Medical Laser Applications

In the early days of lasers, it came as a surprise that these tools of light could be used in the science of medicine since no one envisioned that they might be able to heal or otherwise improve people's physical well-being. But doctors and medical researchers quickly began to see the possibilities, and the number of uses for medical lasers multiplied over the years. Among other applications, these include cutting into tissue in surgical procedures; reshaping the cornea of the eye to improve sight; cleaning clogged arteries; burning away cavities and whitening the teeth; removing unwanted hair, wrinkles, birthmarks, and freckles; and reshaping the face in plastic surgery procedures.

The highly collimated beam of a laser can be further focused to a microscopic dot of extremely high energy density. This makes it useful as a cutting and cauterizing instrument. Lasers are used for photocoagulation of the retina to halt retinal hemorrhaging and for the tacking of retinal tears. Higher power lasers are used after cataract surgery if the supportive membrane surrounding the implanted lens becomes milky. Photodisruption of the membrane often can cause it to draw back like a shade, almost instantly restoring vision. A focused laser can act as an extremely sharp scalpel for delicate surgery, cauterizing as it cuts. ("Cauterizing" refers to long-standing medical practices of using a hot instrument or a high-frequency electrical probe to singe the tissue around an incision, sealing off tiny blood vessels to stop bleeding.) The cauterizing action is particularly important for surgical procedures in blood-rich tissue such as the liver. Lasers have been used to make incisions half a micron wide, compared to about 80 microns for the diameter of a human hair.

Since the laser is powerful enough to cut through solid steel, it may also be capable of destroying cancer cells. The effectiveness of the laser as an anti-cancer weapon was described at a meeting of the American College of Surgeons in San Franciso. They reported that several hundred human cancers transplanted to hamsters have been destroyed by exposure to the beam of the laser developed by Raytheon. According to researchers, however, experiments have not yet progressed far enough for definite conclusions.