Laser therapy

Related Terms

Birthmarks, cold laser therapy, contact laser systems, energy transformation, LASEK, LASER, laser acupuncture, laser cancer treatment, laser hair removal, laser therapy, LASIK, Light Amplification by the Stimulated Emission of Radiation, light beams, low-level laser therapy irradiation, low-power laser, noncontact laser systems, pain management, PDL, pulsed dye laser, urological lasers.

Background

Laser therapy is the use of amplified beams of light called lasers to diagnose or treat medical conditions.
Albert Einstein established the theoretical foundation for lasers in a 1917 paper on the quantum theory of radiation. He won the Nobel Prize for this work. He described the existence of a photon, which is a particle of light that is critical in the development of laser technology.
Lasers became popular in medicine in the 1960s for cosmetic and pain management uses and urological procedures.
The first working laser was developed by Dr. Theodore Maiman, who investigated the glare of a flash lamp in a rod of synthetic ruby to produce red laser light. A physicist at Hughes Aircraft Company, Maiman demonstrated the laser he built on July 7, 1960 at a news conference in Manhattan.
The laser involves exciting atoms and passing them through a medium such as crystal, gas, or liquid. As the cascade of photon energy sweeps through the medium, bouncing off mirrors, it is reflected back and forth. It gains energy to produce a high-wattage beam of light.
Lasers have four main parts: the active medium, the excitation mechanism, the feedback mechanism, which is usually a reflective mirror, and the output coupler.
Lasers are named for the liquid, gas, solid, or electronic substance that is used to create light. Lasers that have carbon dioxide gas as the medium are often used to treat snoring or for cosmetic resurfacing, such as to smooth out skin damaged by acne. The strength of the laser light determines how it is used in medicine.
Laser light differs from the natural light of the sun. Laser light is created by controlled emissions rather than by spontaneous emissions. This allows a doctor to target a specific tissue, as the light is focused and can be turned on and off easily. Laser light is targeted and not spread out in all directions like the light from the sun or a light bulb. Laser light is highly focused and only travels in one direction, unlike other lights, such as fluorescent or incandescent lights. Unlike natural light, all light beams from lasers have the same wavelength.
There are two major types of lasers, contact and noncontact, used in medicine. Contact lasers work by sending a light through a fiber or sapphire tip. The tip absorbs energy and becomes hot. When the hot tip touches any live tissue in the body, the target cells are vaporized, which is the removal of tissue through the conversion of a solid to a gas. Noncontact lasers do not touch the tissue. They operate by transferring laser light as radiant energy in a single beam to the tissue. Heat results when the cell absorbs this energy. In both cases, the laser light is not hot. Heat is only created after the laser's radiant energy is absorbed by the targeted tissue.
Contact lasers can be used for cutting through bone as well as pulverizing kidney stones. A common contact laser is called the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. This laser can go deep into the tissue and even cause blood to clot. It is often used in cancer patients.
Some noncontact lasers are used with laser light-sensitive drugs. Such a drug is administered to a patient, and over time, the drug is absorbed into tumor cells only. By exposing the drug in the cancer cells to the laser, a chemical reaction occurs. This kills the cancer, but most healthy cells are not affected. This is called photodynamic therapy.
High-energy lasers emit 10-100 watts of energy. Today, most lasers used in medicine are low-level energy emitters. Their output is 1/10-1/1,000weaker than the high-energy lasers. Wavelengths on these low-levels lasers are 300-6,000 nanometers. Some lasers are used with endoscopes, so that a doctor is able to see inside the body and direct the laser to the affected area. An endoscope is placed down the throat of a person. It has a camera on the tip, so that the doctor can see the lining of the throat and stomach.
Common uses of lasers include stimulation of hair growth, hair removal, surgical procedures (e.g., the removal of a growth in the kidney or the bladder or to cut through tissue), removal of tattoos, acne treatment, laser acupuncture to relieve pain, varicose vein removal, wrinkle removal, and treatment of some cancers.
Dr. David Baxter of the Centre for Physiotherapy Research in New Zealand advocates the use of low-level lasers to reduce pain and inflammation. People who have the following conditions may benefit from this type of laser: high blood pressure, headaches, osteoarthritis, osteoporosis, tissue or nerve damage (such as carpal tunnel syndrome), wound healing, fatigue, and fibromyalgia.
Low-level lasers may also be useful in the practice of acupuncture in traditional Chinese medicine (TCM).
Lasers are likely to be used more in the future for many medical conditions. The American Cancer Society? states that for cancer patients, lasers offer faster recoveries. However, it cautions that until more physicians and nurses become trained, widespread use is limited.
In 1995, the U.S. Food and Drug Administration allowed the first laser for hair removal, the SoftLightTM Nd:YAG by ThermoLase. Since its approval, laser treatment has gained popularity for hair removal.

