Glycosylation of the retina

Unlike the cornea and tear fluid, glycosylation within the retina remains remarkably underexplored. This review highlights the diverse roles of glycans in retinal development and vision, with a focus on major glycan classes, including glycosphingolipids (GSLs; glycans attached to lipids), N- and O-linked glycans on proteins, glycosaminoglycans (GAGs) on proteoglycans, O-mannosylated proteoglycans, and intracellular O-GlcNAcylation. Together, these components provide a comprehensive framework for understanding glycan-mediated processes in retinal biology. Current knowledge of the retinal glycosylation nanolandscape, primarily derived from lectin binding and anti-glycan antibody studies, is summarised. The review also examines the roles of altered glycosylation in immune regulation and retinal diseases such as retinitis pigmentosa, age-related macular degeneration and diabetic retinopathy. Finally, key gaps in knowledge and priority areas for future research are discussed. The retina remains understudied with regard to the complex patterns of glycosylation. Alterations of these patterns could represent consequences or be driving pathology, given the well-established roles of glycan patterns in development and homeostasis in other tissues.