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July2007 Vol.44 Issue:        2        Table of Contents
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Visual Function Evaluation of Egyptian Beta-Thalassemia Major Patients on Long-Term Desferal Therapy

Ann A. Abdel Kader1, Mona H. Abou El-Ela2, Sahar Abd Al-Atty3, Hossam Al-Din Khalil4, Mona Mohamed Nada1

Departments of Clinical Neurophysiology1, Pediatric2, Chemical Pathology3, Cairo University; Ophthalmology4, Beni Suef University



The success of the iron chelator desferal (DFO) in the treatment of beta - thalassemia is limited by its lack of bioavailability. Also, high dosage has been associated with toxicity of the eyes, ears and others. To investigate a possible subclinical visual neurotoxicity, 30 Egyptian p-thalassemia major (BTM) patients on long-term, recommended DFO dosage were studied using visual evoked potentials (VEPs) and electroretinogram (ERG). We also aimed to clarify the relation of the possible abnormalities to various clinical, hematologic and biochemical parameters. Ten healthy age - matched individuals were enrolled as controls. Sixteen/30 (53.3%) patients showed subclinical abnormalities using VEP and/or ERG. Nine/30 (30%) had VEPs abnormalities, 10 (33.3%) had ERG abnormalities and 3 (10%) revealed abnormalities by both methods. An interesting observation was the significant association of abnormal VEP and sex (P=0.0002). No significant correlation was found between neurophysiologic abnormalities and all data studied as: age, frequency of blood transfusion, DFO dosage/ duration, splenectomy, CBC values; S. ferritin, Serum Copper, S. Zinc and S. vitamin E. A single patient could have subclinical DFO-induced visual toxicity using VEP as his "toxicity" index (TI) was high (0.078). conclusion: the abnormalities can not be mostly attributed to long-term DFO therapy. Serial visual monitoring (including VEP and ERG) of all BTM patients is warranted. It is worthwhile to compare the long-term toxicity of the oral chelating agents (e.g. L 1 & ICL670) with that of DFO before definite conclusions are drawn on any visual neurotoxicity and its relation with the disease state or drug therapy.

(Egypt J. Neurol. Psychiat. Neurosurg., 2007, 44(2): 683-692)


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