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What Is Canaloplasty?

What Examination Does a Patient Need to Undergo in Order to Determine the Scarring of the Canal?


All ophthalmologists are trained to perform gonioscopy but few have the experience to state whether canaloplasty would be an option.


Warm regards,
David Richardson, MD

Date: Jun 17, 2013



Is the Canaloplasty Procedure a Mere “Marketing Concept”?


Hello David;

Sorry it has taken a while to get back to you. I did receive my records but upon referral of my PCP, I wanted to see another ophthalmologist to get a second opinion regarding whether or not I needed a trabeculectomy. Mainly this was because of my insurance / financial situation. The other Dr told me that based on his examination I fell into the moderate category of severity of glaucoma. He felt that the trabeculectomy would be a better solution since 90% of my optic nerve has been damaged and my remaining 10% no longer consists of that redundant tissue. If I were in the mild category then a canaloplasty would seem to be a better choice, but my condition is one of exigency he implied.

I know that we have discussed the attitudes of ophthalmologists who won’t perform canaloplasties because of skill and they feel that it is a fad. In fact, he had mentioned that such a procedure is a “marketing concept” and also it takes away a lot of “real estate” of the eye (whatever that means) if further procedures were needed to be done. I had mentioned to him the post op complications associated with trabs, and especially that fact that I am African American, from which such a surgery has the least effectiveness; but his response was the likelihood of that happening to me is not that great and the surgery failing is decreased if I take the proper steps in my post op care. Unlike the other doctor, he spent a great deal of time with me and was willing to try a different combination of medications / minimally invasive procedures to lower my pressure despite his feelings that the trab surgery would be in my best interest.

The most frustrating thing of all this is not so much the disease or the surgeries, but the fact that in the medical community there is a wide gap between those who espouse a certain procedure over the other. You have the canaloplasty surgeons on one side of the fence and the trabeculectomy surgeons on the other with the patients caught in the middle. There seems to be no collaboration on procedures that give us patients a “good feeling” about which direction to take. This has been my experience. He, like other doctors state that the trabeculectomy is the “gold standard” and eliminates all doubt of pressures going back up again in contrast to the other surgeries. He also stated that a canaloplasty was NOT a minimally invasive surgery. So with all the other options on the table, like the shunts, trabectome etc., which he stated are possible, it seemed as if they, along with canaloplasty would simply prolong the inevitable and I would be subject to a trabeculectomy anyway, so why not just cut to the chase? That’s what I got from him.

Anyway, I wanted to keep you in the loop. Please feel free to add your thoughts.




Dear ******,

I also find it sad that most eye surgeons have taken a position on canaloplasty without making the effort to first become adept at it. Then again, it is a difficult surgery to perform so not everyone is capable of mastering it. Perhaps that is what lies behind much of the debate as no surgeon likes to face the idea that there are some surgeries that they might not be able to master.

One of the greatest living glaucoma surgeons, Dr. Robert Stegmann, developed viscocanalostomy as well as canalopalsty and just published a paper showing great 12-15 year results with the less effective viscocanalostomy:

Canaloplasty can on average achieve an IOP 2mmHg lower than viscocanalostomy:

If canaloplasty is a “marketing concept” then it’s failed to succeed in converting surgeons to do it. Dr. Stegmann is a smarter and better surgeon than I. He created canaloplasty to meet a desperate need of treating glaucoma “in the bush” (his words). To whom was he marketing? His patients had no money. Alternatively, if canaloplasty is a fad, it’s a long-term one and will likely be replaced only by better canal-based surgical techniques.

How Long Has Canaloplasty Been Around?

Now, to address some of the other issues mentioned:

“it [canaloplasty] takes away a lot of “real estate” of the eye (whatever that means) if further procedures were needed to be done.”

