AbstractA group of 15 subjects were fitted with truncated toric soft lenses varying in cylinder power from 1 to 4 D, in 1 D steps, with axes 90 and 180°. After 30 min of wear, the location of the truncation was measured from a slitlamp photograph and calculated from a spherocylindrical over-refraction. Blink-initiated rotation of the lenses was measured by slitlamp photography. Comparison of the location of the truncation of lenses with cylinder at axes 90 and 180° showed no significant difference using matched pair analysis, nor was cylinder power found to effect truncation location. However, analysis of the incidence of acceptable location (truncation within 25° of the horizontal) showed significantly more acceptable locations for those toric lenses with the cylinder at axis 90° (against-the-rule). A significant product moment correlation between the amount of mislocation of the axis and blink-initiated rotation was found. A high correlation was found between axis location measured from photographs and that calculated from over-refraction. However, because of the large variance of the differences between the two values, over-refraction is not considered to be a clinically acceptable method of determining toric lens axis location. The significance of the results of this study are discussed with respect to toric lens design.