Selective Laser Trabeculoplasty (SLT)

How SLT works

The laser targets pigmented cells in the trabecular meshwork with very short, low-energy pulses that are absorbed selectively by those cells and do not heat or scar the surrounding tissue. The treated cells trigger a biological response (a mild remodeling and clearing of the meshwork) that improves outflow over the following weeks. Because no tissue is destroyed, the treatment can be repeated.

The procedure

A numbing drop is placed and a contact lens held on the eye to view the angle. The laser delivers about a hundred pulses around the meshwork in a few minutes; most patients see flashes and feel nothing, or at most a light tapping. Pressure is checked afterward, and anti-inflammatory drops may be used for a few days. There is no restriction on activity.

Results

Pressure falls over one to three months. In large studies, around three quarters of patients respond, with an average reduction of a fifth to a third, often lasting several years. A large randomized trial in newly diagnosed patients found SLT as a first treatment kept three quarters of them drop-free at three years, with better pressure control and fewer surgeries than the drop-first group. When the effect wears off, SLT can be repeated with similar success.

Who it suits

• Newly diagnosed open-angle glaucoma or ocular hypertension, as an alternative to starting drops
• Patients on drops who struggle with side effects, cost or remembering doses
• Patients whose pressure is not quite at target on drops, as an addition
• Patients with pseudoexfoliation glaucoma, who often respond well, and pigmentary glaucoma, which can respond but needs lower laser energy and closer pressure checks afterward

SLT does not treat angle-closure glaucoma, for which iridotomy or lens extraction is used, and it is less effective in advanced disease needing very low pressures.