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Glaucoma is often caused by the build-up of fluid in the eye (called aqueous humour, or just aqueous). This causes pressure in the eye (called intraocular pressure or IOP) to increase, which damages the optic nerve and leads to vision loss. Laser treatment is used in glaucoma to decrease the amount of fluid in the eye, either by increasing the drainage of fluid out of the eye, or by reducing the amount of fluid that is made. This page describes the most common laser treatments, how they work to treat glaucoma and what to expect from if it’s recommended for you.

Selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT)

SLT and ALT are used to treat open angle glaucoma or ocular hypertension. The laser is targeted at the drainage channel in the eye, opening it up so that fluid can drain out of the eye more easily. This lowers IOP, which reduces the risk of damage to the optic nerve.

The treatment is done in a normal eye clinic not an operating theatre, and usually lasts around 20 minutes. You will be given a local anaesthetic to numb the eye and you’ll probably be given eye drops to use afterwards to reduce swelling.

SLT and ALT are very similar. SLT is a newer form of the treatment, which uses a slightly gentler laser.

Laser iridotomy and iridoplasty

Laser iridotomy and laser iridoplasty are used to treat angle closure glaucoma or narrow angles. This is where the iris (the coloured bit of the eye) is pushed forward, blocking off the natural drainage pathway for the fluid in the eye. This causes the fluid in the eye to build up, increasing IOP and damaging the optic nerve.

In iridotomy, a small hole is made in the iris with a laser. This allows the iris to return to its original position, opening up the natural drainage channel.

In iridoplasty, the laser is targeted at the iris where it blocks the drainage channel, to shrink the iris away and open up the channel again.

In both treatments, opening up the channel means the fluid can drain out of the eye, reducing the IOP.

The treatment is done under local anaesthetic, meaning you’ll be awake but the eye will be numb. You will probably be able to go home the same day. You may be given eye drops to reduce swelling.

Cyclodiode laser (including MicroPulse)

This laser is used to treat glaucoma when other types of treatment have failed. The cyclodiode laser targets the ciliary body, the part of the eye where aqueous humour is made. The laser reduces the amount of aqueous being made.

The treatment usually lasts around 20 minutes. You’ll be given a local anaesthetic to numb the eye and you will probably be given eye drops to use afterwards to reduce swelling.

MicroPulse cyclodiode works in the same way, but uses short bursts of energy that allow the ciliary body to cool between pulses and reduce the damage to the surrounding tissue.

After care

After laser treatment it’s likely that you’ll be given eye drops to help with swelling or to reduce the chance of infection. It is likely your eyesight will be blurry for a short time after the treatment. You’ll be asked to attend follow-up appointments to check your eye is healing and the laser treatment is working. It is very important to attend these appointments and to keep putting in any eye drops you have been prescribed.

What are the alternatives?

There are other treatments available for glaucoma which may be recommended to you, for example eye drops, trabeculectomy or MIGS.


Our glaucoma helpline advisors are also on hand to answer any questions you may have and to provide support whenever you need it.

Call 01233 64 81 70 or email
(Monday – Friday, 9.30am – 5.00pm)