Mitomycin C is a chemotherapy drug that is used in cancer to stop the production of new tissue. In glaucoma surgery it is used to reduce scarring. Scarring causes failure of the trabeculectomy as the fluid cannot flow out of the eye. During the surgery, Mitomycin C may be applied to the surface of the eye for about 3 minutes. The Mitomycin C is then washed away from the eye with sterile water so that there is no drug left in the eye.