title: β-Thalassemia and ocular implications: a systematic review.
abstract: BACKGROUND
  Beta-thalassemia is a severe genetic blood disorder caused by a mutation in the gene encoding for the beta chains of hemoglobin. Individuals with beta-thalassemia major require regular lifelong Red Blood Cell transfusions to survive. Ocular involvement is quite common and may have serious implications.
  
  
  METHODS
  Extensive review of observational studies on beta-thalassemia, to determine the prevalence and spectrum of ocular abnormalities, by clinical examination and multimodal imaging, and to investigate risk factors for their development.
  
  
  RESULTS
  Frequency of ocular involvement differs among various studies (41.3-85 %, three studies). Ocular findings in beta-thalassemia may correlate to the disease itself, iron overload or the chelating agents used. Beta-thalassemia ocular manifestations include ocular surface disease, as demonstrated by tear function parameters (two studies). Lens opacities are present in 9.3-44 % (five studies). Lenticular opacities and RPE degeneration correlated positively with use of desferrioxamine and deferriprone respectively (two studies). Ocular fundus abnormalities characteristic of pseudoxanthoma elasticum (PXE), including peau d'orange, angioid streaks, pattern dystrophy-like changes, and optic disc drusen are a consistent finding in seven studies. Patients with PXE-like fundus changes were older than patients without these fundus changes (two studies). Age (two studies) and splenectomy (one study) had the strongest association with presence of PXE-like fundus changes. Increased retinal vascular tortuosity independently of the PXE-like fundus changes was found in 11-17.9 % (three studies), which was associated with aspartate amino transferase, hemoglobin and ferritin levels (two studies). Fundus autofluorescence and electrophysiological testing (ERG and EOG) may indicate initial stages or more widespread injury than is suggested by fundus examination (two studies).
  
  
  CONCLUSIONS
  Beta-thalassemia may present with various signs, both structural and functional. Pseudoxanthoma elasticum like fundus changes are a frequent finding in patients with b-thalassemia. These changes increase with duration or severity of the disease. Retinal vascular tortuosity may be an additional disease manifestation related to the severity and duration of anemia and independent of the PXE-like syndrome. Patients with long-standing disease need regular ophthalmic checkups because they are at risk of developing PXE-like fundus changes and potentially of subsequent choroidal neovascularization.
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Aliki
authors.initials: A
authors.lastname: Liaska
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Petros
authors.initials: P
authors.lastname: Petrou
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Constantinos D
authors.initials: CD
authors.lastname: Georgakopoulos
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Ramza
authors.initials: R
authors.lastname: Diamanti
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Papaconstantinou
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece.
authors.forename: Menelaos G
authors.initials: MG
authors.lastname: Kanakis
authors.affiliation: 1st Department of Ophthalmology, Athens University, Mesogeion 154, Athens, 11527, Greece. igeorgalas@yahoo.com.
authors.forename: Ilias
authors.initials: I
authors.lastname: Georgalas
mesh_terms: D002614:Chelating Agents / Q000009:adverse effects; D006801:Humans; D019190:Iron Overload / Q000150:complications; D064887:Observational Studies as Topic; D012164:Retinal Diseases / Q000209:etiology*; D014786:Vision Disorders / Q000209:etiology*; D017086:beta-Thalassemia / Q000150:complications*
chemical_list: D002614:Chelating Agents