In vitro friction testing of contact lenses and human ocular tissues: Effect of proteoglycan 4 (PRG4)

• Friction was tested on silicone hydrogel contact lenses against human ocular tissue.
• The effect of the natural lubricant proteoglycan 4 (PRG4) was tested for lenses.
• Lenses with a covalently linked lubricant layer had the lowest friction.
• PRG4 reduced friction for SiHy lenses against human cornea and eyelid tissues.

Contact lens friction was recently shown to correlate with in vivo comfort, with lower friction lenses providing improved comfort. Proteoglycan 4 (PRG4) is a recently discovered ocular surface boundary lubricant. The objectives of this study were to measure the friction of commercially available silicone hydrogel (SiHy) contact lenses against human cornea and eyelid tissues, and evaluate the ability of PRG4 to lubricate, and adhere to, SiHy contact lenses. The in vitro friction test employed here effectively measured and distinguished the SiHy contact lens friction coefficients against human eyelid and cornea tissues, and PRG4 functioned as an effective boundary lubricant.