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" is an acronym for "light amplification by stimulated emission of radiation". The ...

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 mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 perc ...

; 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. Over time, however, som ...

in favor of anti-VEGF 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 anti-VEGF 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 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 mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 perc ...

; 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, and contains connective tissues, and lies between the retina and the sclera. The human choroid is thickest at the far extreme rea ...

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 Cochrane may refer to: Places Australia *Cochrane railway station, Sydney, a railway station on the closed Ropes Creek railway line Canada * Cochrane, Alberta * Cochrane Lake, Alberta * Cochrane District, Ontario ** Cochrane, Ontario, a town wit ...

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.

Retinopathy caused by sickle cell disease

Laser coagulation has been used in people with sickle cell retinopathy. 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, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...

is administered to treat cancers like

cervical cancer Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal ...

prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that su ...

, and

colon cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowe ...

, radiation proctitis can occur, which involved chronic bleeding in the colon. Treatment with Nd:YAG lasers and with Nd:YAG laser passed through a

Potassium titanyl phosphate Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

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 by 2011, which was 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 vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal ...

, 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, vag ...

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 is widely credited with developing the predecessor of laser coagulation, photocoagulation. 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 published in 1985.

References

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