A review of the last 10 years regarding protein and lipid deposition on soft contact lenses

PURPOSE: To synthesize recent evidence on protein and lipid deposition on soft contact lenses (CLs) and to clarify how material chemistry and surface properties influence biomolecule interactions. METHODS: A structured narrative review of studies published between 2015 and 2025 was conducted, and the review protocol was registered in the PROSPERO database (registration number: CRD420261333929). Electronic searches of PubMed, Web of Science, and Scopus identified in vitro, ex vivo, and in vivo investigations evaluating protein and/or lipid interactions with hydrogel and silicone hydrogel (SiHy) CL materials. Data were qualitatively synthesized according to material class, surface modification strategy, biomolecule type, localization, and reported functional outcomes. RESULTS: Fourteen studies met the inclusion criteria. Ionic, high-water content hydrogels consistently exhibited high protein uptake, predominantly through bulk absorption, while preserving enzymatic activity of key tear proteins such as lysozyme. In contrast, unmodified SiHy CLs showed lower total protein deposition but greater susceptibility to nonpolar lipid adsorption. Imaging-based analyses revealed that surface-localized lipid deposition had greater functional relevance than bulk lipid diffusion. Biomimetic surface-modified SiHy incorporating MPC or PMPC demonstrated marked resistance to surface-associated protein and lipid fouling. CONCLUSION: Protein and lipid deposition on soft CLs is primarily governed by material chemistry and surface design rather than deposition quantity alone. Surface-associated fouling, especially lipid adsorption, plays a central role in tear film instability, supporting a functional, material-dependent framework for evaluating and optimizing contact lens performance.