The Effect of Contact Lens Thickness and Diameter on Residual Astigmatism

The flexure of contact lenses of various thicknesses and diameters and the associated residual astigmatism were measured on two spherical and two toric corneas. No significant results were found on the spherical corneas. On the toric corneas, no differences were found for lenses of various diameters, but differences were found for various lens thicknesses. While no significant flexure of change in residual astigmatism was found for lenses thicker than 0.12 mm. an average flexure of + 0.52 DC × 180 ±0.20 DC and associated residual astigmatism of −0.35 DC × 180 ±0.15 DC were found for lenses thinner than 0.12 mm. The study indicates that contact lens thickness can be varied to modify residual astigmatism.