The Protective Effect of Fetal Hemoglobin on Retinal Damage in Sickle Cell Disease Patients: A Correlation with Optical Coherence Tomography, Hematologic Parameters, and Hydroxyurea Treatment

ABSTRACT Purpose The protective effect of fetal hemoglobin (HbF) on retinal health in patients with sickle cell disease (SCD) has been well recognized. Hydroxyurea, a disease‐modifying agent, induces HbF production and modifies hematologic parameters. This study investigated the correlation between retinal damage on optical coherence tomography (OCT) and HbF levels. Additionally, it compared retinal OCT, HbF, and other hematologic laboratory parameters in patients treated with/without hydroxyurea. Methods In this prospective, observational study, 138 patients with SCD underwent ophthalmologic examination, including OCT. Hematologic values and treatment history were obtained from medical records. Analyses focused on correlations between HbF levels and hematologic markers, HbF trends with age in children with/without abnormal retinal OCT, and the impact of hydroxyurea treatment on HbF levels and OCT results. Results Children with normal retinal OCT exhibited a slower age‐related decline in HbF levels before age 15 years compared with those with abnormal OCT. HbF levels showed a strongly negative correlation with markers of hemolysis and inflammation and a positive correlation with hemoglobin. Hydroxyurea treatment was associated with elevated HbF levels and a shift in hematologic profile toward those observed in patients with normal OCT findings. Children treated with hydroxyurea exhibited slower progression of macular thinning with age. Conclusions Children with normal OCT findings maintained higher HbF levels and showed a slower decline with age. Hydroxyurea treatment increases HbF levels, improves hematologic profiles, and reduces the likelihood of retinal abnormalities. Further research is needed to elucidate the mechanisms behind these observations and validate the findings in larger datasets.