Purpose: Evaluation of contrast sensitivity in patients with beta-thalassemia major and sickle cell disease which undergo regular transfusions and chelation therapy with desferrioxamine (DFX).Materials and Methods:We studied contrast sensitivity in 48 eyes (24 patients) with beta-thalassemia major (group A) and in 42 eyes (21 patients) with sickle cell disease (group B), compared to 60 eyes of 30 healthy individuals (control group). Contrast sensitivity was measured using B-VAT II-SG Mentor Video Aquity Tester.Results: We found no statistically significant difference between group A and group B in any spatial frequency, while we found statistically significant differences between group B and control group in all spatial frequencies studied. Between group A and control group we found statistically significant differences in spatial frequencies of 2.3, and 6 cyc/deg.Conclusion: DFX causes retinal alterations that may explain reductions in contrast sensitivity function and justifies regular evaluations that may allow early detection of visual function deterioration.