Original Article

Modulation Transfer Function of a Toric Intraocular Lens: Evaluation of the Changes Produced by Rotation and Tilt

Adelina Felipe, PhD; José M. Artigas, PhD; Amparo Díez-Ajenjo, PhD; Carmen García-Domene, MSc; Cristina Peris, MD, PhD

  • Journal of Refractive Surgery
  • May 2012 - Volume 28 · Issue 5: 335-340
  • DOI: 10.3928/1081597X-20120321-01
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Abstract

PURPOSE:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

AUTHORS

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

doi: 10.3928/1081597X-20120321-01

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