Glaucoma Laser Surgery

Several distinct laser procedures exist, each designed for a specific type of glaucoma or clinical situation. Understanding the differences can help you have a more informed discussion with your doctor about which approach is right for you.

Selective laser trabeculoplasty (SLT) is one of the most widely used laser treatments for open-angle glaucoma. It applies short, low-energy pulses to pigmented cells in the trabecular meshwork, stimulating a biological response that improves the drainage pathway without causing thermal damage to surrounding tissue. The landmark LiGHT trial demonstrated that SLT can serve as a safe and effective first-line alternative to daily eye drops. SLT typically lowers eye pressure by 20 to 30 percent, and its effects can last several years. Because SLT does not scar the tissue, it can often be repeated if the effect diminishes over time.

Argon laser trabeculoplasty (ALT) was the first laser technique developed for open-angle glaucoma. It uses a thermal laser to create small burns in the trabecular meshwork that contract the tissue and widen adjacent drainage channels. While ALT remains effective, it causes more structural changes than SLT, which limits the number of times it can be safely repeated. For this reason, SLT has largely replaced ALT as the preferred trabeculoplasty technique in clinical practice.

Laser peripheral iridotomy (LPI) is the standard treatment for narrow-angle and angle-closure forms of glaucoma. During this procedure, a focused laser creates a tiny opening in the outer edge of the iris, allowing aqueous humor to flow more freely from behind the iris to the front drainage angle. By equalizing pressure on both sides of the iris, LPI prevents the iris from bowing forward and blocking the drainage pathway. The procedure takes only a few minutes per eye and provides a permanent channel for fluid movement.

Cyclophotocoagulation (CPC) takes a different approach by targeting the ciliary body, the structure responsible for producing aqueous humor. By reducing the amount of fluid the eye generates, CPC lowers eye pressure even in patients whose drainage system is severely compromised. Traditional transscleral CPC uses continuous-wave laser energy applied through the white of the eye. Micropulse transscleral cyclophotocoagulation (MP-TSCPC) is a newer variation that delivers energy in short bursts, allowing tissue to cool between pulses and resulting in a gentler treatment with fewer side effects. CPC is frequently recommended for patients with advanced or refractory glaucoma who have not responded to other treatments.

Endoscopic cyclophotocoagulation (ECP) is performed inside the eye using a tiny camera and laser probe. The surgeon can directly visualize and treat the ciliary processes under magnification, allowing for more precise energy delivery than external approaches. ECP is often performed at the same time as cataract surgery and can provide meaningful pressure reduction with a favorable safety profile.

Most patients experience little to no pain during the procedure. Numbing drops are applied beforehand, and while you may feel a mild sensation of warmth or pressure with each laser pulse, significant discomfort is rare. Some patients describe brief stinging that lasts only a few seconds. After the procedure, mild soreness or light sensitivity may occur but usually resolves within a day.

The timeline varies by procedure. Laser peripheral iridotomy has an immediate effect on fluid flow. SLT typically reaches its full pressure-lowering potential within four to six weeks, though some improvement may be noticeable within the first week. Your follow-up appointments are designed to track how your eye pressure is responding during this period.

SLT can often be repeated because it does not cause permanent structural changes to the drainage tissue. Studies suggest that a second round of SLT can provide a similar level of pressure reduction as the initial treatment. ALT, by contrast, is generally limited to one or two sessions because it creates thermal scarring. Whether retreatment is appropriate depends on the specific procedure and your individual response.

Many patients are able to reduce the number of glaucoma medications they use after a successful laser procedure, and some are able to stop drops altogether. However, this depends on how much pressure reduction the laser achieves and what your target pressure is. Your doctor will evaluate your results at follow-up visits and adjust your medication regimen accordingly.

Candidacy depends on several factors, including your type of glaucoma, the anatomy of your drainage angle, your current eye pressure, and how well you tolerate or adhere to eye drop therapy. SLT is most commonly recommended for open-angle glaucoma, while LPI is specifically designed for narrow or closed angles. Your doctor will use diagnostic tools such as gonioscopy and OCT imaging to determine which option may be most effective for your situation.

If laser surgery does not achieve your target pressure, your doctor may recommend adding or adjusting eye drop medications, repeating the laser treatment, or considering a more involved surgical procedure such as minimally invasive glaucoma surgery (MIGS), trabeculectomy, or a tube shunt. Glaucoma management is a long-term process, and having multiple treatment options available means your care plan can evolve as needed.