2020 Huntington Dr, San Marino, CA 91108

QUESTION:

I am submitting the question below hoping some one will be able to answer it. One of my friend just returned from his monthly visit with his ophthalmologist who advised him to consider canaloplasty surgery.

The ophthalmologist told my friend that he can not see any blockage around Schlemm’s canal but something else in the eyes( that is not visible under examination) could be blocked. The ophthalmologist recommended canaloplasty as the option. My friend was also told if Canaloplasty surgery failed to bring his IOP down, then he can consider Trabeculectomy.

I was under the impression that canaloplasty surgery is performed to clear any blockage around the eye and wonder how my friend is going to benefit from this surgery if his Schlemm’s canal is not blocked.

My friend optic nerve cup on both eyes are 0.9 and IOP on both eyes are 18. He wears glasses only to read and drive without glasses and took his DMV driver’s license without glasses.

I will very much appreciate your input pertaining to this matter.

Thanks in advance for your responses.
R*****
——————————

R*****,

I think you’re right, that it is difficult to predict how effective canaloplasty will be because there is no way to know how blocked Schlemm’s canal actually is. But, as part of the procedure, they pull a suture through the canal and tie it, which would put some tension on the canal to keep it open and probably that suture also tugs on the tm and opens it up a little (since the tm is laying on the canal).

I will be interested to hear from doctors, because I had a similar question about what order to do these operations in. As I understand it, if you really want to lower the pressure a lot (single digits), the trab (perhaps with the EX-Press shunt) is the way to go, but if you do that, a canaloplasty operation later is of no use. Whereas, by doing the canaloplasty first, you can still do a trabe later, usually (some say there can be problems from scaring during the earlier canaloplasty).

Here is an article from 2010 that explains the thinking of the different options.

http://www.reviewofophthalmology.com/content/d/cover_focus/i/1203/c/22695/

Best wishes,
B*****


ANSWER:

Dear R***** and B*****

Unlike trabeculectomy and “tubes” (e.g. Ahmed, Baerveldt, Molteno, Krupin) which are “bypass” surgeries, Canaloplasty and other “non-penetrating” surgeries work by reopening that portion of the eye’s anatomy that is most commonly blocked in open angle glaucoma: the trabecular meshwork and Schelmm’s canal. Because Canaloplasty uses the eye’s natural system there is no need to use antimetabolites such as Mitomycin-C (MMC) or 5-FU – both of which can lead to long-term risks and undesirable side effects.

The history of non-penetrating surgeries leading to Canaloplasty is fascinating and frustrating all at once. Surgeons who have not bothered to learn their history will tell you that non-penetrating surgeries are a recent “fad” and that trabeculectomy has wonderful long-term results. Do you know how trabeculectomy came about? It was actually a failed attempt to reopen the Canal of Schlemm. The entire point of the envisioned surgery was to re-establish flow through the natural drainage canal WITHOUT the creation of a BLEB! As far back as 1968 surgeons knew that blebs were undesirable. How ironic that a failed attempt to create a non-penetrating surgery was to become the most commonly performed glaucoma surgery through the latter half of the 20th century. A more detailed description of the history of Canaloplasty can be found here:

How Long Has Canaloplasty Been Around?

Unfortunately, Canaloplasty has not achieved a large following among glaucoma surgeons. Why? Well, that depends upon who you ask. If you ask a surgeon who does not perform Canaloplasty s/he will likely tell you it’s because “It doesn’t work”. That’s funny (no, it’s frankly tragic) as it does work, has peer-reviewed data supporting it and it clearly a safer surgery than either trabeculectomy or tubes. Ask most surgeons who do perform Canaloplasty and they will often tell you that they rarely perform trabs anymore and both they and their patients are much happier for it.

Why the difference of opinion? Well, I’m sorry to report that after spending many, many hours trying to teach other surgeons how to perform Canaloplasty I can state with confidence that it’s because not all surgeons are capable of performing this surgery. This is not just my opinion. If you perform a literature search on Canaloplasty you will see many articles and papers are quite frank in stating that this procedure has a very steep learning curve. It is in my opinion (as well as others) one of the most difficult of all eye surgeries to perform. It also takes a very long time relative to trabs and tubes. Despite this, it is one of the safest for patients.

So if you were a surgeon with little time (due to an overwhelming patient schedule) and perhaps average surgical skill and your patients asked you why you didn’t perform Canaloplasty are you going to tell the patient that it’s “too difficult and takes too much time for me” or are you going to say something along the lines of “It doesn’t work”? Egos are funny things, no?

As for the other oft quoted reason why Canaloplasty is not offered, “It ruins your chances of having a trabeculectomy” that’s another unsupported assumption made by surgeons who do not perform Canaloplasty. In fact, this issue was addressed in the following study:

Bottom line: if your friend’s surgeon recommended Canaloplasty he can be sure of two things: (1) his surgeon is considering his needs as a person, not just an IOP that needs to be in the single digits, and (2) that he is being cared for by a truly skilled surgeon. Does that mean that surgeons who do not perform Canloplasty are not also skilled surgeons? No, but if the reason given for not performing Canaloplasty is “It doesn’t work,” then I’d recommend getting a second opinion before going under the knife.

Warm regards,
David Richardson, MD
Patient-Focused Ophthalmologist

San Marino Eye
2020 Huntington Drive
San Marino, CA 91108
626.289.7856

Patient-Focused Websites:
New-Glaucoma-Treatments.com
About-Eyes.com

Date: Sun, Feb 8, 2015 at 12:03 PM

 

Posted in: Canaloplasty Safety and Efficacy, Canaloplasty Surgeons