Selective laser trabeculoplasty (SLT)

What is selective laser trabeculoplasty (SLT)?

Selective laser trabeculoplasty is a laser surgery to lower intraocular pressure in people with open-angle glaucoma. This outpatient procedure may be a first-line treatment or performed when someone is already on medications but still has high eye pressure. 

When the pressure in the eye is too high, it can damage the optic nerve, which transfers light signals from the eye to the brain. Over time, the damage can lead to glaucoma and vision loss. Open-angle glaucoma is the most common type of glaucoma. High intraocular pressure (IOP)—the pressure inside the eye—is a major risk factor.

Studies have found that SLT can be as effective at reducing eye pressure as some glaucoma medications. It can help lower eye pressure by 20%-30% and is effective for about 80% of patients. Whether glaucoma eye drops are still needed after the surgery varies with each individual.

Although the pressure-lowering effect wears off after a few years, the procedure can be repeated. SLT does not affect eligibility for other surgical or medical treatments.

READ MORE: Glaucoma: Types, causes, symptoms and treatment

How does selective laser trabeculoplasty (SLT) work?

Selective laser trabeculoplasty helps decrease IOP by improving fluid drainage in the eye.

In open-angle glaucoma, the nourishing fluid—the aqueous humor—in the eye's front chamber cannot properly drain through a tissue called the trabecular meshwork. 

When aqueous humor production is balanced with drainage, the eye's pressure remains in the normal range. When this fluid cannot drain well through the trabecular meshwork, the backup causes chronically high IOP. 

An ophthalmologist performs SLT with a laser to increase the outflow of aqueous humor through the trabecular meshwork. This laser treatment is "selective." It targets only pigmented cells in the trabecular meshwork. It leaves other tissues unharmed. This means that the treatment can be safely repeated if necessary.

What to expect during SLT

SLT is an outpatient procedure. Eye drops are given before and after to numb the eye and keep the pressure down. It typically takes five to 10 minutes and is essentially painless.

1. An eye drop that helps prevent a rise in eye pressure is placed in the eye (typically apraclonidine). 

2. An anesthetic eye drop is used to numb the eye.

3. A clear, cushioning gel is put on the eye. 

4. A contact lens is placed over the gel to help focus the low-energy laser on the trabecular meshwork. The lens also prevents blinking and keeps the eye from moving during the procedure. 

5. A laser will be focused on the trabecular meshwork in a series of pulses. Clicks and flashes of light may occur while the laser is used. The doctor may slowly rotate the lens as they treat different areas of the trabecular meshwork. 

When the procedure is finished, the lens will be removed. The gel may take about an hour to clear from the eyes. You may also get anti-inflammatory eye drops to use for several days.

Your IOP will be checked after an hour to ensure it has not risen too much. If it isn’t elevated, you will be able to go home. You will be asked to schedule a follow-up appointment at one to two weeks, four to six weeks and then every three to four months. 

After the procedure, you will need someone to drive you home. You should not exert yourself the rest of the day. You may resume normal activities the following day. There are no visual restrictions. If you experience slight discomfort, you can take Tylenol as recommended by your doctor. If discomfort is severe or vision suddenly worsens, contact your doctor immediately.

READ MORE: What are my options for glaucoma surgery?

Benefits and risks of SLT

SLT helps prevent further vision loss by lowering intraocular pressure. But it cannot recover lost vision, so it is very important to take your glaucoma medications and go to follow-up appointments.

Benefits

Laser trabeculoplasty is able to be performed in the office instead of an operating room. No needles or injections are used during the procedure. 

Studies have shown that laser treatment for open-angle glaucoma is possibly more cost-effective than medication. This is because laser treatment is a one-time upfront cost, while medication costs accumulate over time.

Risks and complications

Laser trabeculoplasty does not usually have many complications. However, some side effects and complications that patients may experience include:

• Eye discomfort

• Blurry vision

• Inflammation

• Blockage of the drainage angle

Eye pressure may temporarily get higher after the procedure. However, these symptoms usually resolve within a few hours to a few days by themselves or with medication.

If high IOP continues after the procedure, your doctor will recommend additional treatment. Note that even if someone experiences a temporary increase in IOP immediately after treatment, they can still have a long-term reduction in IOP. 

What is the success rate of SLT?

SLT is typically an effective procedure for reducing IOP for a period of time. One study analyzed the success rate of SLT surgery, defining success as a reduction of IOP of 3 mm Hg. Normal eye pressure averages range from 12-21 mm Hg.

The study found that SLT lowers IOP, but its effect decreases over time. However, SLT can be safely repeated. 

• At year 1, the success rate was 68%

• At year 2, the success rate was 46%

• At year 3, the success rate was 32%

Since the response to the surgery varies, some people will need to keep taking glaucoma medicine after SLT to keep their IOP in the normal range. 

SLT vs. other laser treatments for glaucoma

A laser can be used to perform several types of outpatient glaucoma surgeries. These include argon laser trabeculoplasty (ALT) and laser peripheral iridotomy (LPI).

Argon laser trabeculoplasty (ALT)

Argon laser trabeculoplasty is an outpatient laser procedure that uses a high-energy laser rather than a low-energy laser. ALT is not usually recommended as a first-line treatment because it creates more scar tissue, making it less effective when repeated. 

READ MORE: Argon laser trabeculoplasty (ALT) for Glaucoma

Laser peripheral iridotomy (LPI)

This outpatient laser procedure treats or prevents narrow-angle glaucoma or closed-angle glaucoma, which is less common than open-angle glaucoma. Narrow-angle glaucoma needs a different laser procedure than open-angle glaucoma. The meshwork functions properly in narrow-angle glaucoma, but the drainage area has narrowed. This angle can close and cause an acute angle-closure attack, resulting in a sudden increase in eye pressure. LPI makes a small hole in the eye's iris, allowing fluid to flow through it.

When doctors recommend SLT over medication or surgery

SLT provides a treatment option for people who do not respond to glaucoma drops. It may also be an option if they cannot take them due to allergies or other side effects.

Some people with difficulty remembering their glaucoma drops daily may benefit from the surgery. This can be especially helpful for older patients. Routine follow-up appointments will still be needed because the treatment can lose its effect over time.

SLT as a first-line treatment for glaucoma

The LiGHT trial was a study that looked at how effective SLT was as a glaucoma treatment compared to medication. It demonstrated that SLT is a reasonable choice as a first-line treatment for glaucoma. It also found that laser treatment is at least as good as medication in controlling the disease in the long term and may even be better. The study also found that fewer surgeries were needed in the eyes that received laser treatment as a first-line treatment.

If you have additional questions or concerns about open-angle glaucoma and SLT, contact your eye doctor's office. They can help you understand treatment options for your specific condition. 

READ MORE: Types of eye surgery and the conditions they treat

Page published on Friday, July 12, 2024

Page updated on Tuesday, July 16, 2024