Monday, November 20, 2006

Section 8-A-2: Laser Peripheral Iridotomy (LPI)

Patients with narrow, occludable angles or who have an attack of acute angle closure glaucoma are treated with laser peripheral iridotomy (LPI). LPI is done to create a bypass channel for aqueous to flow from behind the iris to the front of the iris, and subsequently, into the drainage angle (see Chapter 4, Section 4-D). Prior to the advent of laser, a surgery was necessary to create this bypass (surgical iridectomy). Nowadays using laser energy, a hole is made in the peripheral part of the iris, typically under the upper eyelid. The procedure is well-tolerated by patients under topical anesthesia. Several different lasers are utilized for this procedure including the Argon and YAG laser. Sometimes a combination of the two lasers is used to create the LPI. The Argon laser typically requires pigment for the uptake of the laser energy and therefore, is better for darker colored (i.e., brown) eyes. The YAG laser disrupts the tissue and is better suited for lighter colored (i.e., blue) eyes.

The procedure typically lasts 10-15 minutes. Prior to the procedure a glaucoma medication is given to prevent any post-laser IOP elevation. In addition, pilocarpine (cholinergic agent – see Chapter 7) is given to make the pupil smaller so that the hole can be placed peripherally (Figure 8-3). Administration of pilocarpine can temporarily give symptoms of a headache or brow ache.


Figure 8-3. Pilocarpine HCl 2% solution. Pilocarpine (a cholinergic agent) constricts the pupil prior to creation of a peripheral iridotomy.

In instances of acute angle closure glaucoma, the cornea may be too swollen and hazy which precludes a good view of the iris (see Chapter 9). Prompt administration of glaucoma medications, both topical and oral, helps to decrease the IOP. This can reduce corneal swelling and increase the clarity of the cornea. Glycerin is another agent which acts to draw fluid from the cornea and temporarily improve the corneal clarity. Once the view is adequate, the laser procedure can be performed. LPI is done under topical anesthesia. A special iridotomy contact lens (Figure 8-4) is placed on the cornea. The laser is then performed through the contact lens. After the procedure, another glaucoma medication is given. An IOP check is performed 1 hour after the laser treatment. Topical steroids are given for several days and then tapered or discontinued. This helps alleviate any inflammation from the laser. The inflammatory cell and pigments released during iridotomy may cause decreased vision after the laser, but this typically subsides in 3-4 days.

Laser Iridotomy contact lens

Figure 8-4. Laser Iridotomy Contact Lens. This lens allows a magnified view of the iris architecture for laser peripheral iridotomy.

The LPI will relieve IOP elevation resulting from acute angle closure glaucoma (see Chapter 9). In cases of narrow, occludable angles with normal IOP, it will prevent acute angle closure from occurring in the future. Once the iridotomy is made, it remains open and the risk of acute angle closure glaucoma is eliminated. Even with patent iridotomy hole, patients may still develop IOP from other mechanisms. These patients are sometimes referred to have mixed mechanism glaucoma. The mechanism is mixed because there is a component of both closed and open angle contributing to the development of glaucoma.

Complications of LPI

The most frequent complication of LPI is a transient IOP increase. It is uncommon due to do the use of pre- and post-laser glaucoma medication (e.g. brimonidine). Ocular inflammation, or iritis, may also develop. This is treated with a short course of topical steroids. Ongoing inflammation may sometimes cause closure of the iridotomy site. Corneal or lens damage may occur with the laser treatment due to the proximity of these structures to the peripheral iris. In addition, retinal damage from the laser may rarely occur. Bleeding can occur during the LPI when iris blood vessels are disrupted during the laser procedure. It can be managed by applying gentle pressure with the iridotomy lens, or by simply waiting until blood coagulates on its own. Although rare, a significant amount of bleeding in the anterior chamber may cause the IOP to increase. Rarely, patients may complain of double vision (diplopia) or seeing a line in their vision. These visual aberrations may be from the iridotomy hole itself. The symptoms are often transient and become less noticeable over time.


Blogger Tom said...

