Made from Beauvaria nivea, a soil fungus, the immune-system-suppressing drug cyclosporine was developed to prevent rejection in organ transplant patients. The cyclosporine eye drop formula is used to treat keratoconjunctivitis sicca, or KCS, in dogs. Nearly 40 percent of dogs suffering from eye problems have KCS. Cocker spaniels, Yorkies, Shih Tzus and bulldogs are among the breeds most frequently affected. Also known as dry eye, KCS occurs when an animal's immune system suppresses tear production. The lack of tears causes irritation, browning of the cornea and thick discharge. If untreated, it can result in blindness.