Zapping disease.

In a giant leap from fiction to fact, the laser has pulsed a long way since Luke Skywalker mustered his courage and aimed the powerful beam at his nemesis Darth Vader.

During the past 17 years the technology has become a weapon in the battle against a more earthly enemy--disease.

The laser is being recruited by surgeons to zap trouble bodywide, particularly beneficial in hard-to-reach or delicate areas with small operative fields, such as the eye, fallopian tube, or mouth.

Specialists boast the high-tech instrument that can minimize such scalpel drawbacks as bleeding, swelling, bruising, scarring, pain, and lengthy recovery. Yet as with any new technology, glitches remain to be worked out.

Lasers--gas, liquid or solid; visible or unseen; of one or more colors; continuous wave or several-billionths-of-a-second pulse--were not all created equal to slice, weld, or obliterate.

"The trick is to know when to use which kind," says Dr. Robert Pick, president of the American Academy of Laser Dentistry.

Mastering the complexities of the laser--which, in the wrong hands, can start fires, harm eyes, char a cheek or chip a tooth, explode, or even electrocute--requires years of practice.

"The laser is not something an unskilled physician could pick up and use," says Dr. Gregory Keller, medical director of the Western Institute for Laser Treatment in Santa Barbara, California.

But properly used, this high-tech tool is performing wonders. Here is a sampling of what it can do:

Ophthalmology. Introduced into medicine as a tool to seal leaking blood vessels in the eye, the laser is widely accepted in surgery for retinal diseases (many suffered by diabetics), glaucoma, and secondary membrane formed after cataract removal.

"Lasers have really turned the tide for many patients who would have gone blind in the past," says Dr. William Ellis, director of the Eye Center of Northern California in El Cerrito.

Obstetrics-Gynecology. Lasers are in demand for gynecologic surgery, the most common operation in the United States, with hysterectomies alone numbering 650,000 a year.

Employed to remove ovarian cysts, unblock fallopian tubes to reverse infertility, and treat urinary incontinence or ectopic pregnancy, lasers also offer an alternative to hysterectomy for uterine bleeding--one that preserves childbearing capability.

Surgeons opt for the laser in about half of procedures for endometriosis, a common disorder resulting when renegade tissue escapes from the uterine lining and colonizes other organs.

"The laser has allowed us to avoid almost all major gynecologic surgeries for benign and malignant conditions," comments Dr. Camran Nezhart, a Stanford University professor who pioneered a revolutionary method called "videolaseroscopy," which gives the surgeon a clear view--and shot--at the abdominal cavity.

"Operating in the uterine cavity is a big step forward in women's medicine, to which lasers lend themselves very well," adds Dr. Michael Baggish, head of ob-gyn at Good Samaritan Hospital in Cincinnati, Ohio.

Dentistry. As bloodless, sutureless negotiators of the curves and folds in the mouth, lasers get high marks in wiping out frenums, the skin flaps under the lip and tongue; canker sores; herpes lesions; oral tumors, and excessive gums.

Recent research has produced good news for ice cream lovers (lasers appear to reduce tooth sensitivity to cold) and dental drill haters (light beams can remove tooth decay, perhaps someday providing a kinder, gentler alternative to the dreaded drill).

Dermatology. Lasers are proving their worth for zapping warts, moles, precancerous lip growths, and the once-permanent tattoos.

"No other method has such a power of removal without blemish or pain," according to Dr. Robin Achinoff, chief of dermatologic and laser surgery at New York University.

Cosmetic surgery. Whether removing a birthmark from a baby's face or wiping away a liver spot from an aging hand, lasers have opened up worlds where cosmetic surgeons previously dared not tread.

"With traditional techniques, these procedures carried unacceptable risks of scarring," says Dr. Gary Lask, associate professor at the University of California, Los Angeles.

San Francisco plastic surgeon Dr. Michael Kulick has traded blade for laser in treating multiple skin malignancies. In the emerging "photodynamic therapy," laser light selectively activates drugs to kill the cancer without harming healthy cells.

Urology. Urologists use lasers to zap polyps that can develop into colon cancer and, in a much newer application, to vaporize tissue blocking the flow of urine in a high-tech takeoff on the traditional prostatectomy, men's second most common operation. As Dr. Maurice Sandler of Brookside Hospital in San Pablo, California, says: "The laser is ideal for some small enlargements of the prostate. No cutting, no bleeding."

Gastroenterology. Lasers speedily fragment gallstones trapped in the common duct between the liver and intestine, allowing their retrieval and stymieing a potentially deadly condition.

The gallbladder can be removed harmlessly but not so the duct, which is needed for survival, say surgeons.

Limited uses. While laser technology has exceeded expectations in many areas of medicine, it hasn't yet lived up to the high hopes in some.

Cardiovascular surgery. "The view of lasers as a magic silver bullet for coronary disease has fallen like a ton of lead," according to Dr. George Abela, associate professor of medicine at Harvard Medical School.

Lasers have made a hit in blasting blockages only at the highly elastic mouth of the artery that comes off the aorta, a site notoriously difficult to treat with balloon angioplasty.

Neurosurgery. Having failed to live up to its initial billing as a cureall for brain cancer, the laser serves mainly to remove hard-to-reach benign tumors at the base of the skull or in the head and to vaporize herniated discs in the spine.

Orthopedics. New to this field, lasers mostly are confined to removing torn tissue in arthroscopic knee and shoulder surgery.

"What would make a big difference is finding something lasers can do that mechanical instruments can't," says Dr. James Garrick, medical director of the Sports Medicine Center at St. Francis Memorial Hospital in San Francisco.

On the horizon. In a move to extend the laser frontiers, scientists from Lawrence Livermore National Laboratory, a birthplace of the Star Wars technology, and the Beckman Laser Institute in Irvine, California, will develop lasers to treat lung, bladder, head, neck, and gynecologic cancers, remove birthmarks, and aid fertility by drilling tiny holes in egg surfaces to ease sperm entrance.

"We are pursuing lasers because the physics is so complex and interesting that lurking in all the light wavelengths has got to be the right one that will do what everyone has envisioned lasers will do," says Dr. Michael Berns, director at Beckman.