Laser trabeculoplasty is an in-office eye procedure that lowers eye pressure in people with glaucoma by improving the eye’s natural drainage system. It works by directing short pulses of laser light at the trabecular meshwork, a ring of spongy tissue inside the eye where fluid drains out. The procedure takes about 5 to 10 minutes per eye and typically reduces eye pressure by 10 to 25 percent, enough to slow or prevent the optic nerve damage that causes vision loss in glaucoma.
How It Lowers Eye Pressure
Your eye constantly produces a clear fluid called aqueous humor that nourishes the front of the eye and then drains out through the trabecular meshwork. In open-angle glaucoma, this meshwork becomes less efficient at draining fluid, so pressure builds up inside the eye. Laser trabeculoplasty targets this meshwork directly.
The laser doesn’t simply burn a hole for fluid to escape. Instead, it triggers a biological remodeling process. The laser energy stimulates the tissue to release signaling molecules that recruit immune cells to the area, break down clogged material in the meshwork, and promote new cell growth. Over a period of weeks, this remodeling opens up the drainage pathways and allows fluid to flow out more freely, bringing eye pressure down.
SLT vs. ALT: Two Types of Laser
The two main types are selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT). SLT is the version used in the vast majority of cases today, and for good reason: it’s far gentler on the tissue.
When researchers compared the two lasers on human eye tissue, ALT created visible craters in the meshwork, with destruction of the structural fibers, cell death, and debris scattered through the treatment zone. SLT, by contrast, showed no structural damage to the meshwork’s framework. The only signs of laser interaction were cracking of pigment granules inside cells and minor disruption of the surface cell layer.
This difference matters because less tissue damage means SLT can be safely repeated when the effect wears off. ALT leaves permanent scarring that limits how many times it can be performed. For this reason, SLT has largely replaced ALT as the standard approach.
Who Is a Good Candidate
Laser trabeculoplasty works best for people with open-angle glaucoma, the most common form. It’s a strong option if your eye pressure isn’t reaching its target despite daily eye drops, if you have trouble remembering or tolerating your drops, or if you experience side effects from glaucoma medications. It’s also used for two specific subtypes of glaucoma (pseudoexfoliation and pigmentary glaucoma) that tend to respond well because the trabecular meshwork in these conditions has extra pigment for the laser to target.
The procedure is not appropriate for everyone. It should be avoided in inflammatory types of glaucoma, since the laser-induced inflammation can cause dangerous pressure spikes. It’s also not recommended for advanced glaucoma where the optic nerve is severely damaged, because even a temporary pressure spike during recovery could cause further harm. And if scar tissue blocks the doctor’s view of the trabecular meshwork, the laser simply can’t reach its target.
What the Procedure Feels Like
The entire visit takes several hours, but the laser treatment itself lasts only about 5 to 10 minutes. You’ll sit at a device that looks similar to the equipment used during a routine eye exam. A numbing drop is placed in your eye, and then the doctor rests a small lens directly on the eye’s surface. This lens magnifies the drainage angle and keeps your eye steady.
As the laser fires, you may feel a mild prickling or tingling sensation. The doctor adjusts the laser power based on how the tissue responds and can reduce it if you’re uncomfortable. Once the treatment is finished, the lens is removed and your eye is rinsed. You’ll then wait 30 minutes to an hour while the staff rechecks your eye pressure to make sure it hasn’t spiked.
Right after treatment, your eye may feel sore or swollen, and your vision can be blurry or light-sensitive. These effects usually clear substantially during that recovery window. Most people are able to drive themselves home afterward. You’ll typically use anti-inflammatory eye drops for about a week.
How Well It Works
Results vary from person to person. In studies tracking patients over three months, about 68 percent of treated eyes achieved at least some pressure reduction, while roughly 24 percent saw a drop of 30 percent or more. The average reduction at three months was about 12 percent of the starting pressure. That may sound modest, but even small, sustained pressure reductions meaningfully slow glaucoma progression over years.
Not everyone responds. Around 10 percent of patients see no change at all, and a small number experience a slight increase in pressure. Your doctor will typically assess the results at follow-up visits over several weeks. If the response is insufficient, continuing or adjusting eye drop medications remains an option.
How Long the Effect Lasts
The pressure-lowering effect of SLT is not permanent. Studies following patients long-term found that the effect typically wanes over roughly two years. In one study, the average time before patients needed retreatment was about 26 months. At the 24-month mark, only about 36 percent of initially treated eyes still maintained a pressure reduction greater than 20 percent.
The good news is that SLT can be repeated. Because it causes minimal structural damage to the trabecular meshwork, a second round of treatment is feasible when the first wears off. Repeat SLT has been shown to produce meaningful pressure reductions for at least another 24 months, though the percentage of patients achieving strong results does decline somewhat compared to the first treatment (29 percent achieving greater than 20 percent reduction versus 36 percent initially).
Risks and Side Effects
Laser trabeculoplasty is considered a low-risk procedure, but it does have predictable side effects. The most common is a temporary spike in eye pressure, which occurs in up to 28 percent of patients. These spikes almost always happen within 24 hours and are typically managed the same day, either with pressure-lowering drops given in the office or with a brief observation period. Eyes with more heavily pigmented trabecular meshwork are more likely to experience larger spikes.
Mild inflammation in the eye is the other common side effect, which is why anti-inflammatory drops are prescribed for the first week. Uncommon complications include minor bleeding inside the eye, fluid buildup behind the eye or in the retina, corneal cloudiness, and temporary changes in glasses prescription. Serious, vision-threatening complications are rare.
Laser vs. Eye Drops: Cost and Convenience
One of the biggest practical advantages of laser trabeculoplasty is that it can reduce or eliminate the need for daily eye drops, at least for a period of time. Glaucoma drops are a lifelong commitment with ongoing costs, and many people struggle with the daily routine. Missed doses are one of the most common reasons glaucoma worsens.
Cost-effectiveness research has found that SLT and daily medications produce similar pressure reductions, but SLT tends to be the more economical choice over time. One analysis found that the annual cost per patient was essentially equivalent between the two approaches when the upfront procedure cost was factored in, but SLT had a slight edge in both effectiveness and cost. The real savings grow over multiple years, since a single treatment replaces months of daily drop purchases, pharmacy visits, and the hidden costs of managing medication side effects.
For these reasons, many eye specialists now offer SLT as a first-line treatment for newly diagnosed open-angle glaucoma, not just as a backup when drops fail. The choice between starting with laser or starting with drops is a conversation worth having with your ophthalmologist, since both are considered effective initial approaches.