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October 2005

 
Clinical Update: Oculoplastics
Intracanalicular Plugs: Use With Caution
By Marianne Doran, Contributing Writer
 
 

Lacrimal plugs can be a godsend for dry eye patients whose symptoms aren't well controlled with artificial tears or ocular lubricants. But that relief can turn to misery if a plug migrates deep into the lacrimal system, blocks lacrimal outflow and causes overflow tearing or infection. Intracanalicular plugs are the primary culprits, although occasionally an external plug inadvertently may be pushed down into the canaliculus during insertion.

Although plug migration doesn't happen often, when it does it can send some patients on an uncomfortable and frustrating odyssey of multiple surgeries to retrieve the plug and repair the damage left behind. Oculoplastic surgeons are the ones who see that damage and are left to try to fix a problem that might have been avoided.

Because intracanalicular plugs are so easy to place and only a small percentage of the plugs get stuck, it's easy to just reach for them and put them in, said John W. Shore, MD, an oculoplastic surgeon with Texas Oculoplastic Consultants in Austin, Texas. But for people who do have one that becomes stuck, it's a huge problem. In some patients the tear duct is totally destroyed, and you have to resort to an artificial tear duct.

Why the Complications
Michael J. Hawes, MD, clinical professor of ophthalmology at the University of Colorado Health Sciences Center in Denver, described how patients end up in his office for surgical removal of a plug sometimes after consulting two or three other doctors. Patients typically start with a dry eye problem, have the device placed to get more moisture on the eye, and it works initially. But after a certain interval maybe a year later the eye becomes too wet, and tears run down their face or well up by their eye.

Hidden trouble. Several factors contribute to potential complications with intracanalicular plugs. The most obvious is that you can't see them once they are in, making it difficult to manipulate the plugs or even to locate them. Moreover, although the plugs are billed as being easily removed, that's not always the case.

The idea was that you could push the plugs in, and then if you didn't need them anymore, you could somehow push them through with a little instrument or flush them out with some hydraulic pressure generated by a syringe and a blunt-tipped needle, Dr. Shore said. The problem is that in some patients the anatomy of the inside of the tear duct prevents the plug from exiting where it is supposed to.

Plugged or unplugged? William L. White, MD, associate professor of pediatrics and ophthalmology, Children's Mercy Hospital, University of Missouri-Kansas City, noted that when you try to squirt a plug out or down into the nasolacrimal duct, you never really know if it's gone. That makes it difficult to assess a plug's efficacy and can lead to repeated plug placements. If a patient doesn't respond to one plug, some people presume it's gone downstream, and they put in another plug or two or three or four, he said. That just makes this bezoar of material that can collect in the lacrimal sac and cause dacryocystitis or lacrimal outflow infection.

These infections and the formation of scar tissue around a plug can cause obstructions and make retrieval difficult. Dr. White noted that the pathophysiology of these occlusions isn't fully understood. We think that when the plug is placed, a reservoir of stagnant tears is left in the upper portion of the canaliculus, and you have a pond for bacteria to grow in, he said. The subsequent inflammatory process makes it so that you can't irrigate or probe the device out of the nasolacrimal duct.

Tearful development. If the obstruction completely blocks outflow, a patient's dry eye problem can become a tearing problem that is even more disruptive to their lives than having dry eyes. You can have a patient with dry eye which may or may not have been symptomatic who has a device placed that is supposed to improve the problem but actually creates a new problem, Dr. White added.

Educate the patient. So far, there is no reliable way to predict which patients might be at risk of having a retained plug and overflow tearing. However, Dr. Hawes noted that he sees the problem most often in patients who have had LASIK or another refractive procedure probably because they tend to receive more of the plugs.

Patients also need to be better educated about plugs and what type was put in. Some don't even recall having a plug placed, and plugs are often found unexpectedly during surgery to open a blocked tear duct.

I've found that patients are not well informed about this device that is being put in, Dr. Shore said. It's like having an implant, but they don't have anything in their wallet that says what kind of plug was put in, whether it was intracanalicular or external, or where it was placed. An informed patient is important because without diagnostic tests to verify and locate a retained plug, patient history and probing are all a surgeon has to go on. All you know is that a tear duct is blocked, Dr. Shore added. If the patient tells you a plug was placed, you can strongly suspect it, but you don't really know until you go in.

Surgical Retrieval
Dr. Hawes noted that he usually finds wayward plugs right at the common canaliculus. To get the plug out, most often I have done a dacryocystorhinostomy, and when I open the lacrimal sac I see the plug at the common canaliculus. Other plugs have been in the canaliculus, and I have sometimes been able to get at them by cutting the canaliculus and fishing them out that way.

Dr. Shore said that when a plug lodged in the midcanaliculus is surrounded by scar tissue, he has had to use silicone tubes to stent open the tear duct while it heals. If the scarring is severe, repair may not be possible. In these instances, if the patient's tearing is intolerable, an artificial tear duct will need to be created. In Dr. Hawes practice, about 15 percent of the patients referred to him for plug removal have irreparable damage that necessitates placement of a Jones tube.

Not a Permanent Solution
Dr. Shore believes that much of the problem with intracanalicular plugs relates to how some ophthalmologists and optometrists view them. Too often, they consider the plugs to be a permanent solution to a patient's dry eye problem instead of a temporary treatment. They put the plugs in with the intention of leaving them in forever. But the patient's situation may change. Patients can move to a different climate or start forming more tears. Their dry eye may have been related to LASIK, and the reflex loop that causes a diminished tear flow after LASIK gets fixed and nature takes over. Suddenly you have an overflow situation with a plug that you can't get out.

First try external plugs. Dr. Shore doesn't use intracanalicular plugs, and said he takes a staged approach using external plugs. He places the external plugs on a temporary basis, never occluding all four ducts at once or putting two plugs in on one side. After some time, if patients are tolerating the temporary occlusion well, he has them decide whether they want to keep the external plugs or elect for surgical occlusion. He added that there are ways of surgically occluding a tear duct that would make reversal possible if the patient develops tearing.

Take-home message. These oculoplastic specialists who see what can go wrong emphasize the importance of a thorough patient assessment and a full discussion of all the treatment options for dry eye. Dr. Shore recommends using an external plug first if at all possible to see if the patient is going to have tearing.

For patients who choose to have an intracanalicular plug placed, full informed consent is essential. This includes a frank discussion of possible complications with the plugs and the option of undergoing a reversible surgical occlusion procedure instead. Patients should be properly informed that placement of an intracanalicular plug can permanently scar the tear duct in an irreversible way, Dr. Shore said. The percentages are small, but if something happens, patients are extremely angry that they weren't told of the risk.

Dr. White added, We want patients who are going to have the device placed to understand what the stakes are before they go in. They need to know that there is a low incidence of irreversible lacrimal outflow occlusion that may subsequently require surgery.

The main thing is that we want to introduce some caution and not just have people throw these things in indiscriminately and create problems down the road, Dr. Shore emphasized. It's like anything else in medicine: It has to be the right patient and the best product they can possibly have and every patient is different.