Protein Deposition on a Lathe‐Cut Silicone Hydrogel Contact Lens Material

ABSTRACT Purpose. To determine the quantity of total protein, total lysozyme, and the conformational state of lysozyme deposited on a novel, lathe‐cut silicone hydrogel (SiHy) contact lens material (sifilcon A) after 3 months of wear. Methods. Twenty‐four subjects completed a prospective, bilateral, daily‐wear, 9‐month clinical evaluation in which the subjects were fitted with a novel, custom‐made, lathe‐cut SiHy lens material. The lenses were worn for three consecutive 3‐month periods, with lenses being replaced after each period of wear. After 3 months of wear, the lenses from the left eye were collected and assessed for protein analysis. The total protein deposited on the lenses was determined by a modified Bradford assay, total lysozyme using Western blotting and the lysozyme activity was determined using a modified micrococcal assay. Results. The total protein recovered from the custom‐made lenses was 5.3 ± 2.3 μg/lens and the total lysozyme was 2.4 ± 1.2 μg/lens. The denatured lysozyme found on the lenses was 1.9 ± 1.0 μg/lens and the percentage of lysozyme denatured was 80 ± 10%. Conclusions. Even after 3 months of wear, the quantity of protein and the conformational state of lysozyme deposited on these novel lens materials was very similar to that found on similar surface‐coated SiHy lenses after 2 to 4 weeks of wear. These results indicate that extended use of the sifilcon A material is not deleterious in terms of the quantity and quality of protein deposited on the lens.