Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 59 10 2021 11 10 603 609 Leili Koochakzadeh Department of Pediatrics, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Hassan Hashemi Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran Reza Pakzad Department of Epidemiology, Faculty of Health, Ilam University of Medical Sciences, Ilam, Iran Zahra Hemmatian Rabbani Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran Samira Heydarian Department of Rehabilitation Sciences, School of Allied Medical Sciences, Mazandaran University of Medical Sciences, Sari, Iran 6 Department of Pediatrics, Dezful University of Medical Sciences, Dezful, Iran Abbasali Yekta Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran Fahimeh Khoshhal Department of Pediatrics, Dezful University of Medical Sciences, Dezful, Iran Hadi Ostadimoghaddam Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Parastoo Tajzadeh Higher Health Education, Complex of Kashmar, Mashhad University of Medical Sciences, Mashhad, Iran Sara Sardari Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran Mehdi Khabazkhoob Department of Medical-Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2020 10 26 2021 08 09 To determine and compare ocular characteristics and refractive errors between major thalassemia patients and normal subjects. In this study, 71 thalassemia major patients and 79 age and sex-matched healthy subjects that were selected in an ongoing manner underwent complete optometric and ophthalmic examinations, including autorefraction, subjective refraction, fluorescein tear break-up time, and pachymetry after anthropometric measurements. The results showed that the mean UCVA was better in the control group versus the thalassemia group (P<0.001), while there was no difference in BCVA between the two groups (P=0.416). Moreover, the mean spherical equivalent was 0.38±0.13 D less in the thalassemia group compared to the control group (P=0.007), while corneal power (P<0.001) and cylinder power (P=0.001) were larger in thalassemia patients. The most common type of astigmatism was against the rule pattern in thalassemia patients and with the rule pattern in the control group (P<0.001). The mean tear break-up time was 11.35±6.43 in the thalassemia group and 14.63±5.79 in the control group (P=0.001), and the mean near the point of accommodation (NPA) (P=0.009) and near the point of convergence (NPC). (P=0.003) were significantly smaller in the thalassemia group compared to the control group. These patients suffer from a myopic shift due to exaggerated responses to changes in ocular growth, dry eye secondary to goblet cell loss, and a higher prevalence of vertical astigmatism due to eyelid laxity and pressure on the cornea. Therefore, regular ophthalmological evaluations are highly recommended in these patients. https://acta.tums.ac.ir/index.php/acta/article/view/8898