pH consistency and stability of contact lens solutions.

The pH of contact lens solutions has been implicated in the comfort of contact lenses on insertion. The pH of five samples each of 11 different products available for the rinsing and wetting of contact lenses was measured over a 4-month period. Buffered solutions were initially neutral to slightly basic (mean pH 7.03-7.83) and remained relatively close to their original pH throughout the study. The unbuffered solutions tested were initially acidic (5.81 and 5.46). One unbuffered solution rapidly became even more acidic (5.01) before rebounding slightly toward its original value. The difference in the mean pH between all the buffered solutions and the unbuffered solutions was found to be statistically significant. This study indicates the use of buffered solutions unless otherwise contraindicated.