The spectrum of ocular alterations in patients with β-thalassemia syndromes suggests a pathology similar to pseudoxanthoma elasticum

Angioid Streaks Remain a Challenge in Diagnosis, Management, and Treatment

Aim: Angioid streaks (ASs) are a rare retinal condition and compromise visual acuity when complicated with choroidal neovascularization (CNV). They represent crack-like dehiscences at the level of the Bruch's membrane. This objective narrative review aims to provide an overview of pathophysiology, current treatment modalities, and future perspectives on this condition. Materials and Methods: A literature search was performed using "PubMed", "Web of Science", "Scopus", "ScienceDirect", "Google Scholar", "medRxiv", and "bioRxiv." Results: ASs may be idiopathic, but they are also associated with systemic conditions, such as pseudoxanthoma elasticum, hereditary hemoglobinopathies, or Paget's disease. Currently, the main treatment is the use of anti-vascular endothelial growth factors (anti-VEGF) to treat secondary CNV, which is the major complication observed in this condition. If CNV is detected and treated promptly, patients with ASs have a good chance of maintaining functional vision. Other treatment modalities have been tried but have shown limited benefit and, therefore, have not managed to be more widely accepted. Conclusion: In summary, although there is no definitive cure yet, the use of anti-VEGF treatment for secondary CNV has provided the opportunity to maintain functional vision in individuals with AS, provided that CNV is detected and treated early.

Unusual presentation of tractional retinal detachment in beta thalassemia minor

Purpose

To report a case of proliferative retinopathy with tractional retinal detachment associated with beta thalassemia minor in a 27-year-old female.

Observations

A young lady having beta thalassemia minor presented with decreased vision in both eyes, the effect being more severe in her right eye. The patient's other systemic history, including ophthalmic history, was unremarkable. The fundus examination revealed peripheral retinal ischemia in both eyes and tractional retinal detachment in the right eye.

Conclusion

Beta thalassemia minor is not associated with striking retinal pathology, nevertheless proliferative retinopathy. However, in this case the patient developed tractional retinal detachment that required surgery. This indicates that proliferative changes may develop in patients with beta thalassemia, and routine fundus examinations could be recommended for these patients.

Burden of ocular abnormalities in patients with beta thalassaemia: a cross-sectional study

INTRODUCTION

In Pakistan, the reported carrier rate of thalassaemia is estimated to be 5%-8% with 5000 new patients diagnosed every year. Several known systemic complications of beta thalassaemia major have been studied, but no studies are conducted to assess ocular complications among these patients from our population.

METHODS

It was a cross-sectional study design conducted at three private and public sector centres in Pakistan. We recruited 203, 11-17 years old children with beta thalassaemia major in our study. Frequency of overall ocular complications such as retinal pigment epithelium degeneration, visual field defects, increased retinal vascular tortuosity, lenticular opacities, anterior segment abnormality, etc among beta thalassaemia patients were verified by an ophthalmologist.

RESULTS

On univariate analysis male gender (prevalence ratio (PR): 1.023 (0.903 to 1.160), OGTT levels (PR: 0.99 (0.978 to 1.003) and serum calcium levels (PR: 0.716 (0.616 to 0.936)) were significantly associated with ocular complications. However, on multivariable analysis after adjusting for covariates we observed that the prevalence of ocular complications was 88% higher in males as compared with females. Moreover, with every one unit increase in serum calcium levels the prevalence of ocular complications were decreased by 24%.

CONCLUSION

Our study results showed that the frequency of ocular complications in beta thalassaemia children was 22.7%. Male gender was a risk factor for ocular complications among children with beta thalassaemia. However, high calcium levels among these patients were found to be protective for ocular complications.

Mitochondrial Dysfunction and Oxidative Stress in Hereditary Ectopic Calcification Diseases

Ectopic calcification (EC) is characterized by an abnormal deposition of calcium phosphate crystals in soft tissues such as blood vessels, skin, and brain parenchyma. EC contributes to significant morbidity and mortality and is considered a major health problem for which no effective treatments currently exist. In recent years, growing emphasis has been placed on the role of mitochondrial dysfunction and oxidative stress in the pathogenesis of EC. Impaired mitochondrial respiration and increased levels of reactive oxygen species can be directly linked to key molecular pathways involved in EC such as adenosine triphosphate homeostasis, DNA damage signaling, and apoptosis. While EC is mainly encountered in common diseases such as diabetes mellitus and chronic kidney disease, studies in rare hereditary EC disorders such as pseudoxanthoma elasticum or Hutchinson-Gilford progeria syndrome have been instrumental in identifying the precise etiopathogenetic mechanisms leading to EC. In this narrative review, we describe the current state of the art regarding the role of mitochondrial dysfunction and oxidative stress in hereditary EC diseases. In-depth knowledge of aberrant mitochondrial metabolism and its local and systemic consequences will benefit the research into novel therapies for both rare and common EC disorders.

