SLT – laser for glaucoma and ocular hypertension

Selective laser trabeculoplasty for open-angle glaucoma)

SLT is a laser procedure designed to lower the pressure in the eye in patients with glaucoma or ocular hypertension.

Who is suitable for SLT?

Patients who have ocular hypertension, primary or secondary open angle glaucoma and need to lower their intraocular pressure (IOP) may be suitable for the procedure.

How does the SLT technique work?

SLT works by using pulses of laser applied to particular cells in the eye.  This triggers a process in the eye which will improve drainage and therefore lower the IOP.

How is SLT performed and will it hurt?

SLT is an outpatient procedure and only takes about 15 minutes.  Your eye will be numbed using anaesthetic drops so the procedure will be painless.

How long does it take for the treatment to take effect and how long will it last?

This may be as quickly as a couple of hours after the procedure up to a couple of months.  You will be monitored to check how you have responded.

Will I still need eye drops for glaucoma following SLT?

Everyone is different, so this will be dependent on the individual.  A recent study has shown that 75% of new patients can be free from drops over a 36 month period following treatment with SLT.

What are the risks and side effects of SLT?

There are very few side effects of SLT.  There may be some inflammation of the eye following the procedure, this can be treated with eye drops and usually resolves within a couple of days. Typically the effects of SLT will last several years, however sometimes it may be necessary to have this repeated.

What is the recovery time following selective laser trabeculoplasty?

Little recovery time is needed and you should be able to resume normal daily activities immediately following treatment.

What is the evidence for the effectiveness of SLT?

The results of a pioneering clinical study conducted by Moorfields Hospital called LIGHT (Laser in Glaucoma and Ocular Hypertension Trial) and published in March 2019 indicated that laser-based treatment in newly diagnosed cases is more successful than the traditional intraocular pressure lowering eye drops.


This landmark study showed that for 80 per cent of new patients the laser can deliver ‘drop-free’ intraocular pressure control over 36 months with very few if any side-effects. This is achieved by the laser stimulating the body’s own healing response. In effect, the laser is absorbed by pigmented cells in the eye which improves the flow of fluid leading to a reduction in the pressure on the eye.

Laser iridotomy for narrow angle glaucoma

Patients who are found to have narrow angles and are at risk of developing angle closure glaucoma can be treated with a procedure called YAG laser iridotomy. In this procedure laser is used to make a small hole in the edge of iris near the trabecular meshwork so that aqueous can flow directly into the anterior chamber angle without needing to flow around the iris through the pupil. Acute angle closure is usually treated in hospital with a combination of medicines and eye drops to bring down the pressure, followed by a laser iridotomy.

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