Is Canaloplasty Worthwhile?

February 28, 2009

Have you seen the videos for this procedure?  I think I’m a decent surgeon, and I don’t like trabeculectomy any more than the next guy, but that looks hard and tedious. Sounds to me this procedure is strictly for the glaucoma guys. And I still think that since I only take the sickest eyes to surgery (as I can control the vast majority with drops, laser and straight phaco), I don’t think this procedure will reliably get my patients down to 12 like a trabeculectomy. So it looks like we are still stuck with trabs. I heard of a promising procedure that creates a nice bypass to the suprachoroidal space using a very small shunt device that is implanted into the angle after you finish the phaco. No bleb! No touching of conjunctiva! Nice!




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34 Responses to “Is Canaloplasty Worthwhile?”

  • Dr. Patel

    Thank you for the forum to discuss current topics, it is a shame that certain people would take advantage of it. My former iScience rep from the Midwest said AB is actually an iScience rep in the west named Adam Bernstein. If you read this thread closely it sounds like a sales pitch. With all due respect to Dr. Richardson, he is a paid consultant to iScience, I heard him speak in Hawaii. It’s interesting how consultants speak so positively and have such great data until they are no longer consultants. I am from the Midwest and first heard about CP 4-5 years ago from Tom Samuelson and Ike Ahmed who were extremely high on the procedure. They are both well known and respected Glaucoma specialists who rarely do the procedure any more, if it is that good you need to ask yourself why? More importantly the company talks about all the doctors they have trained and cases they have done but they never talk about the number of doctors that continue to perform the procedure on an ongoing basis. I heard for the Midwest rep they have trained in excess of 500 doctors and less than 10% continue to do the procedure. Maybe Dr. Richardson or AB can get the company to respond on this blog how many of those doctors continue to perform the procedure after they get through the learning curve. It would also be interesting to see how many are doing the procedure regularly, at least two a month and are not paid consultants. If the numbers are good I am sure they would be happy to share them in this blog and prove my intuition wrong. I personally know six doctors well who were trained in the Midwest who each did between 15-50 cases, none of whom are doing Canaloplasty any longer. They are all good surgeons (better than me) but none of them could get the low pressures routinely that doctor Richardson talks about. They might get them to start off that low but most crept up over time to the high teens, pressures we can get quickly and easily get with ECP. Bottom line if Canaloplasty was as good as presented in this blog, a majority of the people trained would be doing it routinely and I have never heard data to support that case.

  • Dr. Ari Weitzner

    but what choice do you have if you want to control the pressure?

  • Dr. Soraya Lingbeek

    Dear Sirs and Madam,

    my mother has secondary glaucoma resulting from bleedings due to her previous AMD. The eye is already blinded before from the AMDE bleeding. The surgeon would not want to take the risk of a new vitrectomy.

    Since medications don’t help a lot, she is extremely stressed and traumatised, the doctors started with paracenthesis to evacuate the blood. The main benefit that we are seeking for is reduction of the IOP(difficult to control with meds) and all the symptoms of dizziness and pain. We are afraid of re-bleeding and the surgeon suggested trabulectomy which is for sure risky esp. for a stressed out person like my mother.


  • Very interesting and detailed thread. Since my earlier post over a year ago, there are a few comments either Ari or I made that I think are worth addressing:

    – “I don’t think this procedure will reliably get my patients down to 12 like a trabeculectomy.”  – Ari

    I’ve just reviewed my first 125 cases and on average my patients s/p canaloplasty are in the range of 12-13mmHg whereas my phacocanaloplasty patients are hovering around 11-12mmHg (and 87% of the latter are off ALL drops). I have not yet performed the standard deviation analysis but plan to do so prior to the AAO meeting in the fall.

    – Previously I had performed canaloplasty on my open angle patients “except those who are end-stage.” – me

    This is no longer the case. I now feel that canaloplasty is a better procedure for end-stage glaucoma then either tubes or trabs because the risk of snuffing out the optic nerve secondary to extreme IOP elevation simply doesn’t exist. If the IOP does not reach the target then either drops or going on to another procedure (such as ECP, trab, or tube) is still an option. Why take the risk of a trab or tube when you could more safely reach your goal with canaloplasty?

    – “an iop of 9 is very uncommon with canaloplasty” – Ari

    Not really. I’ve been pleasantly surprised at how many of my patients are hovering between 8-11mmHg (off drops). The difference is that NONE of my patients (after the first week or so) are below 7mmHg – I simply have not seen hypotony maculopathy in any of over 140 cases.

