Figure 4. DNA damage in rabbit corneas following treatment with MMC. γH2AX staining (green) and DAPI staining (red) of the anterior (A) and posterior (B) cornea following MMC treatment. Note that the most anterior keratocytes show only DAPI staining (arrowhead) suggesting apoptosis, while the remaining keratocytes (A, arrow) and posterior endothelial cells (B, arrow) show γH2AX staining. Quantification of γH2AX staining intensity (C) showed that 0.2 mg/ml MMC produced significantly greater staining compared to corneas treated with 0.02 mg/ml, and that 60 s exposure produced significantly greater staining compared to 15 s. It should also be noted that there was no significant difference (NS) in staining between cells in the anterior or posterior cornea.