Theory / Evidence

General: The use of lasers for many medical procedures is well established. Lasers are beneficial because they are more precise than other instruments, such as scalpels, used during surgery. In addition, there may be less scarring with lasers, the procedure may take less time, and the healing time may be faster. They have also been used for many cosmetic procedures, such as hair removal.
According to the Pain Center LLC of Ramsey, NJ, lasers used in medicine work by the stimulation of the molecules that are part of cells' transport mechanisms. These molecules are found on the surface of the cells, directly inside the outer membrane of the cell, and inside the energy-making parts of the cell, called the mitochondria. The laser causes changes in the release of compounds, which may support healing or reduce pain. There could be an increase in the release of natural substances that improve blood flow, stimulate new cell growth by increasing DNA and RNA synthesis, increase antioxidant production, normalize tissue's acid-base balance, or increase the rate at which the body makes energy as adenosine triphosphate (ATP).
Eye surgery: One of the most popular uses of lasers is for the correction of poor eyesight by laser-assisted in situ keratomileusis (LASIK), which can correct nearsightedness, farsightedness, and astigmatism. The laser is used to reshape the cornea and focus images correctly on the retina. Many people are good candidates for this procedure and are able to see well without eyeglasses after the procedure.
Lasers may also remove eye tumors and cataracts.
Diabetic complications: Lasers have been useful in treating conditions associated with diabetes. Many individuals with this condition develop an eye disease called diabetic retinopathy. Vision becomes impaired, and many people lose their sight. A double-frequency neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is most often used for treatment. The laser is directed toward the retina. According to one study, laser therapy may reduce the chance of vision loss by 50% compared to no treatment. Lasers may also help patients with eye swelling called macular edema.
Nonmelanoma skin cancer: Lasers may be used to prevent and treat nonmelanoma skin cancer. The laser causes an increase in reactive oxygen-containing molecules, which are focused to attack diseased tissue. Lasers used for this procedure are highly efficient and have a low level of invasiveness.
Breast cancer: Lasers may be used to reduce the size of breast cancer masses. Patients getting a scanning laser rather than a concentrated laser may experience volume reduction, improved subjective symptoms, and improved quality of life after the procedure, but both are effective. The best results were seen three months after laser treatment. According to one study, laser treatment may continue working after it has been administered.
Throat cancer: Patients being treated for throat cancer seemed to benefit from laser therapy. Compared to chemotherapy, those who got laser treatments had better survival rates and had more normal speech after surgery, according to one study. Devices used on these patients include carbon dioxide lasers and pulse-dye or potassium-titanyl-phosphate lasers. However, the American Broncho-Esophagological Association cautions that lasers are not appropriate for all type of throat cancers. It is necessary to speak to a doctor to determine whether laser treatment is appropriate for an individual's particular cancer.
Pain: Pain management is one of the most common reasons that laser treatment is used. For instance, laser acupuncture involves the use of a low-level laser. This form of phototherapy has been shown to be an effective alternative to the needles used in traditional acupuncture. Low-level lasers may also be useful in the practice of acupuncture in traditional Chinese medicine (TCM), as discussed in a review article published in Medical Acupuncture by board-certified acupuncturist Jos? Vargas.
Laser acupuncture has been used for the treatment of tennis elbow; muscle pain; knee, neck, and back pain; tension headaches; face, shoulder, and chest pain; fibromyalgia; postoperative vomiting and nausea; bed-wetting; and bladder inflammation, as well as for adolescent smoking cessation. However, according to one study, of these conditions, those in which the laser acupuncture was most effective were face pain, postoperative nausea and vomiting, and tension headaches. Low-level lasers were more effective at reducing chronic spinal pain from osteoarthritis than at reducing pain in the temporomandibular joint (TMJ), which is commonly known as jaw pain, according to one study.
Low-intensity laser therapy is effective in reducing neck pain immediately after its development, according to one study. People may remain free of pain after laser treatment for up to 22 weeks, based on a meta-analysis including 820 patients. Those who have chronic neck pain may also derive benefit. Side effects are typically uncommon from this sort of laser treatment when it is used for neck pain. People may also undergo laser therapy to treat pain associated with varicose veins. Sometimes these veins cause poor blood flow to the legs, leading to pain and night cramps. The vein problem does not reoccur after laser therapy over a two-year period in more than 90% of treated patients, according to one study.
Tendon injury: According to a systematic review of 25 articles, 12 showed clinical effectiveness of low-level laser therapy in the treatment of tendon injury. The remaining studies were inconclusive or showed no effect.The authors found that the studies with positive results provided patients with an effective dose of laser therapy which resembled treatment guidelines. They concluded that low-level laser therapy may be effective in treating tendon injury at recommended doses.
