GSTM1 and Schnyder corneal dystrophy: A total of 85 SCD patients (52 males and 33 females) with both sickle cell anemia (HbSS) and hemoglobin sickle-beta-thalassemia (Hb S/β-Thal) genotypes at the steady state, and 30 healthy controls, were enrolled in this cross-sectional study with no age limits.