Laser surgery for glaucoma uses focused beams of light to improve fluid drainage or reduce fluid production inside the eye, lowering the pressure that damages the optic nerve. Several types exist, each designed for a specific form of glaucoma. The most common, selective laser trabeculoplasty (SLT), lowers eye pressure by 18 to 40% and can serve as the very first treatment instead of daily eye drops.
How Eye Pressure Causes Damage
Glaucoma develops when fluid inside the eye doesn’t drain properly, causing pressure to build. That pressure gradually destroys nerve fibers at the back of the eye, leading to irreversible vision loss that typically starts at the edges of your visual field. Laser surgery targets this core problem: it either opens up drainage pathways so fluid can exit more freely or, in advanced cases, reduces the amount of fluid the eye produces in the first place.
Selective Laser Trabeculoplasty (SLT)
SLT is the most widely used laser procedure for open-angle glaucoma, the most common form of the disease. It works by directing short pulses of low-energy light at the eye’s drainage tissue, called the trabecular meshwork. The laser selectively targets pigmented cells in that tissue without damaging the surrounding unpigmented cells. This triggers a biological response that improves fluid outflow.
The pressure reduction is meaningful. Studies report average decreases of 18 to 40% over six to twelve months, depending on baseline pressure and whether SLT is the first treatment used. In one study of patients receiving SLT as their primary treatment, average eye pressure dropped from 25.5 to 17.9 mmHg, a 30% decrease. The procedure is performed in a clinic, takes about five to ten minutes per eye, and requires only numbing drops.
SLT as a First-Line Treatment
Traditionally, newly diagnosed patients started with daily eye drops. That thinking has shifted. The LiGHT trial, a large randomized study comparing SLT-first versus drops-first pathways, found that 74.2% of patients treated with SLT first needed no eye drops at all for at least three years. The laser-first group also had a lower rate of needing surgery down the line, comparable quality of life, and lower overall costs. Based on this evidence, SLT is now considered the most cost-effective first-line option for open-angle glaucoma and ocular hypertension.
Laser Peripheral Iridotomy (LPI)
LPI treats a different problem: angle-closure glaucoma, where the iris physically blocks the drainage channel. The laser creates a tiny hole in the outer edge of the iris, opening a new pathway for fluid to flow from behind the iris to the drainage area in front. This breaks the blockage and allows pressure to normalize.
LPI is used for acute angle-closure attacks (once the eye has been stabilized), chronic or intermittent angle-closure glaucoma, and preventively in people with narrow drainage angles who haven’t yet had an attack. It’s a quick outpatient procedure, and the opening it creates is permanent.
Argon Laser Trabeculoplasty (ALT)
ALT is an older alternative to SLT that also targets the drainage tissue, but it uses a continuous thermal laser that creates small burns. A one-year randomized trial comparing the two found no significant difference in pressure reduction: SLT lowered pressure by an average of 5.86 mmHg while ALT achieved 6.04 mmHg. Complication rates were also similar.
The key difference is what happens to the tissue. ALT causes scarring in the drainage meshwork, which limits how many times the procedure can be repeated. SLT, because it doesn’t scar the tissue, can potentially be repeated when its effect wears off. For this reason, SLT has largely replaced ALT in clinical practice.
Cyclophotocoagulation for Advanced Cases
When other treatments fail or glaucoma is too advanced for drainage-based approaches, cyclophotocoagulation takes a different strategy: it reduces the amount of fluid the eye produces by targeting the tissue responsible for making it. A newer version called micropulse transscleral cyclophotocoagulation delivers the laser energy in short bursts through the white of the eye, which is gentler on surrounding tissue than older continuous-wave methods.
Five-year data on micropulse cyclophotocoagulation shows a total pressure reduction of about 32.5%. In patients with secondary glaucoma (often representing more complex cases), average pressure dropped from 28.7 mmHg before treatment to 15.5 mmHg at five years. This approach is typically reserved for people who haven’t responded well to other options.
How Long the Effects Last
Laser treatments don’t last forever. A five-year retrospective study of SLT found that about 80% of treated eyes maintained adequate pressure control at three years, but that number dropped to roughly 61% at five years. Among eyes that did eventually need additional surgery, the average time before intervention was about 33 months, just under three years.
Even when SLT continues working, some patients need more eye drop medications over time. The average number of glaucoma medications was not significantly different at three years compared to before treatment, but by five years it had increased modestly. The practical takeaway: expect SLT to work well for several years, with the understanding that you may eventually need retreatment or supplemental drops.
Risks and Side Effects
Laser glaucoma procedures are low-risk compared to traditional surgery, but they aren’t risk-free. The most common issue is a temporary spike in eye pressure in the hours after treatment. This is well-recognized across laser procedures and is the reason your eye doctor will check your pressure before you leave the office. Anti-inflammatory drops are typically prescribed for a few days afterward to manage mild irritation.
Some patients experience temporary blurred vision, mild discomfort, or redness. Serious complications like sustained pressure elevation or significant inflammation are uncommon. Because SLT uses lower energy than ALT, it tends to produce less post-procedure inflammation, though both procedures have similar overall complication profiles in head-to-head studies.
What Recovery Looks Like
Recovery from laser glaucoma procedures is considerably easier than from traditional glaucoma surgery. Most people can read, watch TV, and use screens within a few days. Your doctor will likely adjust your eye drop regimen after the procedure, potentially stopping some glaucoma drops and adding short-term anti-inflammatory ones.
If your eye pressure runs low in the early recovery period, you may be advised to avoid heavy lifting, bending over, and vigorous exercise until it stabilizes. Most people return to light daily activities within one to two weeks. For SLT and LPI specifically, recovery is on the faster end of that range since neither procedure involves incisions or stitches. Vision typically stabilizes within days, though your doctor will monitor your pressure at follow-up visits over the coming weeks and months to confirm the treatment is working as expected.