Urological disorders: Lasers may be useful to treat some urological problems. Specific lasers are needed, depending on the problem. For example, men with enlarged prostates often undergo a procedure called a transurethral resection, which opens up part of the prostate gland. It is possible to use lasers to perform this procedure. However, some laser surgery may not be more effective than conventional surgery. A doctor skilled with using lasers needs to select the most appropriate therapy and laser type.
Hair removal: Lasers are popular treatments for hair removal. The number of hair follicles is reduced, so that less hair is present after a single treatment. Unless the hair is removed when it is in a dormant state, called the anagen, which is a phase of the hair follicle cycle, some hair may grow back. The rate at which the hair follicle goes in and out of a dormant state varies around the body. Hair usually takes about 4-12 months to regrow. Hairs on the face come back first, and body hair usually takes longer. Follow-up treatments may be needed.
Lasers used for hair removal include the Ruby 694, which produces 694 nanometers of red light. In many cases, substantial hair regrowth is lacking two years later. Another device is called the 755 nanometer Alexandrite laser. Treatment is fast, requiring two milliseconds. Results may be effective for up to 15 months with this device when treatments occur about every three months. This laser can be used to remove facial hair, pubic hair, and hair under the arms. The short-pulsed nanosecond Q-switched Nd:YAG laser does not appear to be as effective as the other two types, according to one study.
Skin discoloration: Dark skin patches, such as freckles, sunspots, port wine stains, birthmarks, and scars, may be lightened safely and easily with lasers, according to one study. Depending on the darkness level, the laser energy and wavelengths used will vary. Van Buren and Alster report that the pulsed dye laser (PDL) has the best clinical track record for port wine stains and other vascular lesions, such as hemangiomas.
A laser imaging device was developed by scientists at Scripps Clinic and Beckman Laser Institute in Irvine, CA. This may be used with the PDL to assure that the affected area is properly treated to enhance a quick and effective response.
Tattoo removal: Tattoo removal should only be performed with Q-switched lasers (i.e., alexandrite, ruby, and Nd:YAG), according to Dr. Sabrina Wenzel of the Department of Dermatology at the University of Regensburg in Germany. Each type of laser works on a specific color in order to be effective. Some benefit to tattoo lightening may be seen immediately, but some people require 10 or more treatments before the ink is totally removed. Side effects are generally few but may include poor skin color, allergic reactions, skin sloughing, and ink darkening, according to Dr. Sonal Choudhary of the Department of Dermatology at the University of Miami.
Wrinkles: Wrinkles may be treated with lasers as well. A new technique of nonsurgical laser resurfacing has become more popular in recent years. The skin is resurfaced and smoothed, without the pain and redness that are associated with other techniques. Recovery is faster and without pain, according to the U.S. Food and Drug Administration (FDA).
Future research: Low-intensity laser therapy may stimulate the growth of bone marrow stem cells, according to one study. These stem cells may help treat a variety of diseases, such as cancer and chronic obstructive pulmonary disease (COPD). Thus, laser therapy may contribute to the new field of regenerative medicine.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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American Society for Photobiology (ASP).
American Society of Laser Medicine and Surgery, Inc. ? (ASLMS).
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Chow RT, Johnson MI, Lopes-Martins RA, et al. Efficacy of low-level laser therapy in the management of neck pain: a systemic review and meta-analysis of randomised placebo or active-treatment controlled trials. Lancet. 2009 Dec 5;374(9705):1897-908.
Higgins KM, Shah MD, Ogaick MJ, et al. Treatment of early-stage glottic cancer: meta-analysis comparison of laser excision versus radiotherapy. J Otolaryngol Head Neck Surg 2009; 38:603-612.
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Technique

General: The laser is applied to or directed toward the target area. Treatments may be as short as 10 minutes for chronic, long-lasting, or frequently recurring conditions such as pain. Treatments may be longer for more acute or severe conditions such as cancer. For conditions like pain, treatments may occur 2-3 times per week for up to 10 sessions. People with arthritis may require multiple sessions for a long period of time, possibly for months, until the pain subsides.
Laser therapy may be administered alone or in combination with medications, surgery, or both.
For surgery, the most commonly used lasers are helium-neon (HeNe) lasers and diode lasers, including gallium-aluminum-arsenium (GaAlAs) and arsenium-gallium (AsGa).
Training: Physicians who operate lasers need to undergo training courses. Specially trained nurses may aid in the control settings of lasers alongside a physician. The American Society for Laser Medicine and Surgery oversees the use of lasers by physicians. It provides documentation and training programs to teach doctors how to use lasers on patients.
There are various classes of laser product hazards recognized by the U.S. Food and Drug Administration (FDA), ranging from weakest to strongest. The strongest can impose the greatest biological damage.