PATTERN DYSTROPHY-LIKE CHANGES ASSOCIATED WITH A VERY HIGH SERUM FERRITIN LEVEL IN β-THALASSEMIA MAJOR

PURPOSE

To report a rare case of pattern dystrophy-like retinal changes in a young β-thalassemia major patient with a very high serum ferritin level.

METHODS

Observational case report of a β-thalassemia major patient with bilateral pattern dystrophy-like retinal changes.

RESULTS

An 18-year-old man experienced blurring of vision in both eyes. Patient had a very high serum ferritin level and had a history of using various iron-chelating drugs. Funduscopy revealed bilateral widespread retinal pigment epithelium changes with macular involvement, which resembled pattern dystrophy-like changes. Fundus autofluorescence imaging showed extensive area of decreased autofluorescence signal interspersed with increased autofluorescence signals, whereas optical coherence tomography demonstrated macular retinal pigment epithelium thinning and interdigitation zone disruption corresponding to retinal pigment epithelium damage and atrophy.

CONCLUSION

Pattern dystrophy-like changes should be considered as a possible manifestation of retinal changes in patients with β-thalassemia major. Iron overload, which is indicated by a very high serum ferritin level, might have a role in the formation of this rare retinal manifestation in β-thalassemia major.

Optical coherence tomography findings in patients with transfusion-dependent β-thalassemia

BACKGROUND

Structural ophthalmologic findings have been reported in patients with β-thalassemia due to chronic anemia, iron overload, and iron chelation therapy toxicity in few previous studies. We aimed to investigate structural ocular findings and their relationship with hematological parameters in patients with transfusion-dependent β-thalassemia (TDT).

METHODS

In this cross-sectional study, from January 2018 to January 2019, 39 patients with TDT over the age of 18 participated. Multicolor fundus imaging, optical coherence tomography (OCT), and blue light fundus autofluorescence imaging were performed for all patients and 27 age- and sex-matched controls.

RESULTS

The mean age of patients was 28.6 ± 6.2 years. The central macular thickness and macular thicknesses in all quadrants were significantly thinner in patients than controls (P<0.05). None of the retinal nerve fiber layer (RNFL) measurements were significantly different between TDT patients and controls. There was a significantly negative correlation between hemoglobin with central macula thickness (r=-0.439, P=0.005). All measurements of macular subfield thickness were insignificantly thinner in patients with diabetes mellitus (DM) compared to the non-DM subgroup.

CONCLUSIONS

Macular thickness was significantly thinner in central macula and entire quadrants in TDT patients compared to healthy individuals; however, all RNFL measurement thicknesses were comparable between the two groups. Close monitoring of TDT patients by periodic ophthalmologic examinations with more focus on diabetic patients, patients with severe anemia and iron overload should be warranted.

Novel retinal findings in β-thalassemia major: older age and higher ferritin level as the risk factors

PURPOSE

To investigate retinal changes in β-thalassemia major patients and identify their association with systemic risk factors.

METHODS

In this prospective study, 120 β-thalassemia major patients received complete ophthalmic examinations (best-corrected visual acuity, contrast sensitivity, color vision, and indirect ophthalmoscopy) and retinal imaging using color fundus photography and fundus autofluorescence imaging. Patients were grouped according to the presence of thalassemia-related retinal changes. The association between systemic risk factors (age, type and duration of iron chelator use, history of splenectomy, hemoglobin level, and ferritin level) and thalassemia-related retinal changes was investigated using logistic regression analysis.

RESULTS

Thalassemia-related retinal changes were identified in 36.7% of patients. Several distinct retinal changes were observed, including retinal refractile bodies in 10% of patients and retinal hemorrhage in 5.8% of patients. Fundus autofluorescence imaging showed abnormal patterns in 36.3% of patients with thalassemia-related retinal changes and 18.4% of patients without thalassemia-related retinal changes. Age (odds ratio [OR] = 1.10, 95% confidence interval [CI] 1.03-1.18) and ferritin level (OR 1.16, 95% CI 1.01-1.33) were associated with thalassemia-related retinal changes.

