- Journal of Refractive Surgery
- May 2012 - Volume 28 · Issue 5: 335-340
To evaluate the changes in optical quality when toric intraocular lenses (IOL) are rotated or tilted and to demonstrate that IOL rotation produces an increasing effect of aberrations.
Modulation transfer function (MTF) and average modulation were used to analyze the image quality of a toric IOL. The axis of the toric IOL was rotated 5°, 10°, 15°, 20°, 25°, and 30° in successive MTF measurements. The tilt values were 0° to 5°, in increments of 1°, plus a tilt of 15°. Pupil diameters of 3 and 5 mm were used.
The MTF decay due to aberrations was more sensitive to rotation than tilt. The main decrement in the average modulation, of approximately 50% in both pupils, occurs when the IOL rotates from 0° to 5°. Between 0° and 1° tilt, the average modulation decreases approximately 25% for both pupils; with tilt >1°, the average modulation remains virtually unchanged. The points representing average modulation versus rotation angle are satisfactorily fitted by an exponential function, R=0.98. Average modulation versus tilt angle provides lower correlation degrees, R=0.91 and R=0.79, for 3- and 5-mm pupils, respectively.
The MTF of the toric IOL decays with rotation and tilt, with greater decrement occurring in rotation from 0° to 5°. An asymptotic value exists in the average modulation decay, meaning that for angles higher than 15°, the average modulation of the toric IOL remains virtually constant.
From Fundación Oftalmológica del Mediterráneo (Felipe, Artigas, Díez-Ajenjo, García-Domene, Peris) and Departamento de Óptica, Facultad de Física, Universidad de Valencia (Felipe, Artigas, Díez-Ajenjo), Valencia, Spain.
Carmen García-Domene received grant support from Cátedra Alcon-Universitat de València, Spain.
The authors have no proprietary interest in the materials presented herein.
Correspondence: Adelina Felipe, PhD, Facultad de Física, Universidad de Valencia, C/Dr Moliner 50, E46100 – Burjassot (Valencia), Spain. Tel: 34 963544092; Fax: 34 963544715; E-mail: Adelina.Felipe@uv.es
Received: December 26, 2011
Accepted: February 21, 2012
Posted Online: March 26, 2012