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Conditioning of hydrogel lenses by a multipurpose solution containing an ocular lubricant.

PURPOSE
The addition of the ocular lubricant hydroxypropyl methylcellulose (HPMC) to a multipurpose contact lens solution conditions the hydrogel lens surface. This investigation reports the clinical benefits to contact lens wearers and the improved physical properties of the solution with HPMC added.


METHODS
One-hundred forty-seven subjects wearing a variety of hydrogel lenses used a multipurpose solution with and without addition of HPMC and were assessed for product comfort and preference. In the laboratory, conditioning by HPMC was demonstrated in fluid coating, dynamic contact angle, uptake of fluid on hydrogel lenses, and release of HPMC from lenses after soaking.


RESULTS
Lens wearers reported the multipurpose solution with HPMC more comfortable, including measures relating to maintaining lens moisture over time. The multipurpose solution with HPMC produced a thicker and longer-lasting layer of fluid on hydrogel lenses and other plastics than other multipurpose solutions. HPMC was found to adsorb to both group 1 and 4 lens materials and release gradually, with detectable amounts releasing from the lens beyond 12 hours.


CONCLUSIONS
The conditioning properties of the multipurpose solution with HPMC produce improved wetting of lenses and enhanced lens wearing comfort. Binding of HPMC to the lens surface and subsequent time-release is the probable mechanism for these benefits.