Laser Iridotomy
Chat Highlights
February 4, 2009

On Wednesday, February 4, 2009, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Laser Iridotomy".

Moderator: Welcome Dr Pro. Our topic is Laser Iridotomies. What is an iridotomy and when would a patient require one?

Dr. Pro: An iridotomy is a hole made in the iris with a laser, usually in cases of a narrow angle.

P: What is the difference between an iridotomy and an iridectomy?

Dr. Pro: Great question! They are essentially the same, but an iridectomy refers more to a surgically made hole in the iris, while an iridotomy is made with a laser in an office setting. Iridectomies usually create a larger hole.

P: Is an iridotomy successful with all types of angle closure glaucoma?

Dr. Pro: No, not in all cases. It will be helpful to review the causes of angle closure. One category of angle closure includes persons with phyiologic narrow angles (they are born with a particular eye shape with which the narrowness of the angles progresses with age); next are persons who have narrow angles secondary to a tumor behind the iris; and then there are persons who have narrow angles due to chronic inflammation, which can cause a progressive scarring of the angle.

Persons from the first group respond well to a laser iridotomy; persons from the next two groups respond poorly, if at all.

P: Could you please tell us what it means to respond well or respond poorly to an iridotomy?

Dr. Pro: I mean whether the angle appears more open and if the view of the trabecular meshwork (the drain) is better. This means that the chance of having an angle closure attack is lessened.

P: I had iridotomies two years ago. I see streaks of light, moving with my eyes, and there is a line of bright light right in the middle and my eyes are sore. My vision has decreased from 20/20 to 20/100. What can be done to fix my problems?

Dr. Pro: Well, that question brings up adverse effects from a laser iridotomy. More common side effects are temporary blurry vision, soreness, IOP spike, and closure of the iridotomy; much more uncommon are long-term problems such as chronic inflammation, chronic ocular pain, or visual disturbances such as you describe.

Loss of vision is very unusual, but it is concerning and needs to be evaluated to see if the ocular surface is irritated, or if a cataract has developed, or there a retinal problem, for example.

P: For eyes with narrow angles, that are otherwise healthy and with normal IOP, why not wait to perform laser iridotomy, especially in developed countries?

Dr. Pro: It is certainly an option, especially if the angle is not overly narrow. I would add that determination of the angle configuration is somewhat subjective from the examiner. There are more objective measures such as the use of imaging devices, but they are rarely used in routine cases.

P: What complications of iridotomy do you warn patients of? Do you inform patients that their iridotomy is prophylactic?

P: When I had mine done, my doctor told me it was a preventive measure and had side effects.

Dr. Pro: I tell them that the laser can help to prevent an angle closure attack. They are told that the laser is not used to improve vision (a common question!). I warn them of common complications such as I mention above. I always discuss the rare complication of visual disturbance mentioned above, which is usually transient, but sometimes chronic.

P: My first iridotomy was so painful I vomited and the pain lasted a week. Now the second eye. What can be done to alleviate pain during and after the procedure?

Dr. Pro: That is very unusual. I have never had a patient experience that kind of pain. In that case I would make sure to check that the IOP was not elevated. It is more common for a patient to require a medication for anxiety prior to the Peripheral Iridotomy (PI). Only topical anesthesia is required to perform the PI (so the lens can be placed on the eye).

P: Dr. Pro, you say "So the lens can be placed on the eye." Isn't a lens put on before a Yag Laser? Is it the same type of lens?

Dr. Pro: A lens is used to perform a PI. It helps to focus the laser energy and holds the lids open. The one I use is called an Abraham lens.

P: Why are laser iridotomies done preventatively? Why not wait for an angle closure attack?

Dr. Pro: An angle closure attack is dangerous; it is a painful, vision threatening episode which can occur at inopportune times and lead to permanent vision loss, and cataract, corneal and/or pupillary abnormality.