    – “major drawback- it involves the conjunctiva, so if one needs a trab later, the conj manipulation will make success much less likely” – Ari

    That would have been my assumption also, but it just doesn’t seem to be the case.

    First, canaloplasty can be done in a quadrant (though a bit more challenging than at 12:00). This leaves a remaining superior quadrant available for the 3% who go on to another surgery. How many other surgeries would we “poo poo” because 3% of the time it might fail or be difficult to perform another surgery later? Cataract surgery? Nope. Published rates of failure range in the 3-5%. If this argument were applied to phaco no one would be doing cataract surgery. LASIK? Right. 100% of patients with LASIK (unless they meet their maker first) are going to need cataract surgery and be a PITA for the surgeon who will have to correctly target the IOL in a demanding patient with unrealistic expectations. Let’s be honest with each other – the argument that canaloplasty might limit the ability to perform a future trab is a red herring (an convenient excuse for those who don’t want to try it).

    Second, when you look at the conjunctiva in a patient who has had canaloplasty it is remarkably normal in appearance. Often the mobility and lack of injection (a few months out) appear to be no different than that of the uninvolved quadrant. There is no scarring down of the conjunctiva to the underlying sclera as there is with scleral tunnel cataract surgery. Why I can’t tell you, but other than visualizing the scleral flap these patients have conjunctiva that often looks and acts normal at the slitlamp. I can’t see any reason why this would limit the ability of a decent trab surgeon from attempting to perform a trab in that quadrant if s/he needed to do so (but why s/he would when there is an untouched quadrant is beyond my understanding).

    Bottom line is that I now feel strongly that any patient who is a candidate for trabeculectomy should be given the option of canaloplasty first. We’re not there yet, but I envision a time when (similar to advising cataract patients about their IOL options) it will be considered below the standard of care to go straight to trab without at least having a discussion with the patient about his or her blebless options. Why do I feel this way? Because I now get a regular stream of patient who have had “successful” trabeculectomy in one eye and are “pissed off” at their prior glaucoma surgeon for “doing this to me.”

    My patients’ words have brought me to the conclusion that trabeculectomy is something we do “to” our patients. Canaloplasty, on the other hand can be said to be something we do “for” our patients. If this seems controversial, it is only because you (not you, Ari, but “you” the reader of this thread) have not had your own canaloplasty patients with which to compare with your own trabeculectomy patients. Once you have a dozen or so canaloplasty patients in your office you’ll know what I’m talking about.

    I’d be happy to talk to anyone on this forum “off line” if you have concerns or questions about canaloplasty that you are not comfortable asking online.


  • ab

    That’s wonderful, I would suggest calling iScience to ask about wet lab opportunities

  • ari

    you have inspired me to seek out a wetlab! thanks! does istent conduct them?

  • ab

    All of the ‘easier’ procedures that are currently FDA approved or on the immediate horizon for approval lower IOP somewhat (not to the same degree as Canaloplasty) but the med count is virtually unchanged. Canaloplasty patients more times than not will ASK for the procedure on their other eye. This is not due to the patient being thrilled with their IOP reduction as this is not tangible to the patient (only doctors are fixated on IOP reduction). The reason so many patients request Canaloplasty on their other eye is once they become med free without a bleb on one eye, the patient then notices the extreme difference between their two eyes when there was no understanding prior of how much better their eyes could look and feel. In addition, the patient doesnt have to deal with the daily burden of putting drops in their Canaloplasty eye and associated costs. The manufacturer (iScience) has done an informal study in which over 90% of doctors starting the procedure thought finding the canal would be difficult PRIOR to their wet labs and surgeries (and these were doctors that actually scheduled to start). AFTER their initial wet lab and surgeries, 80% of the doctors thought finding the canal was easy! Based on this study, I would strongly encourage you to try out a wet lab as I would be willing to bet that you will find the canal on your first attempt, realize the procedure is doable, and be able to offer this wonderful procedure to your patients that you would choose for your own eyes. At the very least, I would suggest referring all of your glaucoma patients that are non-controlled or struggling with their meds to a colleague that performs Canaloplasty. I thank you for the stimulating discussion and for being so open minded.

  • ari

    based on the videos i saw, it looked to me that the conj manipulation was very similar to that of trab, and i suspect one would have to operate adjacent to the site- true, not the worst thing in the world. i am surprised that only 3% needed a re-op after canaloplasty- i thought it was higher.
    considering all the pluses and minuses, i have to admit i would prefer the canaloplasty for myself.
    let’s all hope that one of the blebless procedures that are being developed turns out to be effective and easier than canaoplasty! i am still amazed you guys can find schlems canal and are able to cannulate it! i tip my hat to you, sir.