CONCLUSION

Novel retinal changes were observed in β-thalassemia major patients. This study identified older age and higher ferritin level as risk factors for thalassemia-related retinal changes.

From membrane to mineralization: the curious case of the ABCC6 transporter

ATP-binding cassette subfamily C member 6 gene/protein (ABCC6) is an ATP-dependent transmembrane transporter predominantly expressed in the liver and the kidney. ABCC6 first came to attention in human medicine when it was discovered in 2000 that mutations in its encoding gene, ABCC6, caused the autosomal recessive multisystemic mineralization disease pseudoxanthoma elasticum (PXE). Since then, the physiological and pathological roles of ABCC6 have been the subject of intense research. In the last 20 years, significant findings have clarified ABCC6 structure as well as its physiological role in mineralization homeostasis in humans and animal models. Yet, several facets of ABCC6 biology remain currently incompletely understood, ranging from the precise nature of its substrate(s) to the increasingly complex molecular genetics. Nonetheless, advances in our understanding of pathophysiological mechanisms causing mineralization lead to several treatment options being suggested or already tested in pilot clinical trials for ABCC6 deficiency. This review highlights current knowledge of ABCC6 and the challenges ahead, particularly the attempts to translate basic science into clinical practice.

Pseudoxanthoma elasticum in childhood in patient with β-thalassaemia

Pseudoxanthoma elasticum (PXE) is a rare genetic disorder characterised by elastic tissue alterations and caused by mutations in a single gene, ABCC6, on chromosome 16p that includes manifestations that are predominantly cutaneous, ocular and cardiovascular. PXE-like lesions in association with β-thalassemia have previously been reported in the literature in patients with β-thalassaemia intermediate and major, being clinically indistinguishable from classic PXE. The case is presented of a 10-year-old boy with β-thalassaemia minor and characteristic lesions of PXE. It is worth noting the benefit of multimodal imaging in the diagnosis and monitoring of the lesions.

Late-onset Pseudoxanthoma Elasticum Associated with a Hypomorphic ABCC6 Variant

PURPOSE

To describe patients with late-onset pseudoxanthoma elasticum (PXE) associated with a likely hypomorphic ABCC6 variant.

DESIGN

Retrospective observational case series.

METHODS

Clinical evaluation, multimodal retinal imaging, genetic testing, and molecular modeling.

RESULTS

Three patients, in whom vision symptoms first arose at 80 years of age or later, showed age-related macular degeneration (AMD)-like fundus changes. However, features characteristic of PXE, including discrete angioid streaks and reduced fluorescence on late-phase indocyanine green angiography, prompted genetic testing which revealed the c.1171A>G variant in combination with a large deletion in the ABCC6 gene in each case. None of the patients had obvious skin changes or cardiovascular disease atypical for their age. Comparative molecular modeling supported the hypothesis that the c.1171A>G_ABCC6 variant acted as a hypomorphic variant.

CONCLUSIONS

Late-onset PXE extends the spectrum of ectopic calcification disorders caused by mutations in ABCC6 and may clinically be limited to the eye, mimicking AMD. Patients may be identified based on specific ocular changes, whereas skin and cardiovascular changes may remain ambiguous. The study provides evidence for a role for hypomorphic ABCC6 variants in the pathogenesis of PXE.

EYES WITH SUBRETINAL DRUSENOID DEPOSITS AND NO DRUSEN: Progression of Macular Findings

PURPOSE

To investigate the macular changes over time in eyes containing subretinal drusenoid deposits (also known as pseudodrusen) with no drusen >63 µm.

METHODS

A consecutive series of patients were examined with color fundus photography, optical coherence tomography, and autofluorescence imaging with fluorescein angiography used as necessary. Exclusionary criteria included macular neovascularization, history of retinal surgery, pseudoxanthoma elasticum, and drusen >63 µm.

RESULTS

There were 85 eyes of 54 patients. The mean age at baseline was 83.6 (±7.8) years, and there were 17 men. The mean follow-up was 5.0 (±2.9) years. At initial optical coherence tomography examination, 12 eyes had extrafoveal atrophy and 17 eyes had vitelliform deposits, which were yellowish white subretinal collections that showed intense hyperautofluorescence. During follow-up, 11 eyes lost vitelliform material. After the disappearance of small deposits, focal hyperpigmentation remained. Loss of larger deposits was associated with noteworthy sequela; six developed subfoveal atrophy and one macular neovascularization close to regressing vitelliform material. Subfoveal geographic atrophy developed in four other eyes without vitelliform material by extension from areas of extrafoveal atrophy. Macular neovascularization developed in seven eyes over follow-up. The CFH Y402H and ARMS2 A69S allele frequencies were 57% and 48.9%, respectively, which is similar to a group of age-related macular degeneration controls. One patient had a novel PRPH2 mutation, but did not have a vitelliform deposit; the remainder had a normal PRPH2 and BEST1 coding sequences.

