Lasers used in the treatment of Glaucoma
There are two main types of lasers used in the treatment of glaucoma:
Selective laser trabeculoplasty (SLT)
Laser iridotomy for prevention of angle closure glaucoma
Laser iridotomy is an office procedure in which a microscopic hole is created in the periphery of the iris (the blue/brown coloured part of the eye). The procedure is usually done in eyes where there is "angle closure glaucoma" or a risk of of that condition. The procedure usually takes a few minutes and causes brief and minimal discomfort, if any. The procedure is often done to prevent the sudden onset of a glaucoma attack, where the eye may rapidly become blurry and painful. Acute glaucoma is a medical emergency, and is specifically a risk in patients with a shallow anterior chamber. A shallow chamber and a risk of angle closure glaucoma do not usually cause symptoms in the early stages, but they are visible on detailed eye examination. These risky features are often found during a routine eye examination for other reason, by an optometrist or an ophthalmologist.
Laser iridotomy also has an important role in chronic angle closure glaucoma management and in a few other, less common conditions.
The result of laser iridotomy is a safer anatomical configuration in the eye. The procedure is not usually meant to reduce the eye pressure, but to prevent a sudden, dangerous rise in the pressure. Similarly, the laser is not expected to improve or change the vision in any significant way.
SLT laser for treatment of open angle glaucoma
Selective laser trabeculoplasty (SLT) is a laser procedure meant to reduce the pressure inside the eye. It is a common treatment for eyes with open angle glaucoma. Open angle glaucoma is more common than angle closure glaucoma.
SLT works by delivering laser pulses to the area of the eye that controls the intraocular pressure. That area is called the trabecular meshwork. It works like a fluid filter works. It is responsible for the normal drainage of the internal fluid of the eye, which has to exit the eye through the trabecular meshwork. The more efficiently the trabecular meshwork works, the lower the fluid pressure inside the eye is.
SLT works by stimulating biologic changes in the trabecular meshwork and, as a result, reducing the eye pressure. The treatment is usually done in 1-2 sessions per eye. It is usually painless and takes a few minutes. While it is a very safe treatment, it is not always successful in reducing the eye pressure. However, if it succeeds it may improve the control of glaucoma significantly. In some patients it may then substitute eyedrop treatment. Successful SLT may have to be repeated after some time, typically years, if the effect wears off with time.
The effect of SLT may take a few weeks, as it depends on a slow biological process that is expected to happen in the eye after the treatment.
SLT does not improve the eyesight. Whether it is successful can only be determined by measuring the intraocular pressure after the procedure.