What is the purpose of fluorine in rigid oxygen permeable lenses?

Fluorine is used in rigid oxygen permeable lenses primarily to enhance wettability and improve deposit resistance. The incorporation of fluorine into the lens material modifies the surface properties.

When fluorine is added, it makes the surface more hydrophilic, which helps in attracting moisture, allowing for better tear film stability over the lens surface. This increased wettability is crucial for the comfort of the wearer, as it helps to reduce dryness and irritation that can sometimes occur with contact lenses.

Moreover, fluorine creates a surface that resists deposits from proteins, lipids, and other contaminants that may accumulate on the lens over time. By reducing the adhesion of these deposits, the lenses can maintain better clarity and comfort, extend their usable life, and require less frequent cleaning and maintenance. This overall enhancement in performance is why the correct choice emphasizes the combination of increased wettability and enhanced resistance to deposits.