This is a common, but unsupported, concern among surgeons who do not perform canaloplasty. This issue has been addressed in the literature. Trabeculectomy success was the same whether or not canaloplasty was performed prior to trabeculectomy:

Trabeculectomy Glaucoma Surgery After Canaloplasty


“I had mentioned to him the post op complications associated with trabs, and especially that fact that I am African American, from which such a surgery has the least effectiveness; but his response was the likelihood of that happening to me is not that great and the surgery failing is decreased if I take the proper steps in my post op care.”

Interesting response. Perhaps he has discovered the “secret sauce” of trabeculectomy that other skilled and respected glaucoma surgeons have been searching for. Many glaucoma surgeons, however, will admit among themselves that what they hate most about trabeculectomies is that the surgery can go perfectly yet the final outcome cannot be predicted for any individual patient.

“He, like other doctors state that the trabeculectomy is the “gold standard” and eliminates all doubt of pressures going back up again in contrast to the other surgeries.”

Trabeculectomy is the “gold standard” for the reasons I outline here:

Why Trabeculectomy is the Most Common Glaucoma Surgery

Yes, it is the most likely procedure to achieve a low IOP with or without drops. And, it may very well be the best option for you. However, there is a definite risk/reward relationship. You can’t get the single digit IOPs off drops without taking a significant risk. Not everyone, however, needs IOPs that low. Do you?

“So with all the other options on the table, like the shunts, trabectome etc., which he stated are possible, it seemed as if they, along with canaloplasty would simply prolong the inevitable and I would be subject to a trabeculectomy anyway, so why not just cut to the chase?”

Why? Because no glaucoma surgery can be expected to last a lifetime. Do you plan on living for another decade or two or three or…? Then you had better plan on having multiple surgeries for your glaucoma. Might your surgery (canaloplasty or trabeculectomy or something else) last for your lifetime? Sure, it happens. But it’s not to be expected.

Failure rates for trabeculectomy average 10-15% per year with 50% having failed by five years after surgery. These are the rates of published surgeons (probably the best of class). Some have estimated that rates of failure in the community may be even higher.

Canaloplasty is likely to fail at the same rate. So why chose canaloplasty first? Because it’s the safer option and if it doesn’t work (or eventually fails) you can still go on to either a trabeculectomy or glaucoma drainage device (tube).

The question I’d ask is “Why close a door on a safer procedure if you don’t have to?”

Not having examined you in person I don’t know whether you are even a good candidate for canaloplasty. If you do go ahead with trabeculectomy (which, again, for all I know may be the most appropriate option for you) then having trabeculectomy performed with an Ex-PRESS mini-shunt will at least make it easier to perform canaloplasty down the line if (when?) the trabeculectomy fails. Yes, canaloplasty can be performed after trabeculectomy but it’s exponentially more challenging (for a surgery that’s challenging to begin with). At least with a properly placed Ex-PRESS shunt the canal is left intact making canaloplasty only moderately more challenging to do.

A significant limitation of basing an individual decision on probabilities is that you’re not a population, you’re an individual. Ultimately you will chose a surgery and it will either adequately lower your IOP or it won’t. If it doesn’t you move on to the next treatment option. It just makes more sense to me (and I’m the first to admit that not all surgeons agree with this) to start with the lower-risk options and scale up to higher risk only when the lower-risk options fail.

I don’t know whether this was of help to you or not. My hope is that whatever surgery you choose will succeed for many years and do so with no complications. I am also hopeful that once you make your choice you will enjoy peace of mind that it was the “right” choice for you whether it succeeds or not.

Glaucoma surgery is a bit like the “Let’s Make a Deal!” show. You simply won’t know whether you chose correctly until the curtain is lifted (you’ve healed from surgery). There’s no point in berating oneself if the chosen surgery doesn’t work as expected because there are no guarantees.

Worth emphasizing is that no currently available surgery or surgeon is capable of eliminating “all doubt of pressures going back up again in contrast to the other surgeries” even if you “take the proper steps in [your] post op care”.


Warm regards,
David Richardson, MD

Date: Oct 15, 2014



I Had LASIK and Iridotomy on Both Eyes. Is Canaloplasty Suitable for Me?


