Excimer laser Health Dictionary

Laser stands for Light Ampli?cation by Stimulated Emission of Radiation. The light produced by a laser is of a single wavelength and all the waves are in phase with each other, allowing a very high level of energy to be projected as a parallel beam or focused on to a small spot.

Various gases, liquids and solids will emit light when they are suitably stimulated. A gassed laser is pumped by the ionising e?ect of a high-voltage current. This is the same process as that used in a ?uorescent tube. Each type of laser has a di?erent e?ect on biological tissues and this is related to the wavelength of the light produced. The wavelength determines the degree of energy absorption by di?erent tissues, and because of this, di?erent lasers are needed for di?erent tasks. The argon laser produces light in the visible green wavelength which is selectively absorbed by HAEMOGLOBIN. It heats and coagulates (see COAGULATION) tissues so can be used to seal bleeding blood vessels and to selectively destroy pigmented lesions. The carbon-dioxide laser is the standard laser for cutting tissue: the infra-red beam it produces is strongly absorbed by water and so vaporises cells. Thus, by moving a ?nely focused beam across the tissue, it is possible to make an incision.

The two main uses of laser in surgery are the endoscopic (see ENDOSCOPE) photocoagulation of bleeding vessels, and the incision of tissue. Lasers have important applications in OPHTHALMOLOGY in the treatment of such disorders as detachment of the retina and the diabetic complications of proliferative retinopathy and of the cornea (see EYE, DISORDERS OF). The destruction of abnormal cells – a sign of pre-malignancy – in the CERVIX UTERI is done using lasers. The beams may also be used to remove scar tissue from the FALLOPIAN TUBES resulting from infection, thus unblocking the tubes and improving the chances of CONCEPTION. Lasers also have several important applications in DERMATOLOGY. They are used in the treatment of pigmented lesions such as LENTIGO, in the obliteration of port-wine stains, in the removal of small, benign tumours such as verrucas, and ?nally in the removal of tattoos.

Low-intensity laser beams promote tissue healing and reduce in?ammation, pain and swelling. Their e?ect is achieved by stimulating blood and lymph ?ow and by cutting the production of PROSTAGLANDINS, which provoke in?ammation and pain. The beams are used to treat ligament sprains, muscle tears and in?amed joints and tendons.

The three great advantages of lasers are their potency, their speed of action, and the ability to focus on an extremely small area. For these reasons they are widely used, and have allowed great advances to be made in microsurgery, and particularly in FIBREOPTIC ENDOSCOPY.... laser

Use of a laser beam in a variety of medical procedures. Highintensity laser beams cut through tissue and cause blood clotting. They can be used in surgery and to destroy abnormal blood vessels. Lasers are frequently used in ophthalmology to treat eye disorders, in gynaecology (for example, to unblock fallopian tubes), and to remove birthmarks and tattoos.... laser treatment

a type of *laser that utilizes argon gas to produce a beam of intense light, used especially in eye surgery to treat disease of the retina (e.g. diabetic retinopathy) or glaucoma (as in argon laser *trabeculoplasty). See also photocoagulation.... argon laser

a type of laser whose medical uses include treating diseases of the retina, by producing small burns in the retina (see photocoagulation), and selected cases of glaucoma (cyclophotocoagulation). It is also used for treating varicose veins (see endovenous laser treatment).... diode laser

(EVLT) a minimally invasive procedure to treat *varicose veins. A laser fibre (usually an 810-nm *diode laser) contained within a sheath is fed into the vein by ultrasound guidance and slowly withdrawn as it is fired, thereby delivering laser energy that causes irreversible destruction and eventual ablation of the vein.... endovenous laser treatment

a laser that emits optical pulses with a duration of femtoseconds (fs; 1 fs = 10?15 s), allowing micrometer-level accuracy and needle– or blade-free surgery. It has the potential to carry out lens extraction or cataract surgery through a pin-prick incision.... femtosecond laser

a type of *YAG laser that uses a short-pulsed high-energy beam with a wavelength of 2100 nm to cut, perforate, and fragment tissue. It has a penetration of 0.4 mm. This laser is used in the fragmentation of urinary tract calculi (stones) and in *enucleation of the prostate gland.... holmium:yag laser

(LAUP) laser surgery to the palate, which is used in the treatment of *obstructive sleep apnoea.... laser-assisted uvulopalatoplasty

a non-invasive instrument for measuring blood flow through tissue (e.g. skin) utilizing a laser beam.... laser doppler flowmeter

see ophthalmoscope.... scanning laser ophthalmoscope

(SLT) see trabeculoplasty.... selective laser trabeculoplasty

a type of *laser whose active medium is a crystal of yttrium, aluminium, and garnet. It is used for cutting tissue, for example in lens *capsulotomy or *iridotomy. Specialized types (e.g. the *holmium:YAG laser) are used for various specific purposes....  yag laser