Abstract
Purpose:
To evaluate biomarkers of hyperviscosity (hemoglobin levels, Hb) and hemolysis (lactate dehydrogenase, LDH levels) and correlate their role in ocular microangiopathy (conjunctival telangiectasia, non-proliferative and proliferative retinopathy).
Methods:
Ocular and systemic features of 201 patients with Sickle cell disease (SCD) was reviewed. Institutional review board (IRB) approval was obtained. Their ages ranged from 8 to 60 years. One hundred and twenty one (121) were homozygous sickle cell (SS), 27 were sickle beta-thalassemia (SB+, SB0), 46 were heterozygous sickle cell (SC) and 7 were minor heterozygous genotypes (S-Arab, S-hereditary spherocytosis & others). Total hemoglobin and fetal hemoglobin levels, LDH Levels, proteinura and use of hydroxyurea, were compared against ocular findings that included conjunctival telangiectasia, non-proliferative and proliferative retinopathy (microangiopathy).
Results:
Total Hb levels ranged from 10.12 to 14.02 gm/dL in the SC group, from 8.75 to 10.88 in SB group and from 6.79 to10.52 in SS group. The ocular microangiopathy was most severe in the SC group that had the higher total hemoglobin levels. In the SS sub group, the mean LDH level was 593.95 in the retinopathy group versus 378.80 in the no-retinopathy group, the difference was significant. In the SB sub group, the mean LDH level was 417.50 in the retinopathy group and 362.32 in the no-retinopathy group. The LDH levels in the SC subgroup were comparable between the retinopathy and no-retinopathy groups. Among the 64 patients who were receiving hydroxyurea, the mean fetal Hb was 11. 60% while those not receiving hydroxyurea had a mean fetal Hb of 6.67%.
Conclusions:
Higher LDH levels correlated with more severe retinopathy, suggesting a role for hemolysis in causing microangiopathy. Patients with SC genotype had higher total Hb, resulting in higher viscosity that is likely contributing to the angiopathy. Higher fetal Hb was seen in patients receiving hydroxyurea, which tended to protect against ocular microangiopathy.
Keywords: 749 vascular occlusion/vascular occlusive disease