Retinol-binding protein 3 in ophthalmology: current evidence, research progress, and future perspectives.

Retinol-binding protein 3 (RBP3) is a photoreceptor-derived glyco-lipoprotein that plays a central role in retinoid trafficking between photoreceptors and the retinal pigment epithelium. Beyond its canonical role in the visual cycle, emerging evidence suggests that RBP3 may participate in retinal metabolic regulation, neurovascular protection, inflammatory modulation, and disease-related immune responses. This review critically summarizes current evidence regarding RBP3 in diabetic retinopathy, retinal degeneration, pathological myopia, primary congenital glaucoma, and uveitis. Among these conditions, diabetic retinopathy has the most extensive evidence base, including clinical association studies, proteomic analyses, and preclinical intervention experiments. However, most clinical studies remain correlational, and RBP3-based therapeutic strategies have not yet been validated in human interventional trials. In other diseases, such as primary congenital glaucoma and uveitis, the current evidence is more limited and is largely derived from proteomics or animal models. Therefore, RBP3 should currently be regarded as a promising but incompletely validated biomarker and therapeutic candidate. Future studies should clarify disease-stage-specific roles, receptor-mediated mechanisms, safety profiles, and clinical utility through large-scale prospective and mechanistic studies.