Viscocanalostomy Procedures—Reply

In reply

I appreciate Dr Miller’s interest in my editorial. I was asked to write the piece specifically to put the accompanying monkey study¹ into the physiological and clinical context. I did point out that the procedure, being based on a false premise, seemed unlikely to work according the hypothesis of circumferential flow in the canal of Schlemm. The disappointment is that such studies came so late in the development of the procedure, but it is neither fair nor realistic to distract rare scientists from their crucial work with investigations of every new surgical idea.

I have long advocated the development of a surgical procedure for glaucoma that would circumvent the necessity of the odious filtration bleb. I admire and encourage anyone with new ideas in this realm. The point I failed to make clearly enough is that surgical advancements, as with any new idea, should be based on a viable hypothesis. That hypothesis should be tested in some model, preferably first in the laboratory and then in the clinic. Following encouraging pilot data, the procedure should be evaluated in a prospective clinical trial, ideally multicentered, randomized, and double masked.

We have learned a great deal about designing clinical trials in the past decade. Clinical research is perhaps the most difficult variety of medical investigation to perform, with surgical research among the most daunting. Nonetheless, we have advanced well beyond the 19th-century practice of looking over the surgeon’s shoulder to form our opinion. We require controlled, comparative, and published data. Viscocanalostomy or any new procedure must prove its worth to be studied by others. The goal is not to understand viscocanalostomy, but to design procedures that have a sound physiological basis and hold up to scientific scrutiny. Some of the spin-offs, such as deep sclerectomy, may have better potential, but these also need controlled studies.

Dr Miller criticizes the glaucoma experts for not studying the procedure, but that is exactly what Dr Tamm and his colleagues have done. Their work should not then be dismissed as irrelevant because it is in a monkey. Glaucoma experts that I know would welcome an effective, safe alternative to traditional glaucoma procedures, but they require credible data, not anecdotal data, before implementing it in their patients.

The introduction of new surgical procedures poses a substantial ethical dilemma that receives increasing social scrutiny. I encourage innovative surgeons to try to design controlled studies that are externally reviewed before introducing them into their clinics. The heavily regulated, but equally heavily criticized, process of new drug introduction could serve as one model. Thank you for the opportunity to extend the dialogue on this topic.

Correspondence: Dr Van Buskirk, Devers Eye Institute, Good Samaritan Hospital, 1040 NW 22nd Ave, Suite 200, Portland, OR 97210.