Selective Laser Trabeculoplasty (SLT) is a non-invasive, outpatient procedure used to manage open-angle glaucoma. It uses a specialized laser to safely reduce high intraocular pressure (IOP), the primary risk factor for vision loss in glaucoma. SLT improves the outflow of fluid by addressing the eye’s natural drainage system. It is often used as a first-line treatment or as an alternative to daily eye drops, achieving pressure reduction without causing thermal damage or scarring to the eye’s tissues.
Targeting the Trabecular Meshwork
The effectiveness of Selective Laser Trabeculoplasty lies in its precise interaction with the trabecular meshwork. This meshwork is a spongy tissue located where the iris meets the cornea, and its function is to filter the aqueous humor, the fluid that nourishes the eye’s internal structures. In open-angle glaucoma, this meshwork becomes less efficient, causing the fluid to back up and the eye pressure to rise.
SLT is considered “selective” because it employs low-energy light pulses that target only the pigmented cells within the meshwork tissue. The laser’s short pulse duration and specific wavelength allow the pigmented cells to absorb the energy, while the surrounding, non-pigmented tissue remains unaffected. This selectivity avoids the thermal damage and scarring associated with older laser treatments, making the procedure repeatable.
The stimulation of these targeted cells triggers a natural biological response within the trabecular meshwork. This response involves the release of chemicals that promote cellular remodeling and cleansing of the drainage channels. This leads to an increased rate of aqueous humor outflow, which subsequently lowers the intraocular pressure to a safer level.
The SLT Appointment Experience
The entire Selective Laser Trabeculoplasty appointment is typically an in-office procedure, often taking less than an hour from start to finish. Preparation begins with anesthetic eye drops to numb the eye’s surface, ensuring comfort. Other drops, such as a topical alpha-agonist, may be applied beforehand to help prevent a temporary spike in eye pressure that can sometimes occur immediately after the laser treatment.
The patient sits at a specialized laser machine that looks very similar to the standard microscope used for a routine eye examination. The eye care professional then places a special contact lens directly onto the eye’s surface. This lens helps to keep the eyelid open, stabilize the eye, and allows the practitioner to visualize and focus the laser beam precisely onto the trabecular meshwork.
During the actual laser application, the patient may see bright flashes of light and hear a series of clicking sounds as the laser fires. The procedure itself is generally painless, though some patients report a mild sensation of pressure or a slight ache inside the eye. The laser treatment portion is very brief, often lasting only five to ten minutes per eye, allowing the patient to return home shortly after the session is complete.
Recovery and Pressure Monitoring
Following the procedure, the eye is checked, often within an hour, to monitor the initial intraocular pressure. Patients are advised not to drive themselves home due to temporary blurring of vision caused by the contact lens gel and the procedure itself. Common side effects include a gritty sensation, mild redness, or light sensitivity, which usually resolve within a day or two.
A prescription for anti-inflammatory eye drops is often given to manage any mild inflammation that arises from the laser stimulation. The full pressure-lowering effect is not immediate, as it relies on the body’s biological remodeling process. The pressure reduction is gradual, typically taking between one to three months to reach its maximum effectiveness.
Regular follow-up appointments are scheduled, usually within two to four weeks, to accurately assess the sustained drop in intraocular pressure. The treatment’s effect can last anywhere from one to five years, though the benefits may sometimes last longer. Because the procedure is non-destructive, it can be safely repeated if the pressure begins to rise again in the future, providing a flexible, long-term management option for glaucoma.