  • ab

    Dr. Weitzner, It is true that whenever conjunctiva is touched it is never the same but i think you are applying how the conj is affected post trabeculectomy to Canaloplasty, which in my opinion is not fair. Canaloplasty affects the conj far less than a trab and most experienced surgeons will say that you could still do a trab in the same location. This is due to Canaloplasty not requiring MMC (which keeps the conjunctiva more mobile). In addition, since there is no bleb with Canaloplasty, the conj avoids continuous exposure to aqueous which is likely to make it microcystic and compromised. If this is still a concern to the less experienced Canaloplasty surgeon, they could always rotate the site of the Canaloplasty procedure leaving space for a future trab. I dont think there is much to worry about anyway as less than 3% of Canaloplasty patients in the FDA clinical study moved on to another procedure.

    Also, I respectfully disagree that Canaloplasty is only for patients with mild-moderate glaucoma. The patient above states that his pressure is 9 and although that is lower than what is typically achieved with Canaloplasty, it does happen perhaps more than people would expect. As a result, why not give a patient the opportunity of a Canaloplasty, (no bleb, much safer, able to continue all activities) versus just automatically giving the patient a trab with all the known risks and quality of life affecting side effects? If very low pressures are required and the patient ends up with a trab, that doesnt guarantee pressures of 9 either. Some trab patients still need meds and other have pressures too low (hypotonous) which could be sight threatening. Unlike trabs, Canaloplasty patients do not get flat chambers even when pressures are very low. I think many doctors and patients would rather have a Canaloplasty plus a med over a trab (especially when a trab doesnt guarantee the patient is off meds anyway). I liked hearing that a patient above chimed in about how much he is happy he chose to have a Canaloplasty. How many trab patients would say they were happy with their procedure? The world famous Ophthalmolgist, Dr. Robert Sinskey chose Canaloplasty for his eye over a trab for many of the reasons discussed above. Dr. Weitzner, I would never hope that you get glaucoma, but if you did, wouldn’t you want to try a Canaloplasty first?

  • ari

    an iop of 9 is very uncommon with canaloplasty. but i agree it’s a nice procedure for mild-moderate glaucoma. major drawback- it involves the conjunctiva, so if one needs a trab later, the conj manipulation will make success much less likely.

  • Kent Goodwin

    For what it is worth, I am a glaucoma patient with persistently high IOP (mid-20’s) despite mulitple eyedrops, a total of 5 per day in each eye. I just completed a canaloplasty in one eye and my IOP has dropped to 9. The post-op has been smooth and relatively painless. If the pressure drop is sustained I will be free of eyedrops, not only a cost savings but a significant improvement in lifestyle.
    Many insurance companies have been reluctant to cover this procedure, but that appears to be changing (I would have had this done at least six months sooner but for reluctance by insurer). I wish I could have done it years ago.
    At this point I could not be more pleased and grateful to my doctor. Of course time will tell but this is very encouraging.
    I would encourage physicians to learn this procedure so that it can become more widespread, help more people earlier in their diagnosis, and become accepted by insurers. This is the essence of preventive medicine: improves health and lifestyle, inhibits further deterioration and therefore reduces medical costs for the long term.

  • Dr. Ari Weitzner

    you make a compelling case.

  • ab


    Canaloplasty is a bleb free procedure. The superficial flap is made watertight. The percolation of aqueous through Descemet’s enters the scleral lake formed by excising the deep flap and making the superficial flap water tight. Inside the lake are the ostia of Schlemm’s canal so once the lake is full, the aqueous has no where else to go but in the canal and through the normal collector system. This is just the deep sclerectomy part of the procedure which has been done for 15+ years in europe but this alone doesn’t provide enough IOP reduction so a bleb was required. With Canaloplasty, the patient not only has a descemet’s window and scleral lake, but the canal is also viscodilated 360 degrees opening up a potentially collapsed and dry canal (as well as collectors). In addition, a suture is tensioned around the canal to hold the canal open and expand the TM to allow egress of aqueous to enter Schlemm’s. With the 360 viscodilation and suture stent, the pressure gets low enough to where a bleb is no longer required. What this means is a happier patient due to not having a bleb and a happier doctor who doesnt have to see these patients post op all the time. Canaloplasty post ops are more like a cataract patient.

    Regarding you not doing many trabs and not wanting to go through the learning curve: If there is a procedure doctors don’t enjoy, it’s understandable why they don’t do many. When you get through the curve, you will enjoy doing this procedure (watching the light go 360 never gets old) and of course a simplified post op also helps with the fun factor. In addition, Since Canaloplasty has zero sight threatening complications reported in the clinical data and is bleb free, doctors tend to intervene earlier like Dr. Richardson (above). How many patients do you have going into phaco that are on multiple meds where simply taking out the lens isn’t going to be enough IOP reduction? Early intervention, combing with phaco, and doing a procedure that is fun with simplifed post op should open up the pool of patients for Canaloplasty. Do you agree?

