Cytoprotective properties of carboxymethyl cellulose (CMC) when used prior to wearing contact lenses treated with cationic disinfecting agents.

PURPOSE: Disinfecting agents found in current multipurpose solutions (MPS) may produce low-grade ocular surface insults. This study investigates the potential for carboxymethylcellulose (CMC) to chemically complex residual disinfectants in situ.
METHODS: The chemical availability of the MPS disinfectant polyhexamethylene biguanide (PHMB) was examined using a spectrophotometric assay. PHMB bioactivity was assessed by survival of bacteria in the presence of MPS with varying amounts of added CMC.
RESULTS: Chemical availability of PHMB in water or MPS was reduced within 10 minutes of adding CMC. With the addition of CMC to MPS, survival rates for bacteria improved substantially, depending on the bacterial species, concentration, and exposure time.
CONCLUSIONS: Carboxymethylcellulose rapidly binds PHMB and reduces its chemical availability and bioactivity. These results suggest a potential cytoprotective effect of CMC on the ocular surface when used before lens insertion.