Comparative Tear Fluid Proteomics to Explore Treatment Responsiveness in Diabetic Macular Edema: A Pilot Study

Diabetic macular edema (DME) is a leading cause of vision loss in patients with diabetes, with variable responses to intravitreal antivascular endothelial growth factor (VEGF) therapy. This study aimed to identify tear fluid proteins linked to treatment responsiveness. Tear fluid samples were collected from 13 patients with diabetes (21 eyes with DME), among which 9 samples were analyzed using tandem mass tag-labeled liquid chromatography–mass spectrometry, and all 21 samples were validated with ELISA. Protein identification and quantification were performed using MaxQuant. Gene set enrichment analysis identified differentially expressed proteins, and an enzyme-linked immunosorbent assay was used to validate specific protein targets. Among the 3121 quantified proteins, DME-related proteins were enriched in cellular localization, oxidative stress response, and VEGFA-VEGFR2 signaling. Responders’ tear fluid proteomes were linked to modulation of the extracellular matrix and inflammation, whereas nonresponders showed enrichment in inflammation and NOTCH/WNT pathways. Targeted protein analysis demonstrated that the interplay between TIMP1, MMP9, and insulin growth factor binding protein 3 (IGFBP3) correlated with treatment response. These results suggest that tear fluid proteomic analysis is a promising alternative to intraocular sampling for evaluating DME responsiveness, offering insights consistent with aqueous and vitreous proteomes while aligning with clinical prognosis and disease pathophysiology.