ELECTRORETINOGRAPHIC AND VISUAL-EVOKED POTENTIAL CHANGES IN RELATION TO CHELATION MODALITY IN CHILDREN WITH THALASSEMIA

Purpose: To evaluate possible benefits of using electrophysiological investigations for detecting retinal and visual pathway changes and correlating them with chelation modality in children with thalassemia. Methods: This study included 60 patients on single oral iron chelator (deferasirox) (Group 1), 60 on deferoxamine chelator (Group 2), and 60 controls (Group 3). Participants underwent full ophthalmologic examination, pattern visual-evoked potential, pattern electroretinogram, and multifocal electroretinogram. Results: Fundus showed no abnormalities. Multifocal electroretinogram mean P1 amplitude showed statistically significant differences in all 5 rings, amplitudes being significantly lower in Groups 1 and 2 than Group 3; moreover, significantly lower in Group 2 than Group 1. There was a statistically significant difference between groups regarding P50 wave latency and N35-P50 of pattern electroretinogram amplitude (P < 0.001 and P, 0.001, respectively). However, there were no statistically significant differences between groups regarding N95 wave of pattern electroretinogram and pattern visual-evoked potential waves' amplitude and latency. Multiple regression analyses illustrated that chelator was the most important determinant for multifocal electroretinogram and P50 parameters. Conclusion: Preclinical electrophysiologic changes existed in thalassemics, more obvious in those on deferoxamine. Electrophysiologic studies analysis denotes an early toxic macular insult rather than optic nerve affection. Thus, regular follow-up using multifocal electroretinogram and pattern electroretinogram is recommended.