title: Refractive errors and ocular biometry components in thalassemia major patients.
abstract: The aim of this study is to determine and compare biometric and refractive characteristics of thalassemia major patients and normal individuals. In this cross-sectional study, 54 thalassemia major patients were selected randomly as case group, and 54 age- and sex-matched healthy subjects were regarded as control group. Refractive errors, corneal curvature and ocular components were measured by autokeratorefractometery and A-scan ultrasonography, respectively. Mean spherical equivalent was -0.0093 ± 0.86 D in thalassemia patients and -0.22 ± 1.33 D in the normal group. The prevalence of myopia, Hyperopia, and emmetropia among thalassemia patients was 16.7, 19.4, and 63.9 %, respectively. While in the control group, 26.9 % were myopic, 25 % were hyperopic, and 48.1 % were emmetropic. The prevalence of astigmatism in case group was 22.2 %, which was not significantly different from that in control group, (27.8 %, p = 0.346). Mean axial length in thalassemia patients was 22.89 ± 0.70 which was significantly lower than that in normal group (23.37 ± 0.91, p = 0.000). The flattest meridian of the cornea (R1) was significantly steeper in thalassemia patients (7.77 ± 0.24) in comparison to normal individuals (7.85 ± 0.28). Although thalassemic patients had significantly smaller axial length and vitreous chamber depth in comparison to normal group, which could be due to their abnormal physical growth, there was no significant difference between the mean of spherical equivalent among two groups. This can be due to their steeper corneal curvature that overcomes the refractive disadvantage of their shorter axial length.
authors.affiliation: Department of Optometry, School of Paramedical Science, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Heydarian
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. rezaj76@yahoo.com.
authors.forename: Reza
authors.initials: R
authors.lastname: Jafari
authors.affiliation: Thalassemia Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Hosein
authors.initials: H
authors.lastname: Karami
mesh_terms: D000293:Adolescent; D000328:Adult; D058452:Axial Length, Eye / Q000473:pathology; D001699:Biometry; D016022:Case-Control Studies; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology; D008297:Male; D012030:Refractive Errors / Q000453:epidemiology* / Q000209:etiology; D014822:Vitreous Body / Q000473:pathology; D055815:Young Adult; D017086:beta-Thalassemia / Q000473:pathology / Q000503:physiopathology*
keywords: Axial length; Corneal curvature; Ocular biometry; Refractive error; Thalassemia major