Glaucoma is a potentially blinding condition which requires life-long eye pressure lowering. There are three main ways in which glaucoma is managed. These include pressure lowering with medication which is usually administered in drop form to the eye, Glaucoma lasers and surgery (Stents or open surgery).


This document will focus on Selective Laser Trabeculoplasty (SLT) treatment for glaucoma.


  • To reduce the eye pressure one needs to either reduce the amount of fluid produced by the eye internally or increase the amount of fluid leaving the eye.
  • Some glaucoma drops reduce the amount of fluid produced and others increases the amount of fluid leaving the eye.
  • Surgery increases the amount of fluid leaving the eye.
  • SLT laser also increases the amount of fluid leaving the eye thus causing decreased eye pressures and safety against glaucoma damage.
  • The laser is NOTa cutting procedure and no wounds are created.
  • The SLT laser applies heat or energy burns to the outflow portion of the eye called the trabecular meshwork.
  • On microscopic examination of this portion of the eye, the trabecular meshwork has the histological appearance of a sponge.
  • Over time in a glaucoma patient’s eye, this “sponge” gets blocked by microscopic cells and debris which leads to reduced fluid outflow from the eye and subsequent increased eye pressures.
  • By doing SLT laser the energy applied to this “sponge” tissue causes the body to clean the “sponge” outflow tracts allowing the fluid to escape more rapidly from the eye via the normal outflow mechanism.
  • SLT laser does NOT make “holes” in the eye to allow fluid to escape.
  • In glaucoma our aim is usually to achieve eye pressure below 16mmHg which is seen as safe – in some cases we want the pressure even lower and closer to 10mmHg.
  • SLT laser can reduce eye pressures by between 20 and 30% in most cases.
  • Studies have shown the effect of SLT laser to be equally as good as a strong glaucoma drop.
  • The general effectiveness or success rate of SLT laser is estimated to be around 75%.
  • This implies that one out of 4 patients who has SLT laser will not have adequate pressure lowering and will require additional management like drops or surgery.
  • The effect last on average between 2 and 5 years – long term studies have shown that at 10 years 60% of patients will still have good pressure lowering effect from a SLT laser.
  • If the effect wanes over time it is still possible to repeat the laser treatment.

Basic procedure:

  • The procedure is quick and done in the rooms (NOT in theatre).
  • The patient is prepared for the procedure by placing a few anesthetic eye drops.
  • The procedure is performed on a slit lamp microscope exactly like the one used to examine eyes with.
  • A contact lens device is placed on the eye to perform the procedure
    • This is not painful but gives a strange feeling
  • The procedure takes about 5-10 minutes to complete.
  • After the procedure, the patient can go home and is usually prescribed an anti-inflammatory drop for a week to place in his eyes.

What to expect:

  • The procedure is not painful though some patients call it uncomfortable.
  • The procedure leads to blurring of vision for a few hours
    • It is advisable to have someone drive you on the day of the procedure.
  • Post-operative pain is extremely uncommon and typically the patient is back to normal within a few hours.
  • The patient is typically seen back at the rooms for a pressure check 1 month after the procedure to check the response to treatment.

The potential complications:

  • This procedure has a highly favorable side-effect profile and complications or problems are exceedingly rare and mostly temporary
  • Inflammation
    • The effect of the laser creates inflammation in the eye – this is part of the purpose of the laser.
    • Inflammation can cause some light sensitivity and blurring of vision.
    • This on average lasts about 6 hours or less.
  • Eye Pressure Spike
    • A temporary pressure increase can occur which also typically lasts less than 12h.
    • It is very uncommon to have a persistent pressure spike after the procedure and typically occurs in some subtypes of pigmentary glaucoma.
  • Failure of effect
    • This can occur in 1 out of 4 patients where the effect of the laser is not good enough to allow eye pressures to lower to adequate levels.
    • In these cases the patient will either need a repeat laser, eye drops or surgery.