Dear Ana, thank you for your email. My name is ******. I’m from Indonesia. I’m 40 year old. I found Dr. Richardson website just one day before my trabeculectomy operation. I have canceled the operation and want to find out whether canaloplasty suitable for me.

I have my LASIK in both eyes in January 2010. Before have LASIK my eyes are -5 ( right eye ) and -7 (left eye). The doctor saw my high IOP in both eyes and retinal tears in my right eye. The IOP was at high twenties. After have glaoplus (local name for xalacom), my IOP was stable at 10 – 12. And after retinal laser, my retinal tears problem in the right eye is solved.

Several months after LASIK, my IOP started to elevated again to high twenties. My Doctor who is glaucoma specialist gave me xalacom 1 drop per day in both eye, and my IOP stable at 9 – 11. It lasted for 1 year, when my doctor told me that my high IOP controllable and he will reduce the dose. And suddenly my doctor ask me to stop using xalacom and change to alphagan 3 times drop a day. After using alphagan, I feel pain in my eyes and my IOP rose to high twenties. My Doctor gave me alphagan and azopt, both 3 times a day, no improvement. My Doctor gave me alphagan, azopt and xalacom, still no improvement at all. Quite strange, because previously xalacom worked well to my eyes. My docter gave me alphagan, azopt and duotrav, and it worsening. At that time my IOP rose to high thirties to low forties. After that my doctor recomend laser therapy for my eyes, but I refused.

I switch to other glaucoma specialist, the same cycle is happened again. I started with timolol, glaoplus (local name for xalacom), alphagan, azopt, and at the end my second doctor recommend me for trabeculectomy. I refused. My IOP was still at high thirties and low fourties.

Without advice from doctor, I tried phylocarpine 1%. I worked well, especially for my right eye. The IOP for the right eye could drop to 15. But it seem not affected my left eye. My left eye IOP was still high twenties to low thirties. I can only use phylocarpine at night before sleep. If I use at the other time the result is not that good.

Six month ago I diagnosed hyperthiroid, and still in medication right now. Quite interesting, during early period of hyperthiroid, my eyes improved very very well, even without eye drop. But after got hyperthiroid medicine, my eyes condition back to pre hyperthiroid condition.

I switch to the third glaucoma specialist, and she recommend me iridotomy. Before take the iridotomy I use brimodine (similar to alphagan) 2 times a day and glaucon (local brand for diamox) three time a day. At the iridotomy day, my IOP was quite good, 12 for right eye and 15 for the left eye.

After iridotomy, the IOP rose to mid thirties and low forties. The glaucoma specialist recommend me for trabeculectomy. I try using pylocarpine (which previously succes to bring down my IOP to fifteen), but this time was unsuccessful. My IOP is still high thirties to low forties. I am tired, hopeless and agree to have trabeculectomy.

As I said before, I found Dr. Richardson website, and wondering if it suitable for me. I quite rational, the broken nerve cannot be repaired and I do not expect my vision back to normal. I just want to maintain my current optical nerves at lowest risk possible, which I expect from canaloplasty.

You can find my humprey test as attached.

I also cc my email to my sister. My sister already has US visa, but I still don’t have it and try to get it.

While waiting for my US visa, do you have slot for canaloplasty, let say in January 2015?

Btw, my phone number is ******. But because of my english is not that fluent, I prefer using email, because I can think before talk to you.

Thank you


Hello ******,

Ana forwarded your email to me. I would be happy to evaluate you and (if you are a candidate) we could schedule canaloplasty for January 2015. If you think this is something you would like to pursue please let Ana know so that she can block out some time for your possible surgery.

Without examining your eyes I cannot determine whether you are, indeed, a candidate for canaloplasty. If your angles are open then canaloplasty can be expected to achieve adequate IOP lowering about 85% of the time[1] .

