Laser coagulation or laser photocoagulation surgery is used to treat a number of eye diseases and has become widely used in recent decades. During the procedure, a

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

is used to finely

cauterize Cauterization (or cauterisation, or cautery) is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or ...

ocular blood vessels to attempt to bring about various therapeutic benefits. The procedure is used mostly to close blood vessels in the eye, in certain kinds of

diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease) is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries and one of the lead causes of sight loss in the wor ...

; it is no longer used in

age-related macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Some people experien ...

in favor of

anti-VEGF Anti–vascular endothelial growth factor therapy, also known as anti-VEGF () therapy or medication, is the use of medications that block vascular endothelial growth factor. This is done in the treatment of certain cancers and in age-related macu ...

drugs.

Medical uses

Diabetic retinopathy

The American Academy of Ophthalmology practice guidelines recommend laser coagulation for people who have both mild to moderate nonproliferative diabetic retinopathy (NPDR) and clinically significant macular edema outside the

fovea Fovea () (Latin for "pit"; plural foveae ) is a term in anatomy. It refers to a pit or depression in a structure. Human anatomy *Fovea centralis of the retina * Fovea buccalis or dimple * Fovea of the femoral head * Trochlear fovea of the fr ...

; treatment with

drugs is better than laser coagulation for clinically significant macular edema in the fovea. For people with severe NPDR and no macular edema, the AAO recommends laser photocoagulation for the whole retina; when there is macular edema, the laser coagulation focused on major lesions is recommended. While there is evidence that anti-

VEGF Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors ...

drugs is useful for proliferative diabetic retinopathy, laser coagulation across the whole retina is still preferred in the AAO recommendations, as there is long-term follow up data for laser treatment but not for drug treatment.

Diabetic macular edema

Anti-VEGF drugs are potentially superior to laser coagulation for

diabetic macular edema Diabetic retinopathy (also known as diabetic eye disease) is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries and one of the lead causes of sight loss in the wor ...

; some specialists are using the drugs over laser coagulation.

Macular degeneration

The American Academy of Ophthalmology practice guidelines do not recommend laser coagulation therapy for macular degeneration, but said that it may be useful in people with new blood vessels in the

choroid The choroid, also known as the choroidea or choroid coat, is a part of the uvea, the vascular layer of the eye. It contains connective tissues, and lies between the retina and the sclera. The human choroid is thickest at the far extreme rear o ...

outside of the

who do not respond to treatment with anti-VEGF drugs. Argon, krypton, dye and diode lasers have been used with varying levels of energy to try to prevent

by eliminating

drusen Drusen, from the German word for ''node'' or ''geode'' (singular, "Druse"), are tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium of the eye. The presence of a ...

. A Cochrane review published in 2015 found that while laser treatment reduces drusen, there is no difference from placebo at 2 years with respect to preventing vision loss. A 2007 Cochrane review found that laser photocoagulation of new blood vessels in the

outside of the

using blue-green argon, green argon, red krypton, or near-infrared diode is effective and economical method, but that the benefits are limited for vessels next to or below the fovea.

Retinal tears

The laser is used to create a row of microscopic burns in the target tissue to cause scarring which will prevent the edges of the tear from detaching from the layer below. Laser photocoagulation can help prevent the deterioration of some retinal disorders and reduce the risk of future vision loss, but it cannot restore vision once it has been lost. The procedure is safe and effective for treating indicated retinal disorders, such as tears and glaucoma. It is typically an outpatient procedure lasting 15 to 20 minutes. The procedure is not entirely without risk. Damage will occur to light sensitive cells of the retina cauterised by the laser which will result in some loss of vision. Light from the laser is absorbed by the retinal pigment epithelium and by the underlying choroid, which raises the temperature by 20 to 30 degrees Celsius. These thermal burns denature tissue protein, causing death of the affected retinal cells and coagulative necrosis.

Retinopathy caused by sickle cell disease

Laser coagulation has been used in people with

sickle cell retinopathy Sickle cell retinopathy can be defined as retinal changes due to blood vessel damage in the Human eye, eye of a person with a background of sickle cell disease. It can likely progress to loss of vision in late stages due to vitreous hemorrhage or r ...

