What to expect from laser iridotomy

Written by: Professor Kin Sheng Lim
Published: | Updated: 27/07/2021
Edited by: Emma McLeod

If you are scheduled to undergo laser iridotomy for glaucoma or considering the procedure, you may be wondering how it works, what happens before, during and after the procedure as well as if there are risks. Learn from Mr Kin Sheng Lim, a leading consultant ophthalmologist, about what to expect from your laser iridotomy.

A close of up a greenish blue eye

What is laser iridotomy?

A laser peripheral iridotomy is a procedure used to treat angle-closure glaucoma. If you have healthy eyes, the fluid in your eye (aqueous humour) flows through your pupil into the front of your eye and drains away through drainage channels called the trabecular meshwork.  However, if you have angle-closure, these drainage channels are obstructed by the iris (the coloured part of your eye) which has moved forward. Because of this, the aqueous humour cannot leave your eye, so your eye pressure increases (also known as intraocular pressure). The build-up of pressure injures your optic nerve - the nerve that carries information from your eye to your brain - and damages your vision.


A laser iridotomy uses a laser beam to create a small hole in your iris. This forms a permanent passage, of which aqueous humour can flow through, and pushes the iris tissue backwards, thus unblocking the drainage channels. Aqueous humour is a completely different fluid to your tears and they will not be affected by the operation.


It is important to remember that this procedure is performed to save the sight you still have. It will not restore any sight you may have already lost, neither will it improve your sight. The laser treatment is to prevent a sudden (acute) rise in pressure within your eye. Without having this treatment, you are at risk of developing sudden glaucoma and irreversible blindness.


Is laser iridotomy the same as YAG iridotomy and peripheral iridotomy?

Yes. They are all the same treatment.


What can patients expect on the day of the procedure?

On the day, please take your eye medication as normal on the morning of the laser treatment. You will need to visit the outpatient clinic for about 1-2 hours. We will carry out the treatment in one of our laser treatment rooms. You don’t need to do any special preparations such as fasting or changing into operating theatre clothes.


You will then have some more drops put into your eye. These are usually a miotic (drops to make your pupil smaller), a drop to lower the intraocular pressure (the pressure inside your eye due to aqueous) as well as an anaesthetic eye drop to numb your eye.


You will then sit at a machine similar to the machine used to examine your eyes at the eye clinic. However, there is a special laser attached to this machine. The doctor will put a special contact lens on your eye before applying the laser beam. This lens allows the doctor to view your iris clearly so he or she can apply the laser and make the hole in your iris.


The treatment usually takes less than 10 minutes. It’s usually painless thanks at large to the anaesthetic drop used to numb your eye before the laser, but you might experience slight discomfort when the laser is being applied.


After the procedure, you will return to the waiting area. Your doctor or nurse will check the eye pressure about one hour later before you are discharged.

Are there any risks associated with a laser iridotomy?

Complications after this treatment are uncommon. Occasionally, your eye pressure will rise immediately after laser treatment. If this happens, you may need extra treatment before you can go home. This treatment usually comes in the form of eye drops, but it comes in the form of tablets too.


Your doctor will let you know which treatment you need and advise you of how long you need to take the treatment for. If we do treat you with eye drops, a doctor or nurse will put them in your eye before you leave the hospital. You will be asked to remain in the clinic until your eye pressure has reduced to a satisfactory level. This should take a few hours at most.


A small number of patients find that extra light enters through the new opening, which can be a little distracting at first. However, most patients find they are soon able to ignore this. Other complications are bleeding in the eye from the laser and inflammation, usually small and can be treated with more frequent steroid drops. In some patients, laser iridotomy alone may not be enough to open the drainage channels and you may require another type of laser or even surgery.


Certain symptoms after surgery could mean that you need to be treated quickly, including:

  • excessive pain
  • loss of vision
  • halos around light
  • the eye becoming increasingly red


Are there any alternatives to laser iridotomy?

An alternative to laser iridotomy is a cataract operation, which is not suitable for everyone. It also carries a greater risk of complications. There are no other alternatives to open up the drainage channels in your eye.


Some patients with this condition also develop a long-term (chronic) rise in their eye pressure. In this case, you may need drops or other treatments in the long-term to keep your eye pressure within safe limits.


Is much aftercare needed?

You will be given steroids drops to be used for one to two weeks and you will be reviewed in the clinic a few weeks later to make sure your eye has responded well to treatment and to see if the treatment was successful. If you have discomfort once you get home, we suggest that you take your usual pain reliever following the instructions on the packet.


It is normal to have gritty, sticky eyelids and mild discomfort for a couple of hours after laser treatment. The eye drops can also take some time to wear off, and you should not be alarmed if your pupils are still small for several hours after treatment.


The drops can also cause a mild to moderate headache across your brow. As they make your pupil small, you might find that a dim or dark room is quite dark. Do not panic. The drug will have worn off by the morning, and your pupils should be back to their normal size again.


You may also find that your vision is a little blurred. This is normal and your vision should return to how it was before the laser within two hours.

What do I need to do after I go home?

We may prescribe anti-inflammatory drops after your laser treatment. These help to minimise inflammation (not infection) within the eye. People normally only have to take these for a week at most - the doctor will tell you how long you need to take them for. You don’t need antibiotics because your eye doesn’t have an open wound.


I was using glaucoma drops before the iridotomy. Should I continue?

If you are using glaucoma drops, please check with the nurse or the doctor whether or not you need to continue using them on your treated eye. It is usual to continue using them unless your doctor has said otherwise.


If you are using glaucoma drops to the untreated eye, please continue to use them unless clearly instructed otherwise. Otherwise, you can do all of your daily activities as you would normally without any problems.


Mr Kin Sheng Lim is highly practised and skilled in performing laser iridotomy among many other treatments – see Mr Sheng Lim’s Top Doctors profile to learn more and to get in touch.

By Professor Kin Sheng Lim

Professor K. Sheng Lim is an internationally renowned consultant ophthalmologist based in London specialising in glaucoma and cataract surgeries.

After qualifying from University of Leicester, he obtained his doctorate in medicine from University College London, receiving most of his general ophthalmology training at Moorfields Eye Hospital, the Western Eye Hospital, and the Royal Free Hospital. He underwent further glaucoma training at Moorfields Eye Hospital and The Mayo Clinic in Minnesota, USA. Professor Lim is a consultant, the head of ophthalmology research and the director of the KCL Frost Eye Research Department at St Thomas' Hospital.

He is also the professor of glaucoma studies (Ophthalmology) in the Faculty of Life Sciences and Medicine at King's College London, and has been involved in many landmarked studies in the treatment of glaucoma and is currently the principal and chief investigators of many on-going studies. He is at the forefront of his field, with clinical expertise in cutting-edge glaucoma surgeries such as iStent, Hydrus, PreserFlo (MicroSHunt), ECP laser, laser iridotomy, SLT laser, trabeculectomy, Baerveldt tube and more. He also specialises in cataract surgery, and carries out high volumes of cataract surgery each year.

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