Changes in corneal thickness under four different rigid gas permeable contact lenses for daily wear.

The relation between corneal thickness changes and the Dk value of rigid contact lenses was investigated in 42 patients who were fitted with contact lenses for the first time. These 42 patients were divided into 4 groups that were fitted with contact lenses of different Dk values. Corneal thickness in the open-eye state was measured (mid-afternoon) before contact lens fitting and after 6 weeks of daily contact lens wear. The changes in corneal thickness were not significantly different among the 4 contact lens materials (Dk values 8, 26, 54, and 92). We conclude that for daily wear use the lower Dk materials meet corneal requirements. However, there is a significant trend; the higher Dk values result in a thinner cornea. Causes for this phenomenon are discussed.