The efficiency of contact lens care regimens on protein removal from hydrogel and silicone hydrogel lenses

Abstract

Purpose: To investigate the efficiency of lysozyme and albumin removal from silicone hydrogel and conventional contact lenses, using a polyhexamethylene biguanide multipurpose solution (MPS) in a soaking or rubbing/soaking application and a hydrogen peroxide system (H(2)O(2)).

Methods: Etafilcon A, lotrafilcon B and balafilcon A materials were incubated in protein solutions for up to 14 days. Lenses were either placed in radiolabeled protein to quantify the amount deposited or in fluorescent-conjugated protein to identify its location, using confocal laser scanning microscopy (CLSM). Lenses were either rinsed with PBS or soaked overnight in H(2)O(2) or MPS with and without lens rubbing.

Results: After 14 days lysozyme was highest on etafilcon A (2,200 mug) >balafilcon A (50 microg) >lotrafilcon B (9.7 microg) and albumin was highest on balafilcon A (1.9 microg) =lotrafilcon B (1.8 microg) >etafilcon A (0.2 microg). Lysozyme removal was greatest for balafilcon A >etafilcon A >lotrafilcon B, with etafilcon A showing the most change in protein distribution. Albumin removal was highest from etafilcon A >balafilcon A >lotrafilcon B. H(2)O(2) exhibited greater lysozyme removal from etafilcon A compared to both MPS procedures (p<0.001) but performed similarly for lotrafilcon B and balafilcon A lenses (p>0.62). Albumin removal was solely material specific, while all care regimens performed to a similar degree (p>0.69).

Conclusions: Protein removal efficiency for the regimens evaluated depended on the lens material and protein type. Overall, lens rubbing with MPS before soaking did not reduce the protein content on the lenses compared to nonrubbed lenses (p=0.89).

Figure 1

Schematic diagram for experimental procedures. Contact lenses were incubated in lysozyme (HEL) and albumin (BSA) solution, followed by overnight soaking in different care regimens and the two methods to locate and quantify the protein on the lens. In the figure, 125I indicates iodine¹²⁵; BSA indicates bovine serum albumin; CL indicates contact lens; CLSM designates confocal laser scanning microscope; Exp indicates Experiment; H₂O₂ indicates hydrogen peroxide; HEL designates hen egg lysozyme; LY designates lucifer yellow vinyl sulfone; and MPS indicates multipurpose solution.

Figure 2

Lysozyme and albumin distribution through etafilcon A. CLSM (confocal laser scanning microscopy) scans were analyzed to locate the fluorescent-conjugated protein on the front surface, within the bulk region, and on the back surface of etafilcon A after one and 14 days of incubation. Lenses were either rinsed in phosphate buffered saline (PBS), soaked overnight in hydrogen peroxide (H₂O₂) or soaked overnight in a multipurpose solution (MPS) with (MPS-RUB) or without (MPS-NO-RUB) manual lens rubbing. A, B: These panels show the results for HEL (hen egg lysozyme), C, D: These panels show the results for BSA (bovine serum albumin).

Figure 3

Lysozyme and albumin distribution through lotrafilcon B. CLSM (confocal laser scanning microscopy) scans were analyzed to locate the fluorescent-conjugated protein on the front surface, within the bulk region, and on the back surface of lotrafilcon B after one and 14 days of incubation. Lenses were either rinsed in phosphate buffered saline (PBS), soaked overnight in hydrogen peroxide (H₂O₂) or soaked overnight in a multipurpose solution (MPS) with (MPS-RUB) or without (MPS-NO-RUB) manual lens rubbing. A, B: These panels show the results for HEL (hen egg lysozyme), C, D: These panels show the results for BSA (bovine serum albumin).

Figure 4

Lysozyme and albumin distribution through balafilcon A. CLSM (confocal laser scanning microscopy) scans were analyzed to locate the fluorescent-conjugated protein on the front surface, within the bulk region, and on the back surface of balafilcon A after one and 14 days of incubation. Lenses were either rinsed in phosphate buffered saline (PBS), soaked overnight in hydrogen peroxide (H₂O₂) or soaked overnight in a multipurpose solution (MPS) with (MPS-RUB) or without (MPS-NO-RUB) manual lens rubbing. A, B: These panels show the results for HEL (hen egg lysozyme), C, D: These panels show the results for BSA (bovine serum albumin).