LPI - Laser Peripheral Iridotomy
Introduction
A narrow angle is a fairly common condition that in most people will never lead to any major eye problems, but in some people can lead to an attack of acute angle closure glaucoma. With this condition the eye pressure raises very rapidly causing blurred vision, redness, and pain. High pressure can cut off the blood flow to the eye and may cause visual loss or permanent damage to the eye. The treatment for a narrow angle is a Laser Peripheral Iridotomy, or LPI
Anatomy
The eye is filled with fluid, called aqueous, which helps to maintain the round shape of the eyeball. There is a constant supply of the fluid and a place where the fluid drains from the eye, much like your kitchen sink has a faucet and a drain. In the eye the faucet is called the ciliary body. The fluid is made there, travels around the lens, through the pupil, and leaves the eye through the trabecular meshwork (the drain). There is usually plenty of space for the fluid to pass next to the iris and out through the trabecular meshwork. In some people the eye is shaped differently and the drainage area is very narrow. Under certain circumstances, such as dim illumination or stressful situations, the drain can completely close off. When this occurs the fluid continues to be produced and the pressure inside the eye increases over minutes to hours. This is considered an attack of angle closure glaucoma.
If I have a narrow angle what is my risk of angle closure glaucoma?
This is a very difficult question to answer and depends somewhat on how narrow your angles are. The majority of people will not develop angle closure. However, it is impossible to predict who will and who will not get glaucoma. Therefore treatment is recommended for all individuals who are determined to have narrow angles.
What is the treatment for narrow angles?
To lower the risk of acute angle closure glaucoma a small hole is placed in the iris with a laser (laser iridotomy). This laser surgery is done in the office, takes only 15 minutes to complete, and is relatively painless. By placing a hole in the iris an alternate pathway is made for the fluid to reach the drainage area of the eye. This prevents complete closure of the angle and the resulting high eye pressure.
Are there any alternatives to having the laser done?
Laser surgery is the best treatment for narrow angles. If for some reason you did not want the laser there are two options. The first option is no treatment. Without treatment you will still have the small risk of angle closure glaucoma. This risk will slowly increase from year to year as the angle becomes narrower as you age. The second option is to use an eye-drop to lower the risk. The eye drop needs to be used 3-4 times daily, and may make the vision dim or blurry. It will reduce the risk of angle closure, but can’t completely prevent it.
Are there side effects of the laser?
Yes, but generally they are minimal. In most people there is a small elevation in the eye pressure and some inflammation inside the eye. These problems are easily treated with medications. Before the treatment you will usually be given some drops to prevent the pressure increase. You will also usually be given anti-inflammatory eye drops to use for 5-7 after the laser to help with the healing process. Less than 5% of people will have a dramatic increase in eye pressure in the first few hours after the laser. Usually this is treated with additional medications, but in extremely rare instances emergency surgery may be needed.
Will the laser affect my vision?
In most cases you will not be aware of any differences in your vision. Approximately 1-in-100 people will report a faint line or crescent of light in their vision. This is caused by stray light coming in through the new opening in the iris. Most people report that the symptoms get less noticeable over time, but if they persist there are several techniques that may improve the visual changes. If your eye has had other problems in the past such as chronic inflammation, cataracts, or corneal swelling, the laser may cause short-term increases in inflammation or corneal swelling. This may make the vision worse for days-to-weeks after the laser. In most cases the vision improves with the use of medications. It is extremely rare for a laser iridotomy to cause visual loss.
What am I to expect on the day of surgery?
After arrival your vision and eye pressure will be checked. Your doctor will review the procedure with you and answer any question that you may have. You will need to sign a consent form before the procedure. You will be given several drops to prepare the eye for the laser. The laser surgery takes 10-15 minutes depending on which lasers need to be used. You may feel a slight burning and/or snapping sensation. Most people describe this as uncomfortable rather than painful. When the laser is complete you will be given additional drops to prevent the pressure from increasing. You will then need to wait in the office for 30-60 minutes for a pressure check. If the pressure is fine you will be able to leave. The vision will be dark and blurry for 2-3 hours after the surgery because of the bright lights and lenses used. Because of this we recommend that you have someone with you to drive you home. This is especially true if you have poor vision in your eye that did not have the laser. A follow-up appointment will usually be arranged for 2-4 weeks after the laser.
Are there symptoms to watch out for after the laser?
After any eye surgery there are certain signs and symptoms to look for. If you experience significant redness, light sensitivity, blurred vision, headache, halos around lights, or nausea you should contact your doctor immediately. This could be from increased inflammation or high pressure in the eye.
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