  • ari weitzner

    agree- of course trabs stink and patients hate them.
    but dont you need a bleb for canaloplasty to work? i mean, the aqueous is percolating out- it has to go somewhere, just like in a trab, no?

  • I also hate trabs because the only thing you can seem to count on with a trab is that it’s going to be a hassle – if not immediately post-op there are significant long-term risks (that’s why I’ve not done one in 10 years). Oh, and patients hate them. How many patients thank you for dropping their pressure with a trab? Not many. Why? Because their vision is not better (may be worse) and now they have chronic ocular surface disease.

    It’s true that canaloplasty has a steep learning curve. However, once you have created a few Descemet’s windows and seen the aqueous percolate through the membrane, it becomes obvious why this just works. Oh, and patients love it. Why? Because for most of them it doesn’t negatively affect their vision or ocular surface and (this is key) you have just saved them up to $1,000 a year in glaucoma medication expenses.

    I am now offering this to almost all of my cataract patients who have open angle glaucoma (except those who are end-stage – they go on to the glaucoma specialist for a trab). Many patients upon hearing that they could potentially stop taking one of their glaucoma medications post-op are quite interested in having this done.

    That being said, this is clearly not a surgery for everyone. Compared to Descemet’s membrane, the posterior capsule seems to have the strength of Kevlar. Any surgeon who is not comfortable polishing the posterior capsule (or using 25g vitrectomy forceps to peel off a posterior capsular plaque) is probably not going to enjoy doing canaloplasty.

    David Richardson, M.D.
    Medical Director
    San Gabriel Valley Eye Associates, Inc.

    San Gabriel Office:
    207 S. Santa Anita St., Suite P-25
    San Gabriel, CA 91776
    (626) 289-7856

    Pasadena Office:
    800 E. Colorado Blvd.
    Suite 450
    Pasadena, CA 91101
    (626) 289-2223

  • ab

    Many doctors don’t do many trabs because they don’t like dealing with the bleb, the associated complications, and all that post op care. When people or doctors don’t like doing something, they look for alternatives. In this case, SLTs, and meds. Find a procedure that you enjoy doing with simple post op care and your surgical glaucoma volume will increase. Plus, since there is no bleb and no reported sight threatening complications (in the FDA data), doctors tend to intervene earlier with Canaloplasty. Some doctor make this their first line of defense against glaucoma (what’s better… a well controlled patient on meds for 20 years or a successful Canaloplasty today?). In addition, how about combining with phaco when you have a patient going into cataract surgery that’s on glaucoma drops. They will undoubtedly appreciate the lifestyle change of being (most likely) off meds as well as reducing or eliminating the financial burden of drops. During your learning curve, if things don’t go as planned, just convert to a trab, at least you gave the patient the opportunity to be bleb free!

  • Dr. Ari Weitzner

    those are reasonable points.
    since i dont do too many trabs, i dont want to go through the learning curve.

  • ab

    The published data is learning curve data. Most proficient Canaloplasty surgeons will tell you they are more in the 12-14 range once out of their learning curve. By this time, they are making larger scleral lakes, bigger windows in descemets, and making the suture tighter. Some doctors say that you don’t need super low pressures since it may narrow the diurnal curve. The benefit is clearly there for the patient to be bleb free and surgeons will enjoy post op care that resembles a cataract patient. Speak to some of the patients who have a Canaloplasty in one eye and a trab in the other and its clear which procedure the patient pref
    ers. With Canaloplasty, the surgeon can always convert to a Trab intra-op so why not provide the patient with the opportunity to be bleb free?

  • Dr. Weitzner

    no question that anything beats a bleb. but the data i have seen does not support your observation that they are getting iop’s down to 12, which is often the target iop in sick eyes. if you have data to support that, i would love to see it. the technique looks too difficult to be adopted widely. i am sure the other devices out there, like trabectome, elt, implants to create bypass to suprachoroidal space etc. will be better and easier.

  • AB

    I’ve heard that experienced Canaloplasty surgeons are getting more in the range of 12-14 and are intervening earlier due to a better safety profile and much less risk of hypotony. Combine it with phaco and I’ve heard they are getting another point or two reduction. Definitely more difficult than a trab but spending more time in the OR beats managing blebs and you know the patients would prefer not having a bleb too.