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Selective laser trabeculoplasty is performed for patients with glaucoma or high eye pressure.

Fluid in the eye (aqueous) is produced by the ciliary body, and drains out through the trabecular meshwork (drainage pathway) in the drainage angle. Sometimes the trabecular meshwork becomes unable to cope, thus preventing the aqueous from draining out easily. This causes pressure to build up in the eyeball. When the pressure in the eye is too high, it can cause damage to the optic nerve and permanent vision loss – this is called glaucoma.

Doing the laser reduces the eye pressure, which in turn reduces the risk of further optic nerve damage from glaucoma.

What does the laser do?

How the laser works precisely is unclear. What is known is that the laser stimulates the cells and tissues in the trabecular meshwork to work harder to drain aqueous out from the eye. This “unclogs the guttering” and helps to reduce the eye pressure. The pressure-lowering effect of the laser is not immediate, and can take up to 4 to 8 weeks to become apparent.

If selective laser trabeculoplasty does not work initially (approximately 20% do not succeed the first time), a second treatment often does.

What does the laser treatment involve?

The laser is performed with the patient seated at the laser machine. The laser is delivered through a special contact lens that is placed on the eye after it has been numbed with local anaesthetic eye drops. You may feel some mild discomfort with each laser shot. The laser itself takes only a few minutes to perform and is completed once the entire trabecular meshwork has received laser treatment.

Diagram of an eye where the laser beam transfers through the contact lens towards the drainage pathway to reduce pressure in the eye.


The pressure-lowering effect of the laser is not permanent, and can last from 6 months to 2 years plus. Generally with 2 treatments, the effect should be maintained for about a year. As selective laser trabeculoplasty is very safe, it can be repeated multiple times as necessary.

What to expect

  • You will be in the hospital for at least 2 hours.
  • You will have drops put in your eye to prepare the eye for the treatment, so you will be unable to drive home.
  • Local anaesthetic drops will also be put in your eye before the procedure.
  • Treatment is delivered through a lens which rests against the eye.
  • Please take all of your usual medications prior to your appointment, unless otherwise advised by your doctor.
  • Usually no additional eye drops are required after laser treatment. However, continue all other regular drops (ie glaucoma drops).
  • Side effects may include discomfort, sensitivity to light (photophobia), headache, or blurry vision for several hours afterwards. Wearing sunglasses (with your prescription, if required) can make the trip home more comfortable.
  • Please arrange for someone to come and pick you up and drive/take you home after the procedure.

More information

The Royal Victorian Eye and Ear Hospital
Phone: (03) 9929 8666

Glaucoma Australia (Victoria)
Phone:  1800 500 880

Disclaimer This document describes the generally accepted practice at the time of publication only. It is only a summary of clinical knowledge regarding this area. The Royal Victorian Eye and Ear Hospital makes no warranty, express or implied, that the information contained in this document is comprehensive. They accept no responsibility for any consequence arising from inappropriate application of this information.

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  • Selective Laser Trabeculoplasty (SLT) #162
  • Owner: Laser
  • Last Reviewed: June 28, 2023
  • Next Review: June 28, 2028