Analysis of protein and mucin components deposited on hydrophilic contact lenses

Formation of deposits on hydrophilic soft contact lenses causes patient discomfort and decreased lens performance. HPLC and SDS‐polyacrylamide gel electrophoresis have been used to resolve, identify, and quantify the biological materials from lens deposits, using catalase as an internal standard. Within the limits of detection by silver staining methods (above 0.2 μg), all proteins found in lens deposits were also found in human tear fluid (lactoferrin, albumin, tear‐specific prealbumin, lysozyme, and an unidentified protein of Mr = 35,000); however, the proportions of proteins deposited on lenses differed markedly from those in tear fuid. Among individual patient lenses, the relative amounts of proteins in lens deposits also showed considerable variation. Specific staining of lenses and electrophoretic gels with Alcian Blue/Periodic Acid‐Schiff's reagent indicated the presence of mucin components (glycoproteins and muco‐polysaccharides) on heavily deposited lenses, but not on normal or lightly deposited lenses. Severity of lens deposits correlated positively with staining density by silver or AB/PAS on SDS‐PAGE gels. Mucin caused loss of electrophoretic resolution (smearing) and formation of elemental silver “mirrors” on silver stained SDS‐PAGE gels. This investigation provides (a) new quantitative micro‐methods for protein analysis with individual soft contact lenses, and (b) chemical evidence that much is a major component of heavy deposits on hydrophilic lenses. New lens cleaning methods should therefore include dissolution of mucin.