A comparison of three methods of measurement of toric soft lens orientation.

A group of five subjects were fitted with truncated toric soft lenses varying in minus cylinder power from 1 to 4 D in 1 D steps at axes of 90 and 180. After 15 min of lens wear, the location of the lens was measured by three techniques: the projected slitlamp photographic technique, measurement with a protractor graticule in the slitlamp eyepiece, and alignment of the slitlamp beam with markings on the lens. Analysis of the data by a four-level analysis of variance and a t-test showed no significant difference between the three methods of measuring the toric soft lens orientation.