P: Dr Pro, is an iridotomy necessary if the patient does not have an elevated pressure and a grade two angle?

Dr. Pro: In these cases I will often recommend observation. I warn about angle closure risk factors such as pain and halos around lights; I warn about using anti-histamines such as Benadryl, which can precipitate an attack.

P: Why not stop preventative iridotomies until a reliable diagnosis can be made as to what angles present a true closure risk?

P: I have had a malignant attack of angle closure, in the Emergency Room with intravenous running to get my high pressure down. It is nothing you want to mess with in my opinion, so I have no regrets agreeing to my first iridotomy that lasted years.

Dr. Pro: Good point!

P: Can a laser iridotomy increase the chance of cataracts?

Dr. Pro: Possibly, the jury is still out. Clinically I can't say that I really see any increased incidence.

P: How accurately can you estimate the probability and severity of eye damage from acute attack, or from chronic angle closure (which I understand is more common, at least outside the US)? How does this compare with the frequency and severity of having trouble from a preventive iridotomy? Assuming that it is not easy to estimate either, how do you decide what to recommend to a patient? If the patient understands there are risks in a narrow angle, but also risks with iridotomy, and the doctor has explained it all, how is he to decide what to do?

Dr. Pro: Well, let's begin by stating that the risks of a laser iridotomy are fairly low and that the benefits (preventing an angle closure attack) would outweigh the risks in a person with a critically narrow angle.

But I should mention that the prevention of chronic angle closure glaucoma has not been definitively proven, thus I always tell the patient that the primary reason to perform the laser is to prevent an angle closure attack. I should also add that the PI does not usually bring down the IOP, except when done in the setting of an acute angle closure.

P: That answers the first introductory questions, but not the real question of how the doctor decides what to recommend, and how the patient is to decide among risks and benefits he can't fully grasp, and two doctors give differing advice.

Dr. Pro: I'm sorry that I can't answer that question to your satisfaction. It really boils down to a discussion between you and your doctor.

P: Should a patient sign a consent form prior to undergoing a laser iridotomy? A consent form with list of complications?

Dr. Pro: Yes and I also review what a patient can expect to experience during and after the procedure.

P: In our support forum on iridotomies on Prevent Blindness America, patients complain about double vision, glare, decrease of vision, development of cataracts, retinal detachment, corneal problems, visual aberrations, permanently high IOP and so on. I had normal eyes and needed glasses, but now my eyes are ruined; I know many with worse problems than I have. I believe severe problems are much more common than doctors are letting on.

Moderator: How common are severe complications after laser iridotomies?

Dr. Pro: These are all possible and very unfortunate complications, but they are very rare and difficult to put an exact number on. A forum such as this is very useful and I am glad that patients can get together to support one another, but the vast majority of patients who have these procedures do not experience permanent complications and do not join a support forum.

P: People with open angle glaucoma are not in danger of angle closure are they?

Dr. Pro: Not in most cases. There are rare causes of angle closure due to other things like a specific medication, tumors, or displaced lenses, etc.

P: I have severe monocular double vision in the eye that had the iridotomy. My eye still has inflammation. What can I do? I normally patch my eye and only see with the eye that didn't have an iridotomy.

Dr. Pro: Monocular double vision is usually from the corneal surface, or from a cataract, but in your case is probably from light reaching the retina from the PI. That may improve with time. The inflammation should be addressed. Chronic inflammation can lead to cataracts, glaucoma, or retinal swelling. Some patients with chronic inflammation need a Uveitis specialist to help monitor an anti-inflammatory regimen.

Moderator: Thank you Dr. Pro. Do you have any closing thoughts for our participants this evening?

Dr. Pro: You are all welcome. I hope all the individuals who have experienced problems after the Peripheral Iridotomy have a speedy recovery. Thanks for your questions. Good night everyone.

On March 4, Dr. Werner discussed "Bleb Leaks and Other Complications" in the Chat room. Click here for highlights of that meeting.

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