Cyclosporine brings tears to dry eyes.

Cyclosporine brings tears to dry eyes

A form of "dry eye" that causes constant pain and gradual loss of sight, apparently due to an autoimmune response, may be treatable with minute quantities of the immune-suppressing drug cyclosporine applied directly to the eye, medical researchers reported this week.

While many cases of dry eye are caused by vitamin A deficiency or facial nerve damage, evidence indicates the disorder also can stem from destruction of the tear glands by the body's own immune cells. The immune reaction can occur suddenly or progress slowly, leading to corneal inflammation, infection and ulcers. Often associated with rheumatoid arthritis, this type of dry eye afflicts an estimated 3.2 million people in the United States, according to the researchers, and many more have a mild form of it. Until now there has been no treatment for the cause of the disorder, called keratoconjunctivitis sicca, although its symptoms can be controlled, according to Renee Kaswan of the University of Georgia in Athens.

"It was thought that eye disease caused by autoimmunity would require immunosuppression of the entire body," Kaswan says. But cyclosporine's toxicity to the kidneys when given orally caused most researchers to dismiss it as a treatment for dry eye. However, when Kaswan and her colleagues tested cyclosporine eye drops in dogs, they found the drug substantially restored tearing, reduced corneal scar tissue and speeded the healing of corneal ulcers. In addition, they say, it may prevent further tear-gland destruction in all but in the most advanced cases.

Even in dogs whose tear production did not improve, the researchers observed a "marked reduction" in corneal scarring. They have successfully treated dogs for up to two years without adverse effects, and when they stop the drug, the dogs' tears dry up within a day or two, they say. By applying the drug directly to the damaged area, the researchers were able to reduce dosage to 1 percent of the oral dose. Kaswan reported the group's findings at a seminar in Arlington, Va., sponsored by Research to Prevent Blindness.

In a pilot study nearing completion at the University of Glasgow in Scotland, a cyclosporine ointment used to treat 12 people with dry eye has produced encouraging improvement, Kaswan says. A larger clinical trial at four U.S. medical centers is scheduled to begin early next year.

"It works in dogs. If equivalently effective in people, it will be a breakthrough," Kaswan told SCIENCE NEWS.