I am concerned, however, that another doctor recommended peripheral iridotomy (PI). This is generally only recommended with narrow angles or pigment dispersion syndrome. If your angles are narrow then canaloplasty alone would not be indicated (though it might be reasonable at the time of cataract surgery). If the reason for laser PI was pigment dispersion then canaloplasty could be a reasonable surgical treatment option.

Hoping this was helpful.

Warm regards,
David Richardson, MD

[1] Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg. 2011;37(4):682-90.

Bull H, von Wolff K, Korber N, Tetz M. Three-year canaloplasty outcomes for the treatment of open-angle glaucoma: European study results. Graefes Arch Clin Exp Ophthalmol. 2011;249(10):1537-45.

Brusini P. Canaloplasty in open-angle glaucoma surgery: a four-year follow-up. ScientificWorldJournal. 2014;2014:469609.

Date: Friday, December 26, 2014 10:47 PM


Underwent Surgery Twice, Is Canaloplasty Still Possible?


Hi, Sir I’ve heard a lot about you as a glucoma specialist. I have glaucoma for five years already on my left eye. I’ve underwent surgery twice under the same doctor, Dr ******. So, please help me on the treatment. Also, please send me your email address so we can talk easily and you can help me

P**** (from India) via Submit Form


Hello P****,

I’m sorry to hear about the difficulty you are having with your left eye. Unfortunately, I doubt that canaloplasty would be effective if you’ve already had two surgeries on the eye. To the best of my knowledge, Dr. Ganesh Venkataraman at the Aravind Eye Hospital performs canaloplasty. I recommend that you contact him as there is very little I can do by email. An in-person examination at the clinical microscope is needed in order to determine what treatment would be most appropriate for your eye.

Warm regards,
David Richardson, MD
Adjunct Assistant Professor of Clinical Ophthalmology
USC Roski Eye Institute
Keck School of Medicine of USC

San Marino Eye
2020 Huntington Drive
San Marino, CA 91108

Patient-Focused Websites:


What Is the Big Deal About Bleb Anyway?


One of the benefits of canaloplasty is that it’s essentially a bleb-free procedure. It’s rare for anyone to develop a bleb. Almost everyone after canaloplasty is able to wear soft contact lenses if they desire, is able to continue with their activities including water sports once the eyes is healed up. And in general, dry eye or ocular surface disease is not only “not made worst”, but in some cases is better after canaloplasty because patients are not using as many drops after the surgery.


Warm regards,
David Richardson, MD

Date: Aug 29, 2013



What If My Natural Drainage Canal Cannot Be Fully Catheterized?


To get the full benefit of Canaloplasty, it is important for your surgeon to fully catheterize your natural drainage canal. Once that’s done, your surgeon can then dilate the canal just as with angioplasty. And following that, leave a stent in the canal which leaves it open after surgery. If anyone of these steps cannot be fully performed, then the effect of the surgery can be reduced. That being said, even if a stent cannot be placed in the canal, a recent study has shown that the pressure lowering effect can still be good, if not as good as Canaloplasty with stent. Also, your surgeon does have the option at his or her discretion of converting to a more traditional glaucoma surgery such as Trabeculectomy if he or she feels that that’s appropriate.


Warm regards,
David Richardson, MD

Date: Aug 29, 2013



Why Perform Canaloplasty as a Primary Glaucoma Surgery?


One of things I find most frustrating about glaucoma is that, in the early stages it’s a disease without symptoms. So just like high blood pressure, diabetes, we as doctors end up treating a condition that has no symptoms and the treatment itself results in worsening symptoms. Take for example drops. Drops can be irritating, worsen dry eyes, they’re expensive and sometimes they can even have significant systemic side effects. As a doctor I find it difficult to treat a symptom free disease, with something that results in symptoms. Also the traditional glaucoma surgeries have significant risks associated with them. And it’s very difficult for me to recommend a surgery that has a significant risk of loss of vision, to somebody who currently, may not have notable loss of vision. Canaloplasty really hits that sweet spot for me. It’s a lower risked surgery that can actually reduce the symptoms of other treatments such as drops. So combining this safety profile, the low symptom profile and a condition which starts of symptom free, I really find that canaloplasty meets the needs of not only me as a doctor looking out for the protection of my patients vision, but also the needs of my patients.


