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BioMed Research International
Volume 2013 (2013), Article ID 124327, 6 pages
http://dx.doi.org/10.1155/2013/124327
Clinical Study

Effect of Pupil Size on Optical Quality Parameters in Astigmatic Eyes Using a Double-Pass Instrument

Department of Ophthalmology, University of Kitasato School of Medicine, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252-0374, Japan

Received 17 April 2013; Revised 29 May 2013; Accepted 12 June 2013

Academic Editor: David Maintz

Copyright © 2013 Hidenaga Kobashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose. To objectively determine the effects of pupil size on optical quality parameters in astigmatic eyes using a double-pass instrument. Methods. We examined twenty-two eyes of 22 healthy volunteers (mean age ± standard deviation, years) who had no ophthalmic diseases other than refractive errors (manifest cylinder ≤0.25 diopters (D)). After we fully corrected cycloplegic refraction, we created with-the-rule astigma tism of 1, 2, and 3 diopters in these eyes and then quantitatively assessed the modulation transfer function (MTF) cutoff frequency and the Strehl2D ratio with 2-, 4-, and 6-mm pupil sizes using the Optical Quality Analysis System. Results. The MTF cutoff frequency and the Strehl2D ratio decreased significantly as the amount of astigmatism increased at each pupil size ( for 2, 4, and 6 mm, analysis of variance). They also decreased significantly with an increase in pupil size at each diopter of astigmatism ( for 0, 1, 2, and 3 D). Multiple comparisons demonstrated a significant difference between measurements made for a 2-mm pupil and for a 6-mm pupil at each diopter of astigmatism ( for 0, 1, 2, and 3 D, Dunnett test) and those made for a 4-mm pupil and for a 6-mm pupil at each diopter of astigmatism ( for 0 D, 1, 2, and 3 D). Conclusions. Eyes with larger pupils had lower optical quality even when they were astigmatic. It may be necessary to correct the preexisting astigmatism to acquire excellent visual performance, especially in astigmatic eyes with larger pupils.