pISSN: 1011-8942 eISSN: 2092-9382 Korean J Ophthalmol 2010;24(4):225-229 DOI: 10.3341/kjo.2010.24.4.225 Original Article Factors Influencing the Prevalence of Amblyopia in Children with Anisometropia Chong Eun Lee1, Young Chun Lee2, Se-Youp Lee1 1Department of Ophthalmology, Dongsan Medical Center, Keimyung University College of Medicine, Daegu, Korea 2Department of Ophthalmology, Uijongbu St. Mary’s Hospital, The Catholic University of Korea School of Medicine, Seoul, Korea Purpose: To evaluate factors that can influence the prevalence of amblyopia in children with anisometropia. Methods: We retrospectively reviewed the records of 63 children 2 to 13 years of age who had anisometropic am- blyopia with a difference in the refractive errors between the eyes of at least two diopters (D). The type of aniso- metropia (myopia, hyperopia, and astigmatism), degree of anisometropia (＜2-3 D, ＜3-4 D, or ＞4 D), best cor- rected visual acuity (BCVA) of the amblyopic eye at the time of initial examination, BCVA differences between sound and amblyopic eyes, whether or not occlusion therapy was performed, compliance with occlusion therapy, and the patient’s age when eyeglasses were first worn were investigated. Results: There was an increase in the risk of amblyopia with increased magnitude of anisometropia (p=0.021). The prevalence of amblyopia was higher in the BCVA ＜20/40 group and in patients with BCVA differences ＞4 lines between sound and amblyopic eyes (p=0.008 and p=0.045, respectively). There was no statistical relationship between the prevalence of amblyopia and the type of anisometropia or the age when eyeglasses were first worn. Poor compliance with occlusion therapy was less likely to achieve successful outcome (p=0.015). Conclusions: Eyes with poor initial visual acuities of ＜20/40, a high magnitude of anisometropia, and a ＞4 line dif- ference in the BCVA between sound and amblyopic eyes at the initial visit may require active treatment. Key Words: Amblyopia, Anisometropia, Prevalence Amblyopia is a disorder of the visual system that is charac- terized by a decrease in the best corrected visual acuity (BCVA) in an eye with no organic pathology [1]. Anisometropia is a well-known cause of amblyopia [2]. Unequal refractive error between the two eyes produces abnormal binocular in- teraction and/or visual deprivation. Patients with anisome- tropic amblyopia usually have no identifiable ocular defects and the visual acuity of the sound eye is normal, which makes it difficult to diagnose the symptoms, and thus early treat- ment is often delayed. Because improvement in visual acuity with amblyopia treatment depends on the age at which treat- ment begins, earlier detection of children with anisometropic Received: August 17, 2009 Accepted: May 10, 2010 Reprint requests to Se-Youp Lee, M.D. Department of Ophthalmology Keimyung University College of Medicine, #194 Dongsan-dong, Jung-gu, Daegu 700-712, Korea. Tel: 82-53-250-7720, Fax: 82-53-250-7705, E-mail: lsy3379@dsmc.or.kr * This article was presented in part at the 99th spring meeting (April 2008) of the Korean Ophthalmological Society in Daegu, Korea. ⓒ 2010 The Korean Ophthalmological Society This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses /by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. amblyopia is desired [3-6]. According to Weakley [7,8], there is an increased risk of amblyopia with myopic anisometropia ＞2 diopters (D), hy- peropic anisometropia ＞1 D, and astigmatic anisometropia ＞1.5 D. Hussein et al. [9], in a study of amblyopic children older than six years of age, found that the risk factors for ani- sometropic amblyopia treatment failure were age ＞6 years at the onset of treatment, the presence of astigmatism of ＞1.5 D in the amblyopic eye, poor compliance with treatment, and initial visual acuity in the amblyopic eye of ≤20/200. The aim of this study was to determine and analyze factors early in the course of treatment that influence the prevalence of amblyopia in children with anisometropia. Materials and Methods Between January 2000 and December 2007, we retro- spectively reviewed the records of 63 children 2 to 13 years of age who had anisometropia with a difference in the re- fractive power between the eyes of at least 2 D. Patients with at least six months of follow-up were included in the study. 225