Tear pumping and edema with soft contact lenses.

The effect of the contact lens--cornea bearing relationship on tear pumping and corneal swelling (edema) which accompanies hydrogel lens wear was determined by monitoring corneal thickness and tear replenishment rates when the base curve (back surface curvature) was varied from 7.8 to 9.0 mm. The lens movement is dependent on the bearing relationship; however, the degree of corneal swelling and the replenishment rate of tears under the lens are independent of the bearing relationship. These results indicate that the corneal edema which accompanies gel lens wear cannot be reduced by altering the lens-cornea bearing relationship.