A general relation between changing surface radii of flexing soft contact lenses.

Many models have been proposed to describe the simultaneous changes which occur in front and back radii of curvature of a hydrogel contact lens flexing or "wrapping" onto the surface of a human eye. This study first discusses the concept that the change in front radius (delta r1) may be related to the change in back radius (delta r2) by a simple constant which may change with lens design, and then develops a separate new general relation from observed lens behavior: delta r1/delta r2 = 1 - 0.05 F, where F is unflexed lens back vertex power.