Trabeculoplasty is a laser glaucoma treatment that is becoming increasingly popular. While trabeculoplasty is not the preferred method of glaucoma treatment for all individuals, it can be used in certain situations to help lower eye pressure in lieu or in combination with eyedrops.
Glaucoma
Glaucoma is a disease of the optic nerve in which, over time, axons of the optic nerve are compressed and die off, leading to permanent vision loss.
There are many different variations of glaucoma. In some cases, an individual’s eye pressure may be elevated resulting in excess pressure compressing the optic nerve, hence leading to optic nerve damage and cell death.
The objective of glaucoma treatment, therefore, is to try and preserve the optic nerve by lowering eye pressures and relive any extra pressure from compressing the nerve.
Historically this has been accomplished via eye drops. More recently, a laser surgery called Laser Trabeculoplasty has been offering glaucoma patients an alternative to eyedrops.
To best understand the treatment, it is best to have a basic understanding of eye pressure.
Anatomy of Eye Pressure
Eye pressure is determined by the amount of fluid there is in the anterior half of the eye.
This fluid is called aqueous humor. It is produced through filtration of the blood to provide nutrients and oxygen to the anterior structures of the eye.
Aqueous humor is created by the ciliary processes of the ciliary muscle at the equator of the eye.
The aqueous humor then travels around the lens of the eye and down into the periphery of the inner eye where it then drains out of the eye through a structure called the trabecular meshwork.
The amount of aqueous humor within the anterior chamber of the eye at any given time is what creates eye pressure.
Normal eye pressures run between 12-22 mmHg.
When people have elevated eye pressures, it can be a result of either a production issue (too much blood filtration by the ciliary processes) or a drainage issue (possible clogging or narrowed channels within the trabecular meshwork)—or a combination of both!
Different eyedrops focus on decreasing aqueous production or increasing the outflow through the trabecular meshwork.
Laser Trabeculoplasty
The objective of the laser trabeculoplasty is to use a laser to increase the area in which aqueous can drain through altering the structural integrity of the trabecular meshwork.
There are two different ways to perform this procedure—one is done using an Argon Laser (ALT) whereas the other utilizes a Selective Laser (SLT).
In ALT, an ophthalmologist uses an Argon laser and a special mirror lens to focus the light on the trabecular meshwork of the eye.
The laser emits light to structurally shrink the collagen fibrils of the trabecular meshwork, which enlarges the spaces of the trabecular meshwork, creating greater opportunity for aqueous humor outflow.
This process creates coagulative damage to the trabecular meshwork during the process. Therefore, the treatment area only involves 180 degrees of the total 360 degrees of the trabecular meshwork to ensure the eye is not overwhelmed during the procedure.
Each time the laser is applied to the trabecular meshwork, it creates a small hole about 50 micrometers in size. The process is repeated about 50 times to create the 180 degree treatment area. Often, a second surgery is required to treat the other 180 degrees of the meshwork.
On average, this procedure lowers intraocular pressure by about 6 mmHg.
In SLT a YAG laser is used in a similar fashion, but does not cause physical structural damage to the trabecular meshwork. Instead, the laser stimulates an immune response which ramps up the activity level of the trabecular meshwork cells themselves to increase aqueous outflow.
In other words, ALT “opens the drain” and SLT “stimulates the cells” to make them more effective in aqueous humor drainage.
The treatment of an SLT involves creating small holes 400 micrometers in size. The process is repeated 90-120 times to create a treatment area involving 360 degrees of the trabecular meshwork—thus the entire trabecular meshwork can be treated in one setting.
On average, SLT lowers intraocular pressure by about 5.8 mmHg.
Neither procedure is particularly painful—the laser may stimulate mild discomfort but does not hurt.
If you think you may be interested in trabeculoplasty to help manage your glaucoma, speak with your eye doctor to see if he or she thinks you may be a good candidate.
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