Ocular findings in patients with transfusion-dependent β-thalassemia in southern Iran

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Abstract

Background

Ocular involvement may occur via several mechanisms in patients with transfusion-dependent β-thalassemia (TDT) mainly chronic anemia, iron overload and iron chelator toxicity. We aimed to evaluate the frequency of abnormal ocular findings and their relationship with hematologic parameters in TDT patients.

Methods

In this cross-sectional study from January 2018 to January 2019, a total of 79 patients with TDT over the age of 18 who were on iron-chelation therapy (ICT) were consecutively investigated. All patients were registered at the Thalassemia Comprehensive Center affiliated with Shiraz University of Medical Sciences, Shiraz, Southern Iran. Complete ophthalmic examination was performed by an expert ophthalmologist. Clinical and hematologic parameters were collected from the patients´ medical records.

Results

The mean age ± standard deviation (SD) of the patients was 28.4 ± 5.6 years (range: 18–43). Twenty-four patients (30.4%) were male and 29 (36.7%) were splenectomized. The mean ± SD of the best-corrected visual acuity (VA) was 0.960 ± 0.086 decimal, (range: 0.6–1), 0.016 ± 0.046 logMar, (range: 0–0.2). The frequency of patients with VA > 0.1 logMar was 3 (3.8%). The mean intraocular pressure (IOP) was 14.88 ± 3.34 (6–25) mmHg. Fundus abnormalities were observed in 8 patients (10.1%), consisting of increased cup-disk ratio (3.8%), vessel tortuosity (2.5%), retinal pigment epithelium degeneration (2.5%), myelinated nerve fiber layer (1.3%), and internal limiting membrane wrinkling (1.3%). No significant association was observed between fundus abnormalities, VA, or IOP with hematologic parameters ( P > 0.05). TDT patients with diabetes mellitus had significantly higher IOP ( P = 0.010) but similar frequency of fundus abnormalities with non-diabetic patients ( P > 0.05).

Conclusions

The frequency of ocular abnormalities in our patients was lower than the previous reports. The frequency of fundus abnormalities were similar in diabetic and non-diabetic thalassemia patients indicating close monitoring and proper management of the disease and comorbidities in these patients.

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Most cited references 33

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Beta-thalassemia.

Deborah Rund, Eliezer Rachmilewitz (2005)

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Beta-thalassemia.

Antonio Cao, Renzo Galanello (2010)

Beta-thalassemia is caused by the reduced (beta) or absent (beta) synthesis of the beta globin chains of the hemoglobin tetramer. Three clinical and hematological conditions of increasing severity are recognized, i.e., the beta-thalassemia carrier state, thalassemia intermedia, and thalassemia major. The beta-thalassemia carrier state, which results from heterozygosity for beta-thalassemia, is clinically asymptomatic and is defined by specific hematological features. Thalassemia major is a severe transfusion-dependent anemia. Thalassemia intermedia comprehend a clinically and genotypically very heterogeneous group of thalassemia-like disorders, ranging in severity from the asymptomatic carrier state to the severe transfusion-dependent type. The clinical severity of beta-thalassemia is related to the extent of imbalance between the alpha and nonalpha globin chains. The beta globin (HBB) gene maps in the short arm of chromosome 11, in a region containing also the delta globin gene, the embryonic epsilon gene, the fetal A-gamma and G-gamma genes, and a pseudogene (psiB1). Beta-thalassemias are heterogeneous at the molecular level. More than 200 disease-causing mutations have been so far identified. The majority of mutations are single nucleotide substitutions, deletions, or insertions of oligonucleotides leading to frameshift. Rarely, beta-thalassemia results from gross gene deletion. In addition to the variation of the phenotype resulting from allelic heterogeneity at the beta globin locus, the phenotype of beta-thalassemia could also be modified by the action of genetic factors mapping outside the globin gene cluster and not influencing the fetal hemoglobin. Among these factors, the ones best delineated so far are those affecting bilirubin, iron, and bone metabolisms. Because of the high carrier rate for HBB mutations in certain populations and the availability of genetic counseling and prenatal diagnosis, population screening is ongoing in several at-risk populations in the Mediterranean. Population screening associated with genetic counseling was extremely useful by allowing couples at risk to make informed decision on their reproductive choices. Clinical management of thalassemia major consists in regular long-life red blood cell transfusions and iron chelation therapy to remove iron introduced in excess with transfusions. At present, the only definitive cure is bone marrow transplantation. Therapies under investigation are the induction of fetal hemoglobin with pharmacologic compounds and stem cell gene therapy.

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The molecular basis of β-thalassemia.

Swee Thein (2013)

The β-thalassemias are characterized by a quantitative deficiency of β-globin chains underlaid by a striking heterogeneity of molecular defects. Although most of the molecular lesions involve the structural β gene directly, some down-regulate the gene through distal cis effects, and rare trans-acting mutations have also been identified. Most β-thalassemias are inherited in a Mendelian recessive fashion but there is a subgroup of β-thalassemia alleles that behave as dominant negatives. Unraveling the molecular basis of β-thalassemia has provided a paradigm for understanding of much of human genetics.

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Author and article information

Contributors

Hossein Ashraf:

ORCID: http://orcid.org/0000-0003-4429-1658

hosseinashraf@yahoo.com

Journal

Journal ID (nlm-ta): BMC Ophthalmol

Journal ID (iso-abbrev): BMC Ophthalmol

Title: BMC Ophthalmology

Publisher: BioMed Central (London )

ISSN (Electronic): 1471-2415

Publication date (Electronic): 22 September 2020

Publication date PMC-release: 22 September 2020

Publication date Collection: 2020

Volume: 20

Electronic Location Identifier: 376

Affiliations

[1 ]GRID grid.412571.4, ISNI 0000 0000 8819 4698, Hematology Research Center, , Shiraz University of Medical Sciences, ; Shiraz, Iran

[2 ]GRID grid.412571.4, ISNI 0000 0000 8819 4698, Poostchi Ophthalmology Research Center, , Shiraz University of Medical Sciences, ; Shiraz, Iran

Author information

Hossein Ashraf http://orcid.org/0000-0003-4429-1658

Article

Publisher ID: 1647

DOI: 10.1186/s12886-020-01647-y

PMC ID: 7510146

PubMed ID: 32962679

SO-VID: 48e2733a-fc74-47f4-9fcf-eb0060289b39

License:

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

History

Date received : 31 March 2020

Date accepted : 17 September 2020

Funding

Funded by: Vice-Chancellor for Research, Shiraz University of Medical Sciences (IR)

Award ID: 11886

Award Recipient : Sezaneh Haghpanah

Custom metadata

ScienceOpen disciplines: Ophthalmology & Optometry

Keywords: β-thalassemia,iron-chelation therapy,iron overload,ocular manifestation,retinal abnormality

Data availability:

ScienceOpen disciplines: Ophthalmology & Optometry

Keywords: β-thalassemia, iron-chelation therapy, iron overload, ocular manifestation, retinal abnormality

Ocular findings in patients with transfusion-dependent β-thalassemia in southern Iran

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Most cited references 33

Beta-thalassemia.

Beta-thalassemia.

The molecular basis of β-thalassemia.

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