Changes in anisometropia by age in children with hyperopia, myopia, and antimetropia

www.nature.com/scientificreports OPEN Changes in anisometropia by age in children with hyperopia, myopia, and antimetropia Han‑Wen Lin 1,2, Meng‑Ling Young 2,3, Christy Pu 4, Chung‑Ying Huang 2,3, Ken‑Kuo Lin 2,3, Jiahn‑Shing Lee 2,3 & Chiun‑Ho Hou 2,3,4,5* Anisometropia is a unique condition of both eyes and it is associated with vision problems such as amblyopia and reduced stereoacuity. Previous studies have not reported its change pattern by age and its correlation with the refractive condition of both eyes. This study aims to compare the changes in anisometropia by age in children with hyperopia, myopia, and antimetropia. In total, 156 children were included. Children aged 3–11 years with anisometropia ≥ 1.00 D were followed up for ≥ 1 year with ≥ 2 visits at two medical centers in Taiwan. Refractive errors by cycloplegic autorefractometry, best-corrected visual acuity, eye position, and atropine use were recorded. The children were divided into hyperopic, myopic, and antimetropic groups. The results showed that anisometropia decreased in children aged < 6 years (3.34–2.96 D; P = 0.038) and increased in older children (2.16–2.55 D; P = 0.005). In children aged 3, 4, 5, and 6 years, the mean anisometropia was higher in children with myopia and antimetropia than in those with hyperopia (P = 0.005, 0.002, 0.001, and 0.011, respectively). The differences were not significant in children aged > 6 years (all P > 0.05). The factors associated with changes in anisometropia were age, refractive group, amblyopia, and strabismus. Anisometropia decreased with age in children younger than 6 years, and the changes in anisometropia was found in children with myopia and antimetropia. Anisometropia is a unique condition in which the 2 eyes of an individual differ in refractive error by ≥ 1.0 D. Studies have reported its prevalence to range from 1.27 to 7% in different age and ethnic g roups1–4. Moreover, it is associated with vision problems, such as amblyopia and s tereoacuity5. Similar to the wide range of distribution of refraction in neonates, infantile anisometropia results from the stochastic combination of axial length and ocular refractive components in both eyes6. As children grow, some infantile anisometropia undergoes a change in magnitude through e mmetropization7, resulting in emmetropia or low hyperopia; the process is largely completed by the age of 6 years6. Therefore, age is a crucial factor that affects changes in anisometropia. Several studies have investigated the changes in anisometropia that occur with age in c hildren1,7–13; of these, some included children going through the emmetropization process. The prevalence of anisometropia decreased in a US-based cohort study, which measured the condition by using noncycloplegic retinoscopy1. In a Swedenbased study of 20 children, anisometropia decreased in the majority of the c hildren7. Two studies focused on children with m yopia12,13. Of these, the Egypt-based study reported that anisometropia increased until the age of 2 years and was followed by a nonsignificant decrease12; the Italy-based study reported that anisometropia decreased with age13. Another Taiwan-based study on amblyopic children demonstrated that anisometropia decreased in children with myopia but remained the same in children with hyperopia8. Although much research has been conducted on anisometropia, 2 gaps remain. First, the changes in anisometropia and its correlation with age remain unclear. Second, whether the different changes between refractive groups also occur in children without amblyopia remains unclear. Therefore, we investigated the changes in anisometropia in Taiwanese children in different refractive groups and ages, and identified the associated factors. 1 Department of Dermatology, Chang Gung Memorial Hospital, Linkou, Taiwan. 2Department of Medicine, School of Medicine, Chang Gung University, Taoyüan, Taiwan. 3Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan. 4Institute of Public Health, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan. 5Department of Ophthalmology, National Taiwan University Hospital, 7, Chung Shan S. Rd., Zhongzheng Dist., Taipei 100225, Taiwan (R.O.C.). *email: Scientific Reports | (2023) 13:13643 | https://doi.org/10.1038/s41598-023-40831-0 1 Vol.:(0123456789) www.nature.com/scientificreports/ Methods This retrospective study reviewed the medical charts of children with anisometropia presenting to the ophthalmology clinic at Linkou and Taipei Chang Gung Memorial Hospitals in Taiwan for consultant with 1 of 3 ophthalmologists (MLY, CYH, and CHH) between April 2018 and December 2018. Children aged 3–11 years and presenting for the first time were included. Anisometropia was defined as a spherical equivalent (SE) difference of ≥ 1.00 D, as suggested by previous s tudies1,9. To reveal a trend in changes in anisometropia, children who were followed up for at least a year with a minimum of 2 visits were included. We excluded children with organic ocular disorders, such as corneal opacity, congenital cataract, congenital malformation, or congenital glaucoma. The study was conducted in accordance with the tenets of the Declaration of Helsinki. The Institutional Review Board of Chang Gung Memorial Hospital in Linkou, Taiwan approved the study protocol (IRB number: 202001367B0), and the Institutional Review Board of Chang Gung Memorial Hospital in Linkou, Taiwan waived the requirement of written informed consent. The information on demographics, refractive error, strabismus, amblyopia, best corrected visual acuity, and atropine use (in one or both eyes for at least 1 year) was retrieved from medical records. The refractive errors were obtained using cycloplegic autokeratorefractometry (Topcon KR-800, Topcon Corporation, Tokyo, Japan). Cycloplegia was achieved by applying 1% tropicamide twice, 20 min and 30 min before examination, or by atropine of 0.125%, 0.25% or 0.5% if the child was a regular user with nightly administration. Children were divided into 3 refractive groups according to the refractive conditions of both eyes, namely the hyperopic (both eyes SE > 0.00 D), antimetropic (one eye SE ≥ 0.00 D; the other eye ≤ 0.00 D), and myopic (both eyes SE < 0.00 D) groups, on the basis of the refraction of both eyes, as assessed at the first visit. We documented children whose refractive error change in one or both eyes during the follow-up period led to a change in their refractive group for at least 2 years. Analysis of variance and chi-square tests were used to analyze differences in demographic characteristics for continuous and categorical variables, respectively. We used a paired t test to analyze the longitudinal changes in the SE difference. We also used analysis of variance (ANOVA) to perform an analysis of the between-group difference in the mean anisometropia among children in three refractive groups stratified by age, with the ages of the i (...truncated)