Power Effect on Toric Contact Lens Rotational Stability

Background: Eyecare practitioners currently fitting soft toric contact lenses are often
limited by the parameters available in their in-office fitting set. To properly fit spherocylindrical lenses outside of the trial lens set parameters, multiple office visits are often required because practitioners need to order trial lenses of various powers and axis. This is due to the complexity ofachieving rotational stability which can be influenced by many factors. The purpose of this study is to evaluate the effect oflens power on the rotation of blink stabilized contact lenses. Methods: Four Acuvue Oasys 1-Day for Astigmatism contact lenses ofdifferent spherical powers were assessed on the right eye of33 subjects. The four different lenses powers were the following: +4.00 -1.25 x 180, pl -1.25 x 180, -4.00 -1.25 x 180, and -8.00 -1.25 x 180. After the manufacturer's recommended settling time, each contact lens was evaluated for rotation, centration, coverage, and movement. Then each subject was instructed to look in all positions of gaze and rotation was measured again to determine rotational stability. Results: Ofall the lenses evaluated, 89% of the lenses were considered dispensable based on appropriate centration, coverage, and movement. Seventy-nine percent ofthe lenses exhibited excellent rotational stability offive or less degrees. Each lens power tended to rotate nasally, with no statistically significant difference between lenses. Conclusions: For practitioners, fitting a toric lens inside the trial lens set, ofpowers piano to -6.00D, can predict how a toric lens outside the trial lens set will react on the ocular surface.