CD4 and Schnyder corneal dystrophy: CD4+ T cells were found to be reduced in percentage in SCD patients (19.6% vs. 25.4%, p-value ≤.001) with an increase in percentage of CD4+ CD45RO + cells (39.6% vs. 31.1%, p-value ≤.05) and central memory CD4+ T cells (20.6% vs. 12.2%, p-value ≤.05).