CONCLUSION

Eyes with subretinal drusenoid deposits and no drusen >63 mm have significant risk for the development of both neovascularization and geographic atrophy, the fundamental components of late age-related macular degeneration. An intermediate step in some eyes was the development of a vitelliform deposit, an entity not traditionally associated with age-related macular degeneration, but in these patients, the material seemed to be an important component of the disease pathophysiology. This vitelliform deposit was not associated with genetic markers for pattern dystrophy or Best disease.

A Pilot Optical Coherence Tomography Angiography Study on Superficial and Deep Capillary Plexus Foveal Avascular Zone in Patients With Beta-Thalassemia Major

Purpose

To investigate foveal avascular zone (FAZ) changes in the superficial (SCP) and deep (DCP) capillary plexuses in beta-thalassemia major (BTM) patients, as shown in optical coherence tomography angiography.

Methods

Nonrandomized, comparative case series of 54 eyes of 27 BTM patients and 46 eyes of 23 healthy controls, utilizing an automated FAZ detection algorithm. Measurements included FAZ area and FAZ shape descriptors (convexity, circularity, and contour temperature). Results were compared between the two groups, and correlated to iron load and chelation therapy parameters.

Results

SCP and DCP FAZ area were not significantly different between the control and BTM groups (P = 0.778 and P = 0.408, respectively). The same was true regarding SCP FAZ convexity (P = 0.946), circularity (P = 0.838), and contour temperature (P = 0.907). In contrast, a statistically significant difference was detected between controls and BTM group regarding DCP FAZ convexity (P = 0.013), circularity (P = 0.010), and contour temperature (P = 0.014). Desferrioxamine dosage was strongly correlated to the DCP area (r = 0.650, P = 0.05) and liver magnetic resonance imaging/T2-star to DCP circularity (r = -0.492, P = 0.038). Correlations were also revealed between urine Fe excretion and DCP convexity (r = 0.531, P = 0.019), circularity (r = 0.661, P = 0.002), and contour temperature (r = -0.591, P = 0.008).

Conclusions

Retinal capillary plexuses and especially DCP seem to present unique morphologic changes in BTM patients, not in the FAZ area, but in specific shape descriptors, indicating minor but detectable FAZ changes. These changes correlate well with iron load and chelation therapy parameters. Their clinical importance and pathophysiologic implications remain to be elucidated through further studies.

Ocular abnormalities in beta thalassemia patients: prevalence, impact, and management strategies

BACKGROUND

Beta thalassemia (β-thalassemia) is a hereditary disease caused by defective globin synthesis and can be classified into three categories of minor (β-TMi), intermedia (β-TI), and major (β-TM) thalassemia. The aim of our study is to investigate the effects of β-thalassemia and its treatment methods on different parts of the eye and how early-diagnostic methods of ocular complications in this disorder would prevent further ocular complications in these patients by immediate treatment and diet change.

METHODS

We developed a search strategy using a combination of the words Beta thalassemia, Ocular abnormalities, Iron overload, chelation therapy to identify all articles from PubMed, Web of Science, Scopus, and Google Scholar up to December 2018. To find more articles and to ensure that databases were thoroughly searched, the reference lists of selected articles were also reviewed.

RESULTS

Complications such as retinopathy, crystalline lens opacification, color vision deficiency, nyctalopia, depressed visual field, reduced visual acuity, reduced contrast sensitivity, amplitude reduction in a-wave and b-wave in Electroretinography (ERG), and decrease in the Arden ratio in Electrooculography (EOG) have all been reported in β-thalassemia patients undergoing chelation therapy.

CONCLUSION

Ocular problems due to β-thalassemia may be a result of anemia, iron overload in the body tissue, side effects of iron chelators, and the complications of orbital bone marrow expansion.

Spectral domain optical coherence tomography findings in Turkish sickle-cell disease and beta thalassemia major patients

Purpose

To assess probable structural changes using spectral domain optical coherence tomography (SD-OCT) on sickle-cell disease (SCD) and beta thalassemia major (B-TM) patients, without any retinal abnormalities.

