The effects of hypotonic and hypertonic solutions on the fluid content of hydrophilic contact lenses.

Twenty healthy volunteers were fitted with a Bausch & Lomb plano O4 bandage contact lens (center thickness, 0.06 mm; water content, 38.6%) in one eye and a CooperVision therapeutic bandage Permalens (center thickness, 0.24 mm; water content, 70%) in the other eye. Ten received eyedrops every hour for six hours of a solution of 224 ml Osmol and the other ten received a solution of 670 ml Osmol. At the end of the examination period water loss was 21.05% and 20.36% in the Permalens group with the hypertonic and hypotonic solutions, respectively, and 8.86% and 10.74% in the Bausch & Lomb lens groups with the hypertonic and hypotonic solutions, respectively. These values were not significant when compared to those for five control patients (13.75% water loss for the Permalens and 7.28% for the Bausch & Lomb contact lens), suggesting that other factors may be more significant in controlling hydrogel contact lens dehydration.