An illustration of an in-vivo corneal response to a soft lens presoaked in a non-isotonic solution.

The use of hydrophilic gel contact lenses as a carrier of a non-isotonic saline solution provokes an irreversible increase in corneal thickness in the in-vivo rabbit eye. Studies on humans confirm the nature of the animal response, and it is therefore suggested that particular care should be taken when patients prepare saline solutions.