Laser Iridotomy
Why might I need Laser lridotomy?
Laser iridotomy is a treatment used for patients who have, or who are at risk of developing, a particular type of glaucoma called angleclosure glaucoma.
There are three reasons for this procedure:
1. To prevent an attack of acute glaucoma
2. To treat an attack ofacute glaucoma
3. To treat a narrow or closed drainage channel
This laser procedure is performed to preserve sight. It will not restore or improve the sight.
How does Laser lridotomy work?
Normally, the production of fluid within the eye is balanced by the fluid draining out of the eye. Figure 1 shows the normal flow offluid in the eye (curved arrow). If enough fluid cannot escape through the drainage canal due to “crowding” of the angle by the coloured part of the eye (the “iris”), then the eye pressure will rise. High pressure in the eye can cause damage to the optic nerve and can lead to permanent loss of vision. Figure 2 shows the drainage canal being blocked by the iris resulting in the fluid within the eye (aqueous humour) unable to get access to the canals.
The laser delivers a highly concentrated beam of energy, which is used to make a small hole in the iris. This small hole allows the aqueous humour to flow freely again into the front chamber of the eye and into the drainage canal by bypassing the crowding. It also helps prevent the iris from being pushed forward on to the delicate drainage system and restricting the flow of fluid.
If the iris is darkly pigmented it may be necessary to pre-treat the iris with another type of laser to make it easier and safer for the laser to make the small hole in the iris. If this is the case it will be discussed with you.
The day of your treatment
- The laser treatment is performed in the outpatients clinic.
- When you arrive at the clinic your vision will be assessed and drops will be put into your eye(s). These are to help with the treatment.
- Please note one of the drops often causes “brow or headache’’. This will wear off after a few hours.
- The doctor will explain why you are having laser treatment, if you have not been told at an earlier appointment. They will also ask you to sign a consent form.
- You will be taken into the laser room where you will be sat at a machine with a chin and headrest.
- The doctor will put more drops in to numb the front of the eye before a special magnifying contact lens with cold gel is placed on the eye to allow the doctor the perform the treatment and to help keepyoureye open. With the lens on the eye you may feel a “cold” and sometimes”pressure” sensation but the lens will not hurt.
- The laser treatment will then be given and takes about 1 0 minutes to perform. When the laser is being applied you may experience a”sharp discomfort” in the eye initially.
- 1-2 hours after the laser, your eye pressure will be checked.
- You will then be given a prescription for anti-inflammatory (steroid) eye drops. If your eye pressure is raised after the laser you may be prescribed some eye drops or tablets for a short while to protect your eye.
Risks or side effects of this Treatment
Complications after this treatment are uncommon. The main risks are:
1. A rise in the eye pressure (intraocular pressure) – this may occur immediately after laser or be detected at your follow up appointment. If this happens, you may need extra treatment in the form of eye drops and sometimes a tablet. If the eye pressure remains persistently elevated despite extra treatment then surgery may be required to lower the eye pressure.
2. Bleeding/Inflammation – Bleeding occurs when a small vessel bursts during the laser and is stopped by applying pressure with the lens used during the laser. Following the laser, you will be prescribed steroid drops to reduce inflammation in the eye, however, if there is still inflammation in the eye at your follow-up appointment then the steroid drops maybe continued for 1-2 weeks longer.
3. Visual disturbance – Visual disturbance can occur following the laser. If it occurs you may notice any of the following:
• A line in the vision (horizontal or curved in upto 11% of patients)
• Ghosting • Glare • Shadow • Crescents
• Short lived blurred vision (up to 48 hours after laser)
If you experience any visual disturbance, it usually settles down or disappears overtime (up to 12 months). However, 1:1000 people may still have these symptoms at 12 months.
4. Change in glasses prescription
5. Reduced/loss of vision – There is a small risk or reduced vision following the laser. The risk of loss of vision is low.
6. Need for repeat laser (see below)
What is the risk of not having the treatment?
The risks of not having treatment depends on your condition when you are first seen by an eye doctor for this condition.
If your eye pressure is normal, there is a small risk of developing sudden high pressure (“acute glaucoma”) or progressive closure of the drainage angle over time. However, if your eye pressure is elevated (without damage to your nerve or “glaucoma”) there is a significant risk of developing glaucoma within a five year period.
Furthermore, regardless of your eye condition there is also a small risk of a sudden, significant rise in the eye pressure, which can lead to sickness, severe pain, an inflamed eye (“red eye”) and reduced vision (which can be permanent). This condition is called acute primary angle closure or “acute glaucoma” and is considered to be an eye emergency.
What happens after the procedure?
You will be seen in the outpatient department 1-2 weeks later to make sure your eye has responded well to treatment.
If you have discomfort once you get home, we suggest that you take regular paracetamol forl-2 days.
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 instilled before the laser can also cause a mild to moderate headache across your brow, and because they make your pupils small, you might find that a dim or dark room is darker than usual. The drug will have worn off by the following morning and your pupils should be back to their normal size again.
You may also find your vision is a little blurred. This is normal, and your vision should return to how it was before the treatment over the next 1-2 days.
What do I need to do after I go home?
We will prescribe anti-inflammatory (steroid) eye drops after your laser treatment which help to minimise inflammation of the eye. The steroid drops are to be used every hour for the first day (daytime only and not during the night) and then four times a day for one week then STOP.
If you are using glaucoma drops, please check with 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.
You can do all of your daily activities as you would normally without any problems.
How successful is laser lridotomy?
Laser lridotomy is very successful. If in you follow-up clinic visit the iridotomy hole is open and of good size, it can open up the drainage angle in 60-80% of patients. The remaining 20-40% of patients in whom the drainage angle still remains narrow or does not open, may either be observed or require further treatment such as drops or surgery. If further treatment is recommended, this will be discussed with you in detail during your follow-up appointment.
Sometimes, the laser may need to be repeated for the following reasons:
1. Even though the hole appears adequate when created, it may be found to be too small when you are reviewed in clinic a few weeks later.
2. Occasionally a small hole can partly or completely heal up in the first few days after the laser treatment and further treatment to enlarge the hole or create a new hole may be required.
On a few occasions it is hard to penetrate the iris completely on one treatment or a little bleeding occurs so that treatment is suspended and completed on another day.
Laser lridotomy is very effective at protecting against acute primary angle closure.
Author: Rajen Tailor, Consultant Ophthalmologist
