Argon Laser Trabeculoplasty (ALT) or Selective Laser Trabeculoplasty (SLT)
Laser surgery has become a desirable option as an intermediate step between drugs and traditional surgery. If you have open-angle glaucoma and the disease is progressing in spite of medication, your doctor may recommend laser trabeculoplasty as an initial surgical option. Although the long-term success is variable, your doctor may suggest laser surgery if you are on more than one eye medication or if you are intolerant to particular eye drops because of an allergy or other side effects.
Your glaucoma affects the internal drainage system or trabecular meshwork of your eye, which causes an increase in intraocular pressure. Laser trabeculoplasty uses a focused beam of light to treat the drainage angle of your eye. Contrary to what you may think, laser surgery does not burn your eye or create a large hole. Instead, the laser makes subtle changes to the eye’s drainage system to make it easier for fluid to flow out of the front part of the eye. This, in turn, lowers the intraocular pressure (IOP).
What is the difference between ALT and SLT?
Selective laser trabeculoplasty (SLT) is an innovative modification of Argon laser trabeculoplasty (ALT). Both ALT and SLT are effective clinical procedures. From a patient’s point of view, you will not be able to differentiate between the two but there are a few differences in how the surgeries are performed.
ALT uses heat, whereas SLT uses a low-level laser beam and is sometimes referred to as a “cold laser.” SLT protects the trabecular meshwork (the spongy tissue around the cornea of your eye) against heat and clotting because it targets only pigmented cells and protects the surrounding area. Because it is uses a lower beam, the assumption is that SLT can be repeated if necessary. There are presently no studies that show definitive proof that one method is superior to the other. Both procedures have no systemic side effects and they are both safe, office-based procedures.
Preparing for Laser Trabeculoplasty
In preparation for the procedure, your surgeon will examine your trabecular meshwork and plan the treatment area. On the day of the surgery, eye drops will be placed in your eye both before the surgery and after to decrease the amount of fluid in your eye. This will prevent increased pressure in your eye after laser treatment.
What Happens during Laser Trabeculoplasty?
You will be given topical anesthesia (numbing drops) to numb your eye. Your surgeon will use a slit lamp microscope and lens to guide the laser beam to the trabecular meshwork where fluid drains from the eye. A total of 50 to 100 laser applications are generally administered, depending on whether a half treatment (180 degrees) or a full treatment (360 degrees) is needed. The entire process takes only about 10 minutes.
Your surgeon will administer a glaucoma drop immediately before and/or after the surgery as well as an anti-inflammatory drop to prevent post-op inflammation. About 1 to 2 hours after the procedure, your surgeon will check your eye pressure, and you will be discharged.
What Happens after Laser Trabeculoplasty?
Laser trabeculoplasty is an outpatient procedure, and you will go home the same day. However, your eyesight may be blurry, so you will need to arrange for someone to drive you home after your procedure. You should be able to resume your normal routine the day after your surgery. You may experience blurred vision and your eyes may feel irritated after the procedure but this is normal. Your doctor will prescribe anti-inflammatory eye drops to take for several days after the procedure and will schedule a post-op appointment to evaluate results of your surgery.
What are the outcomes of Laser Trabeculoplasty?
Both ALT and SLT have been proven safe and effective in lowering intraocular pressure and are equally capable of lowering eye pressure in patients with various types of open-angle glaucoma. Laser trabeculoplasty, on average, lowers eye pressure by anywhere from 5 to 7 points. The effect of the surgery will usually last somewhere between 1 to 5 years, and sometimes longer. If intraocular pressure is too high even after the procedure, your doctor can still prescribe eye drops to lower eye pressure to a safe level.
If you have primary closed-angle glaucoma, you may be a candidate for laser iridotomy. Because angle closure is on a progressive spectrum, all closed-angle glaucoma patients began with a narrow angle. Therefore, even if you have otherwise healthy eyes, a narrow angle could lead to closed-angle glaucoma.
What is Closed-Angle Glaucoma?
The angle of your eye is the location where the iris meets the sclera (white part of the eye). The internal eye liquid is called the aqueous humor, and it circulates between the iris and the lens, goes through the pupil, and then drains into the trabecular meshwork (located at the base of the cornea). When the space between the iris and sclera becomes so narrow that the space is gone completely, it is known as an angle closure.
Closed-angle glaucoma can present in many ways:
- It can be gradual and you may not experience any symptoms or obvious changes in eye pressure until intraocular pressure becomes erratic. Sometimes permanent vision loss occurs.
- It can occur all at once when IOP rises to a dangerous level. This is known as acute closure, and you may experience blurred vision, headaches, nausea or vomiting. Acute closure can rapidly result in permanent loss of vision and requires immediate treatment to break the attack.
The goal of laser iridotomy is to create a small hole in the iris to balance the pressure behind the iris and open up the angle to allow the aqueous humor to flow. Most patients respond well to laser iridotomy, but sometimes the degree of closure is so great that there is irreversible blockage. In this case, it is necessary to use glaucoma drops, cataract surgery or additional glaucoma surgeries.
Preparing for Laser Iridotomy
Your surgeon will go over all the medications that you are currently taking. You may be asked to stop taking anti-inflammatory drugs such as aspirin, as well as blood thinners such as Coumadin or Plavix. Your surgeon will advise you as to when you may resume taking your medications.
What Happens during Laser Iridotomy?
Your surgeon will administer eye drops about an hour before the procedure to make your pupil smaller, stretch your iris and keep IOP controlled during the surgery. After an hour, your surgeon will numb your eye with anesthetic, and ask you to sit at a machine that looks like a slit lamp microscope used during eye exams. As you focus on a target beam of light, your surgeon will begin the laser treatment. Many patients say they feel a slight pop when the laser is fired but say it is painless. The entire procedure takes only a few moments for each eye that needs treatment.
What Happens after Laser Iridotomy?
Laser iridotomy is an outpatient procedure and you can go home the same day, but you may need a caregiver to provide your transportation if the vision is blurred after the surgery. Most patients do not have any side effects from the surgery, but you may have some mild discomfort during the first few days. Your doctor will prescribe anti-inflammatory drops for about a week following the surgery.
There are no restrictions after surgery and you can resume normal activities. In most cases, laser iridotomy is sufficient to open the narrowed or closed angle. A small percentage of patients may need additional treatment called iridoplasty or they may need cataract surgery or glaucoma filtering surgery.
Talk to your doctor about what type of laser procedure would help your glaucoma. Contact a treatment center near you to schedule a consultation.