What is SLT?
Selective Laser Trabeculoplasty (SLT) is a procedure designed to control intra-ocular pressure in patients with glaucoma. SLT is based on an old idea of laser treatment to the trabecular meshwork in the front of the eye. A contact lens is used with the laser to apply about 50 laser spots into the angle between the cornea and iris. This alters the way fluid flows out of the eye, and helps to lower eye pressure, thus reducing the risk of visual loss from glaucoma. The SLT is similar to Argon Laser Trabeculoplasty (ALT) which has been performed for decades in a similar fashion.
The main advantages of SLT is that it is selective and affects only the pigmented cells in the meshwork. The argon laser functions to actually burn the meshwork cells, therefore more inflammation, occasional high pressure responses, and unusual scarring of the iris are more common problems. The more selective nature of SLT also allows the procedure to be repeated on the same eye if the effect wears off in time. SLT can even be performed on eyes that have had previous eye procedures, including ALT.
All treatments for glaucoma are designed to lower IOP to a safe level to prevent the gradual deterioration of the optic nerve which leads to blindness. Eyedrops, once or twice a day, alone or in combination with other drops, are often a first-line treatment, but may not work as well as we hope to get pressure to a safe level. SLT has been effective in achieving lower pressures in many patients to avoid adding more drops, and possibly even preventing glaucoma filter surgery. Some patients achieve good control and may even be able to discontinue some drops, with cautious observation by their doctor.
What can I expect on the day of the procedure?
The laser functions in an examination room and attaches to the standard examination equipment. Once you have checked in, drops are used to numb the eye, requiring no injections or needles. A special mirrored lens, like a large contact lens, is used to focus the light rays into the angle of the eye for the treatment. Approximately 50-60 laser pulses are performed, which takes about 10 minutes. We then remove the special lens and give eye drops for inflammation and pressure. In 30 minutes, the eye pressure is tested before you leave. We usually schedule a follow up visit in one week. Patients will continue their glaucoma drops until the full pressure-lowering effect of the laser treatment is realized in a few weeks. Occasionally, we are able to discontinue some medications.
What are some risks of SLT?
It is important to maintain realistic expectations with SLT. As with other medical procedures, there are potential risks. The treatment is safe with severe complications being extremely rare. There is some chance that the procedure may not work, or may raise the eye pressure, usually a temporary response to inflammation.