Contact lenses chlorhexidine

Chlorhexidine is also cationic like BKC and exhibits similar incompatibilities. It is not as stable as BKC to autoclaving and may irritate the eyes. It tends to be more favoured in Europe than in the United States, and is particularly used in contact lens products. Chlorobutanol and phenylethyl aclohol are also widely used in ophthalmic products. However, chlorobutanol will hydrolyse in solution, and autoclaving is not usually possible without loss of preservative activity. It is also volatile and may be lost through the walls of plastic containers. 

Use of preserved tear substitutes with contact lenses is a concern because the preservatives may bind to the lens polymer, prolonging ocular retention and exposure, which may result in toxic or hypersensitivity reactions. BAK is more readily absorbed than are thimerosal and chlorhexidine in most hydrogel lenses. 

Chlorhexidine diglnconate is a biguanide surfactant with low toxicity, bnt it is a strong contact sensitizer. Its mncns-binding capacity hmits its nse it binds to hydrophilic (soft) contact lenses. BnUd-up of proteinaceous debris in lenses may greatly increase the binding of chlorhexidine to the lens. 

Solutions formulated to clean hard gas-permeable contact lenses are sterile and pH buffered. They are soaking solutions and include lens-hydrating (wetting) agents (e.g., cationic cellulose derivatives) and preservatives (e.g., edetate disodium, chlorhexidine gluconate). 

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