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Laser peripheral iridotomy treatment

Patient information A-Z

What is laser peripheral iridotomy?

An iridotomy is when a small hole is created with the laser beam in the outer part of the iris (coloured part of the eye).

Why is laser peripheral iridotomy performed?

It is performed to treat or prevent a sudden rise in pressure inside the eye (acute glaucoma). A sustained rise in pressure can cause permanent loss of side and central vision. The iridotomy allows fluid to circulate freely within the eye, minimising the risk of a sight-threatening pressure rise.

There are three reasons for this procedure:

  • to prevent a sudden attack of acute glaucoma
  • to treat an attack of acute glaucoma
  • to treat slow onset of glaucoma when the drainage channel is very narrow

This laser procedure is performed to preserve sight. It will not restore or improve the sight.


Complications are uncommon.

However, occasionally after the treatment there may be a rise in pressure and some inflammation shortly after the treatment. The pressure will be checked before you go home and if very high, you will need to have extra treatment (drops, tablets or sometimes an injection). You will also need to remain in the Eye Clinic until the pressure has dropped to a safe level.

Other risks include:

  • bleeding in front of the iris causing some hazy vision that usually clears within an hour
  • clouding of the cornea (window) of the eye
  • cataract

The day of your treatment

The treatment takes approximately 15 minutes, but please allow between one to two hours at the hospital. Your treatment will be carried out in the Eye Clinic. On arrival the doctor will explain the procedure, ask you to sign the consent form and numb your eye with drops. We will undertake the procedure with you sitting and resting your chin on an instrument similar to that used to examine your eye. We will place a contact lens on the eye to steady it and focus the laser beam. You will see some bright flashes of light, hear a clicking noise and may feel slight discomfort.

After your treatment

The doctor will apply some more eye drops and we will check the pressure one hour after the treatment. If the pressure is at a safe level you may return home. Your eye may become pink, sore and the vision can be blurred for several hours afterwards. For this reason you will need someone to take you home.

We will prescribe additional medication for a few days to prevent inflammation and a rise in pressure. . If you experience any discomfort please take your usual pain relief treatment.

You should continue to use all your anti-glaucoma medication unless specifically instructed otherwise.

We will arrange an appointment to be made for a check-up in the Eye Clinic shortly afterwards. A number of patients will require more than one laser procedure. This is not unusual.

If you are worried after the laser treatment

In the unlikely event of pain not relieved by simple painkillers, a drop in vision or a very red eye, please contact glaucoma nurses Mon to Friday 08:30 to 17:00 on 01223 274889. If it’s an emergency or outside of these times, please call the Eye Emergency Clinic 01223 217770.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151