Glaucoma is a series of diseases that if left untreated can cause damage to the optic nerve resulting in gradual vision loss and eventual blindness. Damage to the optic nerve, due to glaucoma, is usually caused by an elevated intraocular pressure (IOP).
A clear fluid, called aqueous humor, fills the front of the eye (anterior chamber) and provides nourishment to the tissues. Like the air in a balloon, the aqueous also provides pressure to help maintain the shape of the eye.
Open Angle Glaucoma
Open Angle Glaucoma (OAG), the most common type of glaucoma, occurs when there is either a sustained increase in fluid production or a decrease in fluid drainage. With this imbalance in fluid flow, there is an increase in the intraocular pressure, which in turn reduces blood flow to the sensitive tissues of the optic nerve. Over time, as the optic nerve fibers are destroyed, peripheral (side) vision lost.
Treatment of Open Angle Glaucoma
OAG treatment concentrates on lowering the pressure inside the eye to prevent damage to the optic nerve, the most common treatments for glaucoma have been the use of medications in the form of eye drops or pills, and laser treatments.
Laser treatments and some medications allow for faster drainage, while other medications reduce the production of aqueous humor. If these methods fail to decrease fluid pressure, surgery may be required to create a new drainage channel.
Traditional Laser Treatment
Since medications and eye drops can cause undesirable side effects or simply fail to control glaucoma, and because patients frequently fail to take their medications, laser therapy may be a better alternative. With traditional argon laser trabeculoplasty (ALT), tiny, evenly spaced burns are made in the trabecular meshwork with an argon laser. These laser burns facilitate the drainage of aqueous humor. However, scarring of the trabecular meshwork occurs as a result of ALT burns, and may limit its success and the ability to retreat the eye in the future, should the procedure need to be repeated.
Selective Laser Trabeculoplasty (SLT)
Selective Laser Trabeculoplasty (SLT) is an advanced type of laser treatment to manage patients with open-angle glaucoma. Instead of generally burning tissue as in ALT, SLT selectively simulates or changes only specific pigmented cells to activate increased fluid drainage. Both SLT and ALT produce equivalent drops in IOP, however the more gentler SLT procedure does not have the associated damage to other tissues and adverse scarring effects. For this reason, where ALT is limited, SLT may potentially be repeated. SLT has also been found to be effective when ALT and other forms of medical treatment have failed.
Benefits of SLT
SLT results in a biological response that increases aqueous drainage, and reduces intraocular pressure without burning tissue.
No adverse reactions from medications.
No adverse scarring of trabecular meshwork.
May reduce the need for lifelong use of expensive eye drops and other medications.
May reduce or eliminate the trouble of always having to take glaucoma medications.
A recent study1 published in the Journal of Glaucoma found that there was no difference in the reduction of eye pressure after SLT compared to that of medicated eye drops when used as a first-line treatment for glaucoma.
How SLT is Performed
SLT is usually performed in the office and only takes about 5 minutes. Prior to the procedure, eye drops will be given to prepare the eye for treatment. The laser applications are made through a special microscope, similar to the one used for eye examinations. About 1-2 hours of office time should be planned (depending on the treating physician) so eye pressure can be checked after the eye is treated.
What should be expected after SLT treatment?
The doctor may treat the eye with anti-inflammatory eye drops that will be continued for 4 to 7 days after the procedure. Most patients will have to return for follow-up visits to re-check the treated eye. Unlike some glaucoma medication, there are no incidences of allergy or systemic side effects with SLT. Complications are minimal but may include inflammation, temporary increase in IOP, conjunctivitis, or eye pain. For more information about SLT and how it may benefit you, please ask your treating physician.
Prevention is the Best Medicine
Vision loss from glaucoma is permanent but can usually be prevented with early detection and treatment. Glaucoma management is usually a lifelong process that requires frequent monitoring and constant treatment. Since there is no way to determine if glaucoma is under control based on how a person feels, a person with glaucoma generally should be examined every 3 to 4 months. If you have experienced a loss of peripheral vision or are having other difficulties with your vision, you should have a complete eye examination.
1 Reference: Katz LJ, et al. J Glaucoma. 2012:doi:10.197/ITG.0b013e318218287f