Photocoagulation Health Dictionary

Separation of the retina from the choroid in the EYE. It may be due to trauma or be secondary to tumour or in?ammation of the choroid, and causes blindness in the affected part of the retina. It can be treated surgically using PHOTOCOAGULATION.... detached retina

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

A rare malignant growth of the retina (see EYE) which occurs in infants. It can sometimes be discovered at birth because shining a light in the baby’s pupil produces a white re?ection rather than a red one. Alternatively, the infant may present with a SQUINT or a mass in the abdomen. In 25 per cent of cases there is a family history of the condition and abnormality of chromosome 13 is common (see CHROMOSOMES). It is treated by removing the eye or, if affecting both eyes, by laser PHOTOCOAGULATION with or without RADIOTHERAPY.... retinoblastoma

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

a group of conditions affecting the *macula lutea of the eye, resulting in a reduction or loss of central vision. Age-related macular degeneration (AMD, ARMD) is the most common cause of poor vision in the elderly. Two types are commonly recognized. Atrophic (or dry) AMD results from chronic choroidal ischaemia: small blood vessels of the choroid, which lies beneath the retina, become constricted, reducing the blood supply to the macula. This gives rise to degenerative changes in the retinal pigment epithelium (RPE; see retina), clinically recognized by macular pigmentation and the deposition of *drusen. Wet AMD is associated with the growth of abnormal new blood vessels underneath the retina, derived from the choroid (see neovascularization). These can leak fluid and blood beneath the retina, which further reduces the macular function. Nutritional supplements can delay the progression of AMD in some cases. Laser surgery (see photocoagulation; photodynamic therapy) and anti-VEGF therapy (see vascular endothelial growth factor) can delay progression in cases of wet AMD.... macular degeneration

(detached retina) separation of the inner nervous layer of the *retina from the outer pigmented layer (retinal pigment epithelium, RPE). It commonly occurs when a break (hole or tear) allows fluid from the vitreous cavity of the eyeball to accumulate under the retina (rhegmatogenous) but can also occur when fluid accumulates by leakage from the RPE (nonrhegmatogenous). Vision is lost in the affected part of the retina. The retina can be reattached by surgical means, such as external *plombage or internal *vitrectomy, or by creating patches of scar tissue between the retina and the choroid by application of extreme cold (see cryosurgery) or heat (see photocoagulation).... retinal detachment

n. any of various disorders of the retina resulting in impairment or loss of vision. It is usually due to damage to the blood vessels of the retina, occurring (for example) as a complication of longstanding diabetes (diabetic retinopathy), high blood pressure, or AIDS (AIDS retinopathy). In diabetic retinopathy, haemorrhaging or exudation may occur, either from damaged vessels into the retina or from new abnormal vessels (see neovascularization) into the vitreous humour. The later stages require laser treatment (see photocoagulation). In the UK all people with diabetes are screened using annual digital retinal photography. The warning signs of potentially sight-threatening retinal changes can be spotted and referral to a specialist eye clinic made for further assessment and intervention to prevent a deterioration in vision. Retinopathy of prematurity (ROP), formerly known as retrolental fibroplasia, is the abnormal growth of developing retinal blood vessels seen in premature infants. It may be mild and resolve spontaneously or severe enough to lead to blindness if untreated.... retinopathy