Prevalence of anisometropia and its associated factors in school-age children

Hassan Hashemi; Mehdi Khabazkhoob; Carla Lança; Mohammad Hassan Emamian; Akbar Fotouhi

doi:10.1080/09273972.2023.2293883

Prevalence of anisometropia and its associated factors in school-age children

Strabismus. 2024 Jan 17:1-10. doi: 10.1080/09273972.2023.2293883. Online ahead of print.

Authors

Hassan Hashemi¹, Mehdi Khabazkhoob², Carla Lança^{3

4}, Mohammad Hassan Emamian⁵, Akbar Fotouhi⁶

Affiliations

¹ Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
² Department of Basic Sciences, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
³ Escola Superior de Tecnologia da Saúde de Lisboa (ESTeSL), Instituto Politécnico de Lisboa, Lisboa, Portugal.
⁴ Comprehensive Health Research Center (CHRC), Escola Nacional de Saúde Pública, Universidade Nova de Lisboa, Lisboa, Portugal.
⁵ Ophthalmic Epidemiology Research Center, Shahroud University of Medical Sciences, Shahroud, Iran.
⁶ Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.

PMID: 38230509
DOI: 10.1080/09273972.2023.2293883

Abstract

Purpose: To determine the prevalence of anisometropia and the associated demographic and biometric risk factors in children.

Methods: This cross-sectional study was conducted on the elementary school children of Shahroud, east of Iran, in 2015. All rural students were recruited, while multistage cluster sampling was used to select the students in urban areas. All children underwent optometric examinations including the measurement of uncorrected and corrected visual acuity, autorefraction, and subjective refraction with cycloplegia. Biometric components were measured using the Allegro Biograph. Myopia and hyperopia were defined as a spherical equivalent ≤-0.5 and ≥ +2.00 diopter, respectively. Students with a history of ocular trauma or lack of cycloplegic refraction at least in one eye were excluded from the study.

Results: Of 6624 selected children, 5620 participated in the study. After applying the exclusion criteria, the data of 5357 students (boys: 52.8%, n = 2834) were analyzed. The mean age of the subjects was 9.2 ± 1.7 years (range: 6-12 years). The prevalence of anisometropia ≥ 1 D was 1.1% (95% CI: 0.8 to 1.4) in all children, 1.0% (95% CI: 0.7-1.3) in boys, 1.3% (95% CI: 0.8-1.7) in girls, 1.1% (95% CI: 0.8-1.4) in urban children, and 1.4% (95% CI: 0.5-2.3) in rural children. The prevalence of anisometropia was 8.8% (95% CI: 5.3-12.2) in myopic and 5.7% (95% CI: 2.8-8.5) in hyperopic children. Axial length asymmetry (OR = 40.9; 95%CI: 10.2-164.1), myopia (OR = 17.9; 95% CI: 9.4-33.9), and hyperopia (OR = 10.1; 95% CI: (5.1-19.7) were associated with anisometropia in multiple logistic regression model. More anisometropia was associated with more severe amblyopia. The odds of amblyopia (OR = 82.3: 38.2-177-3) and strabismus (OR = 17.6: 5.5-56.4) were significantly higher in anisometropic children. The prevalence of amblyopia was 21.7% in children with myopic anisometropia ≥ 3D, 66.7% in children with hyperopic anisometropia ≥ 3D, and 100% in cases with antimetropia ≥ 3D.

Conclusion: The prevalence of anisometropia was low in Iranian school children. However, a high percentage of anisometropic students had amblyopia and strabismus. Axial length was the most important biometric component associated with anisometropia.

Keywords: Anisometropia; Iran; axial length; children; myopia.