Abstract
Purpose :
Patients of the same sickle cell disease (SCD) genotype present significant heterogeneity in their clinical manifestations. Identifying factors predictive of organ damage will allow early treatment before repeated hypoxic-ischemic insults to the retina, thus improving long-term outcomes. We have shown that low fetal hemoglobin (HbF) levels and elevated reticulocyte count (retic) are associated with retinal injuries in children with SCD. HbF interferes with hemoglobin polymerization, and retic is a marker of hemolytic activity. Hydroxyurea (HU) increases the production of HbF and reduces white blood cells that contribute to the general inflammatory state. We examine their effect on ocular health in children with SCD.
Methods :
In this prospective longitudinal cohort study, all patients underwent complete ophthalmologic examination and OCT imaging. SCD-related medical history, brain imaging, laboratory tests, and medical treatment were collected and analyzed using the Chi-square test for categorical data and the nonparametric test for continuous variables. The relationship between age, HU treatment, test values, and retinal OCT was examined.
Results :
Since 2015, 118 patients with SS-type SCD, 60 males, age 4.44 – 21.88 years, enrolled in the study. Data from 299 eye examinations and hematology laboratory tests from the period were collected. Abnormal retinal OCT increases with age. Patients treated with HU showed a significantly slower rise in cumulative case percentage (p=0.006). Compared to untreated cases, patients receiving HU had normal OCT at an older age, lower WBC, retic, AST, and i-bili levels, and higher HbF. However, the effect of HU is complex; although HU significantly increases HbF levels for children with abnormal OCT (p=0.000), its effect for those with normal OCT is insignificant (p=0.935[MRE1] ); perhaps those with normal OCT maintained higher HbF even before initiation of HU.
Conclusions :
These data suggest that HU may preserve retinal structure by OCT among children with SS-type SCD. HU increases HbF, reduces inflammatory and hemolytic activity. Monitoring these hematologic parameters throughout childhood may identify patients at higher risk for subsequent retinal injuries who might benefit from early disease-modifying treatments. These critical findings require further study in a larger patient population undergoing serial exams.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.