Squeeze forces in contact lenses with a steep base curve radius.
Hydrodynamic forces occur on lenses due to pressures created in tear films during squeeze motions. Pressures and squeeze forces are calculated for lenses with both flat and steepened base curve radii. A parabolic two-dimensional tear film tickness is assumed for calculation purposes. A tear film with a peripheral film thickness of one-half of the central film thickness produces over three times the squeeze force produced by a constant tear film thickness with the same central clearance. Also, the distance moved by the lens toward the corneal surface is determined.
D003261:Contact Lenses / Q000592:standards*; D006801:Humans; D008433:Mathematics; D055585:Physical Phenomena; D010825:Physics; D011312:Pressure; D013314:Stress, Mechanical; D013666:Tears