Methods

This cross-sectional study included 32 B-TM, 34 SCD patients, and 44 healthy controls. One of the eyes of all participants was evaluated for SD-OCT and choroidal thickness, retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), ganglion cell complex (GCC).

Results

Age, gender, and intraocular pressure (IOP) were not statistically different between the three groups. Hemoglobin (Hgb), hematocrite (Htc), and ferritin levels were not statistically different between the SCD and B-TM groups. Choroidal thickness at the subfoveal region was statistically higher in the control group (353.79 ± 71.93) than in the B-TM (317.41 ± 53.44) and SCD (283.21 ± 63.27) groups. In addition, it was statistically higher in the B-TM group than the SCD group (P = 0.05). CMT did not differ among the three groups, average RNFL was only significantly thinner in SCD than in controls, and GCC thickness was significantly thinner in SCD than in controls and B-TM.

Conclusion

In both diseases, we can show early structural changes even if proliferative or non-proliferative retinopathy or other ocular manifestations were not developed yet.

Unexpected ABCC6 mRNA splicing in a Chinese family with pseudoxanthoma elasticum

PURPOSE

To identify the clinical characteristics and pathogenic genes among a Chinese family with angioid streaks and to assess a novel splicing mutation at the transcriptional and translational levels.

METHODS

Consenting family members were clinically evaluated, and blood samples were collected for targeted exome capture sequencing and/or Sanger sequencing. The two affected siblings were assessed by multimodal fundus imaging. ABCC6 splicing patterns were analysed by RNA identification and quantification using the proband's peripheral blood mononuclear cells. Minigene experiments were performed to verify the university. Plasmids expressing the transcripts were transfected into HEK293 cells to assess protein translation. Bioinformatic analyses were also performed to predict the splicing patterns and the functional consequences of the mutation.

RESULTS

The two siblings were trans-compound heterozygous pseudoxanthoma elasticum (PXE) patients with the same genotype (c.3703C>T and c.1177-2A>G for ABCC6) but different phenotypes. We identified several ABCC6 alternative splicing transcripts that were not previously reported. The novel splicing mutation c.1177-2A>G led to the upregulation of three transcripts, one using a cryptic splice acceptor in the upstream region of the intron, another using a cryptic splice acceptor in the downstream exon, and the third stimulating non-canonical U12-type splicing. All the transcripts were successfully translated in vitro.

CONCLUSION

The genotype-phenotype correlation of PXE is poorly understood. The novel ABCC6 splicing mutation c.1177-2A>G results in multiple splicing patterns. Endogenous U2 to U12 conversion may occur in humans in a disease state. Peripheral blood mononuclear cells can be reliably used to study ABCC6 RNA.

Pattern dystrophies in patients treated with deferoxamine: report of two cases and review of the literature

Background

Deferoxamine (DFO) is one of the most commonly used chelation treatments for transfusional hemosiderosis. Pattern dystrophies constitute a distinct entity of retinal disorders that has been occasionally identified in association with deferoxamine.

Case presentation

We report two cases of bilateral macular pattern dystrophy in transfusion dependent patients undergoing chronic chelation therapy with deferoxamine due to thalassemias. Our patients were evaluated with multimodal imaging and the results are presented. Both patients had normal cone and rod responses in the full-field electroretinogram and continued the prescribed chelation therapy, after hematology consult. The patients were followed up every 3 months for 2 and 4 years respectively for possible deterioration. Their best corrected visual acuity remained stable with no anatomic change on Optical Coherence Tomography findings.

Conclusion

Multimodal imaging of our patients allowed a better evaluation and possibly earlier detection of the DFO-related changes. Screening and close follow up of patients under chronic chelating therapy is important in order to promptly diagnose and manage possible toxicity either with discontinuation of the offending agent or dose modification.

MULTIMODAL IMAGING OF ANGIOID STREAKS ASSOCIATED WITH TURNER SYNDROME

PURPOSE

To report multimodal imaging in a novel case of angioid streaks in a patient with Turner syndrome with 10-year follow-up.

METHODS

Case report of a patient with Turner syndrome and angioid streaks followed at Bellevue Hospital Eye Clinic from 2007 to 2017. Fundus photography, fluorescein angiography, and optical coherence tomography angiography were obtained.

RESULTS

Angioid streaks with choroidal neovascularization were noted in this patient with Turner syndrome without other systemic conditions previously correlated with angioid streaks.

