Radioactive lysozyme deposition on rigid corneal lenses with or without use of a contact lens care solution.

PURPOSE: The purpose of this study was to investigate the quantity of radioactive lysozyme deposited on various rigid corneal lenses, and the impact of using a care solution containing a surfactant.

METHODS

Seven rigid corneal lens materials were investigated in this study. Lenses were soaked in an artificial tear solution (ATS), containing, among other components, radioactively labelled 125I-lysozyme, for 18 h at 37°C, followed by a soak for 6 h in saline. Alternatively, a one-step peroxide-based disinfection solution, which contains a poloxamer as a surfactant, was used in place of saline to determine the impact of use of a care solution on deposition. This process of soaking in the ATS followed by soaking in saline or the care solution was repeated for 30 cycles to simulate one month of lens wear. The amount of radioactive lysozyme remaining on the different lenses after 30 cycles was then quantified through gamma radiation counts.

RESULTS

Use of radioactively labelled 125I-lysozyme allowed for quantification of protein down to 0.19 μg/lens. Five of the seven contact lens materials tested showed a significant reduction in the amount of radioactive lysozyme remaining after using the care solution (range 1.33 ± 0.11-2.47 ± 0.13 μg/lens) compared to if only saline was used (range 1.25 ± 0.18-3.21 ± 0.66 μg/lens) after 30 simulated cycles.

CONCLUSIONS

The small amounts of lysozyme deposited on rigid contact lenses can be quantified using radioactively labelled 125I-lysozyme. Use of a care solution leads to lower amounts of lysozyme remaining on the lenses compared to saline, however, some lysozyme still remains and is not removed.