Results: Twelve diabetic patients without DR, 11 diabetic patients with mild DR and 12 non-diabetic controls were included. There was no significant difference in total protein concentration among the 3 groups. Interleukin IL-1b, IL-3, interferon gamma (IFN-ɣ), (IFN-ɣ)-induced protein (IP)-10 and monocyte chemotactic protein (MCP)-2 were significantly increased in diabetics versus controls. IFN-ɣ, IL-1a, IL-3 and MCP-2 were significantly increased in diabetics without DR versus controls, whereas granulocyte-macrophage colonystimulating factor (GM-CSF), IFN-ɣ, IL-10, IP-10, regulated and normal T cell expressed and secreted (RANTES), and soluble tumour necrosis factor receptor (sTNF-R)II were significantly increased in diabetics with mild DR versus controls. Macrophage inflammatory protein (MIP-1b), GMCSF, RANTES and sTNF-RII were significantly increased in diabetics with mild DR versus diabetics without DR (p < 0.05 at least for all). Conclusions: Differences in expression profile of AH cytokines between diabetics, without and with mild DR, and controls have been documented. Retinal neuroinflammatory biomarkers of RGC activation evaluated in AH by protein array analysis could guide in detecting specific phenotypes with potential for personalized management.

Purpose: To evaluate the changes in activity of biomarkers of Müller cells (MC) in aqueous humor of patients with diabetic macular edema after subthreshold micropulse laser, over 1 year. Methods: Patients with untreated diabetic macular edema and central retinal thickness ≤ 400 μm were enrolled. Best-corrected visual acuity, full ophthalmic examination, and optical coherence tomography were performed. Subthreshold micropulse laser was applied every 3 months. Glial fibrillary acidic protein and inwardly rectifying potassium channel (Kir 4.1), MC activity markers, and vascular endothelial growth factor were quantified in the aqueous humor collected at baseline and at 1, 3, and 12 months after laser. Changes in the macular thickness and inner nuclear layer thickness, where MC bodies are located, were measured. Results: Ten eyes of 10 patients were included. Best-corrected visual acuity improved at 3 months (P = 0.047) and remained stable. Inner nuclear layer thickness significantly reduced at 12 months (P = 0.012). Glial fibrillary acidic protein, Kir 4.1, and vascular endothelial growth factor decreased at 1 and/or 3 and/or 12 months compared with baseline (P < 0.05). Conclusion: Subthreshold micropulse laser improves visual function in diabetic macular edema. Kir 4.1 and glial fibrillary acidic protein decrease and inner nuclear layer thickness reduction demonstrate that subthreshold micropulse laser may restore MC function. Subthreshold micropulse laser also reduces vascular endothelial growth factor concentration. The effect of subthreshold micropulse laser in diabetic macular edema may in part be due to changes of MC metabolic activity.

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