CONCLUSION

We report a case of angioid streaks with choroidal neovascularization in a patient with Turner syndrome. We demonstrate that angioid streaks, previously associated with pseudoxanthoma elasticum, Ehlers-Danlos syndrome, Paget disease of bone, and hemoglobinopathies, may also be associated with Turner syndrome, and may continue to develop choroidal neovascularization, suggesting the need for careful ophthalmic examination in these patients.

Optic disk drusen in children

Optic disk drusen occur in 0.4% of children and consist of acellular intracellular and extracellular deposits that often become calcified over time. They are typically buried early in life and generally become superficial, and therefore visible, later in childhood, at the average age of 12 years. Their main clinical significance lies in the ability of optic disk drusen, particularly when buried, to simulate true optic disk edema. Misdiagnosing drusen as true disk edema may lead to an invasive and unnecessary workup for elevated intracranial pressure. Ancillary testing, including ultrasonography, fluorescein angiography, fundus autofluorescence, and optical coherence tomography, may aid in the correct diagnosis of optic disk drusen. Complications of optic disk drusen in children include visual field defects, hemorrhages, choroidal neovascular membrane, nonarteritic anterior ischemic optic neuropathy, and retinal vascular occlusions. Treatment options for these complications include ocular hypotensive agents for visual field defects and intravitreal anti-vascular endothelial growth factor agents for choroidal neovascular membranes. In most cases, however, children with optic disk drusen can be managed by observation with serial examinations and visual field testing once true optic disk edema has been excluded.

BILATERAL CHOROIDAL NEOVASCULARIZATION IN A PATIENT WITH BETA-THALASSEMIA MAJOR AND ITS MANAGEMENT

PURPOSE

To describe a case of bilateral choroidal neovascularization in a patient with beta-thalassemia major and an interventional therapeutic attempt.

METHOD

Retrospective case report.

RESULT

A known case of beta-thalassemia major presented with gradual vision loss. Fundoscopy revealed bilateral macular edema accompanied by intraretinal hemorrhages. Optical coherence tomography and fluorescein angiography were compatible with the diagnosis of choroidal neovascularization. No signs of angioid streaks or other related abnormalities were noticed in examination and imaging. The patient was treated with intravitreal bevacizumab, and visual acuity improved within 6 months of follow-up.

CONCLUSION

Bilateral choroidal neovascularization can be a presenting pathology in patients with beta-thalassemia major. Anti-vascular endothelial growth factor is a promising treatment option.

β-Thalassemia and ocular implications: a systematic review

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.

Retinal abnormalities in β-thalassemia major

Patients with beta (β)-thalassemia (β-TM: β-thalassemia major, β-TI: β-thalassemia intermedia) have a variety of complications that may affect all organs, including the eye. Ocular abnormalities include retinal pigment epithelial degeneration, angioid streaks, venous tortuosity, night blindness, visual field defects, decreased visual acuity, color vision abnormalities, and acute visual loss. Patients with β-thalassemia major are transfusion dependent and require iron chelation therapy to survive. Retinal degeneration may result from either retinal iron accumulation from transfusion-induced iron overload or retinal toxicity induced by iron chelation therapy. Some who were never treated with iron chelation therapy exhibited retinopathy, and others receiving iron chelation therapy had chelator-induced retinopathy. We will focus on retinal abnormalities present in individuals with β-thalassemia major viewed in light of new findings on the mechanisms and manifestations of retinal iron toxicity.

Functional and Structural Abnormalities in Deferoxamine Retinopathy: A Review of the Literature

Deferoxamine mesylate (DFO) is the most commonly used iron-chelating agent to treat transfusion-related hemosiderosis. Despite the clear advantages for the use of DFO, numerous DFO-related systemic toxicities have been reported in the literature, as well as sight-threatening ocular toxicity involving the retinal pigment epithelium (RPE). The damage to the RPE can lead to visual field defects, color-vision defects, abnormal electrophysiological tests, and permanent visual deterioration. The purpose of this review is to provide an updated summary of the ocular findings, including both functional and structural abnormalities, in DFO-treated patients. In particular, we pay particular attention to analyzing results of multimodal technologies for retinal imaging, which help ophthalmologists in the early diagnosis and correct management of DFO retinopathy. Fundus autofluorescence, for example, is not only useful for screening patients at high-risk of DFO retinopathy, but is also a prerequisite for identify specific high-risk patterns of RPE changes that are relevant for the prognosis of the disease. In addition, optical coherence tomography may have a clinical usefulness in detecting extent and location of different retinal changes in DFO retinopathy. Finally, this review wants to underline the need for universally approved guidelines for screening and followup of this particular disease.