RESUMO
We evaluated the pH of eight brands of aerosol saline solution to determine if there is a change in pH during the normal usage of an aerosol canister. The pH measurements were taken over a period of 14 to 24 days with a Corning model 10 pH meter (accuracy +/- 0.05 pH units). The saline was expelled and measured daily in 15-ml increments, the approximate volume used each day by soft lens wearers. We found no significant change in pH within each brand evaluated over the test period. However, there was a statistically significant difference in the median pH of the buffered and the unbuffered aerosol saline solutions. The mean pH of the buffered aerosol saline solutions, which averaged 7.30 pH units, was within the ocular comfort range. The mean pH of the unbuffered aerosol saline solutions, which averaged 5.79 pH units, was outside the ocular comfort range. This indicates that all aerosol saline solutions should be buffered.