Warm regards,
David Richardson, MD

Date: Aug 29, 2013



Will Canaloplasty Cure My Glaucoma?


Today there are no cures for glaucoma. Both drops and surgeries work to protect your vision from further loss of vision by lowering the pressure in the eye. Now, one of the advantages of surgeries such as canaloplasty is that there’s mountain of evidence that the pressure stays low throughout the day. Whereas with drops there can be quite a bit of fluctuations during the day. Additionally, canaloplasty has the added advantage of restoring your natural drainage system and opening it up so that it can work the way it used to before you developed glaucoma.


Warm regards,
David Richardson, MD

Date: Aug 29, 2013



Is Success an Assured Outcome with Canaloplasty?


Dear Dr Richardson,

Thank you for your usual prompt response.

I have attached the reports on the ‘visual fields’. Hopefully that does not change your view on what can be done.

Based on the information you have is success a assured outcome and of course the definition of success (i.e: is that to stop deterioration).

Much appreciated,



Dear Mr. ******,

Thank you for sending the visual field printouts. Fortunately they do not impact my sense that Mr. ****** would likely be a candidate for Canaloplasty.

With regard to anticipated outcome, no available glaucoma treatment is successful 100% of the time. With Canaloplasty one can expect to achieve a satisfactory reduction in IOP (with or without drops) in about 85% of those who undergo the procedure. This is similar to what can be expected with trabeculectomy (¨trab¨) or glaucoma drainage devices (¨tubes¨). All glaucoma surgeries also have a rate of failure. In the case of trabs and tubes one can expect about 50% to fail over the first 5 years. Canaloplasty alone appears to have a similar failure rate except that when it is combined with cataract surgery that failure rate drops in half. In general, when Canaloplasty is combined with cataract surgery one can expect both better IOP control and longer-term success.

The main benefits of Canaloplasty over trabeculectomy and glaucoma drainage devices are safety, lack of significant lifestyle limitations, and faster recovery. For example, trabeculectomy can significantly worsen dry eye syndrome which can be quite bothersome (even disabling) in someone who works in a hot, arid environment or must spend hours working on the computer or paperwork. After Canaloplasty, on the other hand, dry eye symptoms are only transiently worse and often improve compared to pre-operative experience.

I find it helpful to think of all glaucoma surgeries in terms of ¨What would be my next option if (when) this surgery stops working?¨ Yes, it is possible to have only one glaucoma surgery and have it work for life. The statistics, however, do not make that a high likelihood. Another benefit of Canaloplasty is that both trabs and tubes can be performed after Canaloplasty. The opposite, however, is not true. Canaloplasty is technically quite challenging after a trabeculectomy and may not be possible at all after a tube (unless the tube is actually removed from the eye). As such, a reasonable step-wise progression would be Canaloplasty -> trabeculectomy -> tube or even Canaloplasty -> tube -> second tube. By performing Canaloplasty first one is choosing to undergo the safest of the three glaucoma procedures with future options still available (if necessary).

I hope this was helpful.

Warm regards,
David Richardson, MD

Date: Wed, Feb 18, 2015 at 5:48 AM


Upon Arriving in the US, How Long Should I Rest Before Having Canaloplasty?


How long should I take a rest after arrive in US before having canaloplasty?


There’s no question that you’ll take longer to recover from the effect of the anesthesia if you are still jet-lagged. Ideally you would have a few days to recover from jet lag before surgery. Given that you are arriving in the USA on the 22nd that would make Monday, January 26 a good day for surgery.

Warm regards,
David Richardson, MD

Date: Thu, Jan 15, 2015 at 1:53 AM


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