A delicate type of surgery to relieve pressure in the optic nerve is preventing blindness in women with a relatively uncommon disorder. The technique, developed by doctors at the University of Maryland Medical Center, has restored normal vision in 29 of 30 patients. The disorder, called pseudo tumor cerebri, creates nerve-damaging pressure in the eye, and it strikes 19 of every 100,000 young adult women, said Dr. Shalom E. Kelman, director of neuro-ophthalmology. Although patients are treated with drugs or spinal drains that reduce the fluid pressure in the central nervous system, many don't respond and lose their sight, he said. The Maryland procedure involves cutting several tiny holes in the sheath covering the optic nerve, allowing the fluid to drain. For patients who do not respond to other treatments, the new surgical technique is an eye saver, Kelman reported at the annual meeting of the American Academy of Ophthalmology. Chewing gum risk