After in vitro stimulation with PMA/ionomycin (PMA/Io) (polyclonal stimulation), a significantly higher frequency of IL4+TCD4+ cells in SCD and SCD/ON were detected in comparison to the control (0.19% (range 0.01-0.55) vs. 2.54% (range 1.98-4.41) and 0.19% (range 0.01-0.55) vs. 2.08% (range 0.57-4.15)) (p = 0.0016 and p = 0.0017, respectively) (Figure 3). This evidence concerns the gene IL4 and Schnyder corneal dystrophy.