. A 2015 Cochrane review found two clinical trials conducted in the 1980s using three approaches - one single-center trial employed sectoral scatter laser photocoagulation using an argon laser; and in the second, two-center trial focused on feeder vessel coagulation, one center used an argon laser and the other used a xenon arc laser. Based on weak evidence, it appears that laser coagulation may be effective in preventing visual loss and vitreous haemorrhage in this condition but that it does not have an effect on regression of proliferative sickle retinopathy or preventing the development of new vessel growth.

Radiation proctitis

When

radiation therapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a therapy, treatment using ionizing radiation, generally provided as part of treatment of cancer, cancer therapy to either kill or control the growth of malignancy, malignant cell (biology), ...

is administered to treat cancers like

cervical cancer Cervical cancer is a cancer arising from the cervix or in any layer of the wall of the cervix. It is due to the abnormal growth of cells that can invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later sympt ...

prostate cancer Prostate cancer is the neoplasm, uncontrolled growth of cells in the prostate, a gland in the male reproductive system below the bladder. Abnormal growth of the prostate tissue is usually detected through Screening (medicine), screening tests, ...

, and

colorectal cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the Colon (anatomy), colon or rectum (parts of the large intestine). Signs and symptoms may include Lower gastrointestinal ...

radiation proctitis Radiation proctitis or radiation proctopathy is a condition characterized by damage to the rectum after exposure to x-rays or other ionizing radiation as a part of radiation therapy. Radiation proctopathy may occur as acute inflammation called "acu ...

can occur, which involves chronic bleeding in the

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

. Treatment with Nd:YAG lasers and with Nd:YAG laser passed through a

Potassium titanyl phosphate Potassium titanyl phosphate (KTP) is an inorganic compound with the formula . It is a white solid. KTP is an important nonlinear optics, nonlinear optical material that is commonly used for second-harmonic generation, frequency-doubling diode-pum ...

crystal, and with an

argon laser An ion laser is a gas laser that uses an ionized gas as its lasing medium. Like other gas lasers, ion lasers feature a sealed cavity containing the laser medium and mirrors forming a Fabry–Pérot resonator. Unlike helium–neon lasers, the ...

has been studied in small clinical trials. Nd:YAG laser has been abandoned due to risks of damaging the colon wall, fibrosis, stricture formation, and recto-vaginal fistula, and severe damage in case of accidents, as well as the cost. The other two modalities were largely replaced by

argon plasma coagulation Argon plasma coagulation (APC) is a medical endoscopic procedure used to control bleeding from certain lesions in the gastrointestinal tract. It is administered during gastrointestinal endoscopy such as esophagogastroduodenoscopy or colonoscopy. ...

by 2011, which is safer and less expensive.

Complications

In the eye, side effects and complications of laser photocoagulation are not infrequent and include loss of vision, worsening

visual acuity Visual acuity (VA) commonly refers to the clarity of visual perception, vision, but technically rates an animal's ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the eye ...

, reduced night vision, and

hemorrhaging Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...

in the eye. In about 8% of cases can cause scarring which in turn can lead to permanent central vision loss.

History

German ophthalmologist,

Gerhard Meyer-Schwickerath Gerhard Rudolph Edmund Meyer-Schwickerath (10 July 1920 – 20 January 1992) was a German ophthalmologist, university lecturer and researcher. He is known as the father of light coagulation which was the predecessor to many eye surgeries. Early ...

is widely credited with developing the predecessor of laser coagulation,

photocoagulation Laser coagulation or laser photocoagulation surgery is used to treat a number of eye diseases and has become widely used in recent decades. During the procedure, a laser is used to finely cauterize ocular blood vessels to attempt to bring about v ...

. In 1946, he started conducted the first experiments on light coagulation. In 1949, he performed the first successful treatment of a retinal detachment with a light beam (light coagulation) using a self-constructed device on the roof of the ophthalmic clinic at the University of Hamburg-Eppendorf. Results of using laser coagulation to treat diabetic retinopathy were first published in 1954. Conventional macular focal and grid laser photocoagulation were established as the treatment of choice for diabetic macular edema in the Early Treatment Diabetic Retinopathy Study (ETDRS), which was published in 1985.

References

* Lawrence, Peter F; Bell, Richard M; Dayton, Merril T (2006). ''Essentials of Surgical Specialties.'' Lippincott Williams & Wilkins. {{Eye procedures Laser medicine Eye procedures