Glaucoma is a progressive eye condition that causes damage to the optic nerve, often due to elevated pressure inside the eye, known as intraocular pressure (IOP). This pressure buildup occurs when the fluid inside the eye, called aqueous humor, cannot drain properly through the eye’s natural drainage system. To protect the optic nerve and prevent irreversible vision loss, the primary treatment goal is to lower this internal pressure. Laser surgery represents a common, minimally invasive option used to manage glaucoma by improving the fluid outflow from the eye.
Defining Laser Treatment Options
The most common laser procedures for open-angle glaucoma are Selective Laser Trabeculoplasty (SLT) and Argon Laser Trabeculoplasty (ALT). Both target the trabecular meshwork, the spongy tissue in the eye’s drainage angle, to increase the outflow of fluid and reduce the IOP.
Selective Laser Trabeculoplasty (SLT) uses a low-energy laser to target specific pigmented cells within the trabecular meshwork without causing widespread thermal damage. This selective targeting stimulates a biological response that restructures the drainage system, making it function more efficiently. Because SLT is gentler and does not cause scarring, it is often preferred and can be repeated if the initial effect wears off.
ALT is an older technique that uses a thermal laser to create small, controlled burns. While effective at improving fluid outflow, the thermal energy causes tissue scarring and coagulation. This damage generally limits ALT to a one-time treatment, as repeat procedures are often not possible. For angle-closure glaucoma, Laser Peripheral Iridotomy (LPI) is used to create a tiny hole in the iris, allowing fluid to flow more freely and relieve pressure spikes.
Measuring Success and Effectiveness
Laser trabeculoplasty procedures are designed to lower IOP to a target level that prevents further optic nerve damage. Success is defined as achieving a significant IOP reduction, typically between 20% to 30% from the baseline pressure. For many patients, this reduction is sufficient to avoid the need for daily medication drops or more invasive incisional surgery.
The pressure-lowering effect varies, but SLT commonly lasts between one and five years. Studies have shown that SLT can safely provide drop-free IOP control and is as effective as topical medication in controlling IOP. This durability and effectiveness have led major organizations to list SLT as an initial treatment option for open-angle glaucoma.
The ability to repeat SLT when the effect diminishes makes it a flexible and sustainable strategy, unlike ALT, which is generally a one-time option. The procedure is considered successful if it delays the need for more complex surgical intervention and maintains stable eye pressure.
Immediate and Long-Term Complications
The safety of laser surgery is high, with complications generally being mild and temporary. Immediately following the procedure, patients may experience transient side effects such as mild eye irritation, redness, or inflammation. These symptoms are typically managed with anti-inflammatory eye drops for a few days and resolve quickly.
A more specific immediate risk is a temporary spike in intraocular pressure (IOP). This increase occurs in a small percentage of patients, usually within the first few hours after treatment. The spike is managed with pressure-lowering eye drops and is a primary reason patients are monitored shortly after the procedure.
Long-term risks are minimal, though the primary limitation is the procedure’s lack of permanence. The effect of the laser treatment wears off over time, necessitating a repeat procedure, a return to medication, or progression to incisional surgery. In rare instances, accelerated cataract development, corneal edema, or long-term inflammation have been reported. Permanent vision loss is extremely uncommon.
Patient Selection and Suitability
Determining the suitability of laser surgery is essential for ensuring the procedure is safe and effective. The ideal candidate typically has open-angle glaucoma or ocular hypertension. Patients who struggle with the consistent use of daily eye drops or experience negative side effects from medication are particularly good candidates for laser treatment.
Laser surgery is often less suitable in certain situations. Patients with narrow-angle or angle-closure glaucoma may require a different laser procedure, such as LPI, rather than trabeculoplasty. Additionally, patients with severe corneal issues or advanced-stage glaucoma requiring an immediate, substantial pressure drop may need to proceed directly to traditional incisional surgery. The best responses to SLT are often seen in patients with higher baseline IOP.