Selective Laser Trabeculoplasty (SLT) is an alternative to medication to lower pressure in the eye.

SLT has largely replaced the old ALT (Argon Laser Trabeculoplasty)

ALT induced thermal damage to the trabecular meshwork and so was not able to be performed more than several times. The newer SLT does not induce any thermal damage to the trabecular meshwork and so can be repeated many times.

Traditionally, the treatment of glaucoma has been medication and if this failed to control the pressure then laser treatment and if that too failed then surgery.

Today, it is not uncommon to commence treatment with laser and then introduce medication if laser fails or doesn’t lower pressure sufficiently.


As SLT does not require the patient to do anything, it gets around the most common problems of medication which are side effects and failure to use them properly or forgetting to use them.


The effect of SLT is not immediate but can take a month or more to lower pressure. Further, its peak pressure lowering can take up to six months.

The pressure lowering duration is variable, ranging from six months to more than four years. Once its effect wears of, it can be repeated. It is unclear how many times it can be repeated but evidence is emerging that if may cease to be effective after three or more applications.


SLT does not work in everyone with an approximate 20% failure rate. Further more, its effect is not permanent, wearing of after 6 months to 5 years. It can however be repeated. Rarely, a paradoxical pressure rise can occur immediately after its done. This is usually very short term but can result in high pressures.

Some patients experience light sensitivity and a slight ache in the eye for a day or so after having SLT


SLT is for anyone who does not wish to use medication or who react to medication. It is also good for those who have trouble instilling eye drops or who are forgetful.

There is some evidence that patients who have SLT first and then go on to medication later, may have a better long term outcome than if medication is used first. This however is still under investigation.

It is safe to say however that there is no real downside to using as first line and so probably everyone should trial it before staring medication.

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