Laser Iridotomy

Laser Iridotomy is a procedure where a laser beam is used to make a small hole in the iris (the coloured part of your eye). The Iridotomy allows fluid produced by the eye (aqueous humor) to circulate freely within the eye, minimising the risk of a sigh-threatening pressure rise (acute primary angle closure or “acute glaucoma”) or reducing the risk of progressive crowding of the drainage angle of the eye.

Laser iridotomy is a treatment used for patients who have, or who are at risk of developing, a particular type of glaucoma called angle-closure glaucoma.

There are two reasons for this procedure:

  1. To treat a closed drainage angle and prevent an attack of acute glaucoma
  2. To treat an attack of acute glaucoma

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

Normally, the production of fluid within the eye (aqueous humor) is balanced by the fluid draining out of the eye. Figure 3 illustrates the drainage angle of the eye showing the normal flow of fluid in the eye (red arrow). If not enough fluid can escape through the drainage angle 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 (glaucoma) and can lead to permanent loss of vision.

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.

Figure 3
Figure 3 - Cross section of the eye showing the region where fluid (aqueous humour) is produced and where it starts to drain out of the eye. The red arrow illustrations the path of aqueous humor flow. Source: National eye institute media library

Laser Iridotomy is very successful. If on your 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.

Although the majority of patient experience no complications following the laser, the procedure has several risks which are as follows:

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 to lower the intraocular 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 may be continued for 1-2 weeks longer.

3. Visual disturbance – Visual disturbance can occur following the laser due to light passing through the opening created by the laser (iridotomy). Visual disturbance can appear in the form of any of the following:

    • A line in the vision (horizontal or curved in up to 11% of patients)
    • Ghosting (a faint double image)
    • Glare
    • Shadow
    • Crescents
    • Short lived blurred vision (up to 48 hours after laser)

If you experience a visual disturbance after the laser, it usually settles down over time (up to 12 months) and becomes either less noticeable or disappears as your brain adapts to it. However, 1:1000 patients may still experience symptoms at 12 months.

4. Change in glasses prescription – this can simply be corrected by a new glasses test at your opticians.

5. Reduced/loss of vision – There is a small risk or reduced vision following the laser. The risk of total loss of vision is low.

6. Need for repeat laser – Sometimes, despite the laser hole (iridotomy) appearing open at the time of laser, when you are examined in clinic 1 to 2 weeks following the laser, the iridotomy may either be closed or too small. If this occurs, further laser treatment will be discussed with you.