GSTM1 and Schnyder corneal dystrophy: Similar to the above observation, our analysis showed that free plasma Hb levels above 40ug/ml, evident of intravascular haemolysis, were significantly associated with abnormal FEV1% predicted (< 80% predicted) and this was consistent with findings by Sylvester et al. who found an association between FEV1% predicted and markers of haemolysis among SCD patients [41].