For anyone interested, here's a video of a laser iridotomy being performed (using all the equipment and techniques mentioned here):

Laser Iridotomy Video

In this case, a YAG laser is being used. The key is to find an iris crypt that is already somewhat thin. You deepen the entry until you get a gush of fluid from the posterior iris coming through ... you can see this in the video.

7:46 AM  
Anonymous Anonymous said...

this video shows an iridotomy which is called safe with rare complications.
Recent studies have shown, however, that these complications are frequent. About 65% of the patients can no longer drive after having undergone an iridotomy, and about 42% have to give up their job because of diplopia, glare, loss of visual acuity and other severe visual impairments.


1:07 PM  
Blogger Tom said...

Your statistics are simply not true. Please support them with a reference.

In my experience having actually seen iridotomies performed and seeing these patients for years, I have never experienced a patient who couldn't drive after an LPI. Nor have I seen a patient have to give up their job after an LPI.

However, I HAVE seen a patient lose their vision because they DIDN'T get an iridotomy.

Remember, 64% of statistics are completely made up! Your numbers don't make sense.

5:44 PM  
Blogger MedRounds Publications said...

Response from Young H. Kwon, MD PhD:

Laser peripheral iridotomy is a necessary procedure to prevent pupillary block and acute angle closure glaucoma. Whenever a surgical or laser procedure is performed, potential benefits should be carefully weighed against potential complications.

When the iridocorneal angle is sufficiently narrow to put the patient at high risk for developing acute angle closure, laser iridotomy is warranted. At University of Iowa, we perform 1 to 4 laser iridotomies per week. The most common side effect is iritis or bleeding, which is transient and clears within a few days with treatment. Infrequently, it is associated with post-operative elevated intraocular pressure. It is possible, but rare, for people to develop double vision or other visual complaints post-operatively. It is thought that the location of the laser iridotomy may be a contributing factor.

It has NOT been our experience that 65% of the patients no longer drive or 42% of them give up their jobs due to visual impairment after LPI. In our experience, such outcomes are exceedingly rare.

4:56 AM  
Blogger MoMan said...

I had a LPI in October of 2006 at the Duke Eye Center. This procedure was performed by Dr. S Asrani and I have had no complications. The surgery was quite painful about 2 hors later on my drive home.

8:18 AM  
Anonymous MDIM said...

Had an LPI done today 9/26/08 and I am fine. I fully plan to drive and work! What rubbish Henry comment is above! Lord, stop scaring people. This is a perfectly safe procedure and I am having the next eye done next week. I would not want my angles to close and lose my vision. I am glad I had this option!!!! Medical Technology is a great thing!

12:32 PM  
Anonymous H said...


How is it going? My mother is scheduled to have this done on Monday (10/6/08).

Thanks in advance and hope you are well.


7:24 PM  
Blogger Pete said...

Had mine done last week in Oldham,England and it went as expected.Sadly I was initially wrongly given eyedrops that made my pupils bigger not smaller.Different drops then corrected this and I could then have the procedure done.In my case I had 11 "zaps" in my left eye and 12 in my right.None of them particularly hurt and reckon I was back to my normal vision within 2 hours.
Good luck to those who are still to have the procedure performed.

5:06 AM  
Anonymous Anonymous said...

I had my procedure done to both eyes. For some unknown reason, the procedure had to be done twice in my right eye and three times in my left eye. The first time it was done, if I had not gone back to the doctor and ASK for a followup check up, they would had not known that the first hole got blocked with some pigmintation and they had to zap it again. Same with the left eye where it got blocked twice and they zapped it for the third time. Now I see a hoizontal line thru my right and left eye which can not be corrected. I will be going to see another eye doctor to find out if the procedure was done incorrectly or if this is the out come for some patients.

9:47 AM  
Anonymous Anonymous said...

I am 50 years old, and will be evaluated soon to see if the doctor recommends this procedure as a preventive measure. Both my father and his mother had glaucoma in their 60s. Where can I find RELIABLE statistics about the incidence of complications resulting from this procedure?

12:22 PM  

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