Electrophysiological assessment for early detection of retinal dysfunction in ß-thalassemia major patients.

PURPOSE: The purpose of this study was to assess the role of various diagnostic tests in early detection of retinal changes in ß-thalassemia major patients. METHODS: Thirty-eight visually asymptomatic ß-thalassemia major patients receiving regular blood transfusions and iron-chelation therapy with deferoxamine (group A, n = 13), deferasirox (group B, n = 11) or deferoxamine with deferiprone (group C, n = 14) and fourteen age- and sex- matched healthy individuals were included in the study. All participants underwent ophthalmoscopy, full-field electroretinography (ERG), visual evoked potentials (VEP), multifocal electroretinography (mfERG), fundus autofluorescence (FAF) imaging and optical coherence tomography (OCT) scans. RESULTS: Retinal pigment epithelium changes were present in two cases. Scotopic ERG demonstrated decreased a-wave amplitude in groups A, B and C (p = 0.03, p = 0.002 and p = 0.002, respectively) and decreased b-wave amplitude in groups B and C (p = 0.002 and p = 0.01, respectively) compared to controls. Photopic ERG showed delayed b-wave latency in groups A and C (p = 0.03 and p = 0.03, respectively) ERG maximal combined response and VEP response did not differ between groups. MfERG showed reduced retinal response density in ring 1 in groups A, B, C (p < 0.001, p < 0.001, p = 0.001, respectively) and ring 2 in group B (p = 0.02) and delayed latency in ring 5 in groups A and B (p = 0.04 and p = 0.04, respectively). Abnormal FAF images appeared in three cases and OCT abnormalities in one case, whereas no changes were observed in controls (p = 0.55 and p = 1.00, respectively). CONCLUSIONS: Full-field ERG and mfERG are more sensitive tools for detecting early retinal changes in ß-thalassemia patients compared with ophthalmoscopy, VEP, FAF imaging and OCT scans.