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.
*BSOptom, MSc, FAAO
§PhD, FCOptom, FAAO
Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Received June 13, 2008; accepted September 19, 2008.
Centre for Contact Lens Research; School of Optometry; University of Waterloo; 200 University Avenue West; Waterloo, Ontario N2L 3G1, Canada; e-mail: firstname.lastname@example.org