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Editorial IGR 10-4
From the Chief Editor
A breakthrough for glaucoma surgery
R.N. Weinreb, MD, La Jolla, CA
David S. Greenfield, MD, Palm Beach Gardens, FL
"There is nothing more difficult to plan, more doubtful of success, nor more dangerous to manage than the creation of a new order of things" "Whenever his enemies have the ability to attack the innovator, they do so with the passion of partisans, while the others defend him sluggishly, so that the innovator and his party alike are vulnerable." Niccolo Machiavelli, The Prince (1513)
We need a breakthrough in glaucoma surgery. Trabeculectomy, the gold standard glaucoma procedure, has been around for forty years. At the time of its introduction, this guarded procedure offered important advantages over the prevailing surgical approaches. And, since then, it has been re-invented with the use of fornix-based flaps, adjunctive anti-scarring agents, releasable sutures and laser suture lysis. Each of these developments provide incremental advantages that appear to have improved surgical outcomes and safety. But if you had glaucoma and needed surgical treatment would you really want to undergo and then live with trabeculectomy?
If you are like me, perhaps you are thinking that trabeculectomy would not be the appropriate procedure for you. It might be because the risk of bleb leak, bleb infection or endophthalmitis following trabeculectomy is unacceptably high. Or it might be due to the potential for bleb dysaesthesia that you often observe in your patients, even those who undergo a flawless procedure and uneventful post-operative period. Or it just might be that trabeculectomy is not a permanent solution, but merely temporarily lowers the intraocular pressure to delay progression, and often it or another pressure-lowering procedure will need to be performed again.
Some of you may have another procedure in mind as being preferable. Regardless of the duration of your residency within the global glaucoma community, you undoubtedly have heard colleagues opine repeatedly that one new procedure or device after the other is more effective and safer than trabeculectomy. With few exceptions, such claims are made by pundits who tout their own short-term (often less than six months) results with retrospective and non-randomized collection of data. Such reports do not provide the high level of confidence I seek before performing the new procedure in my patients, and certainly would not be an attractive surgical option for myself, if needed.
Are glaucoma tube implants the answer? Glaucoma tube implants have been shown to be at least as effective as trabeculectomy and have fewer adverse events in a randomized and prospective clinical trial of just more than two hundred patients who had previous cataract surgery and/or failed trabeculectomy. The results of a comparison of these procedures as a primary glaucoma surgical procedure are not yet available. However, the advantages of a glaucoma tube shunt, if real, seem to me to be only marginally better and this is not a procedure that I would want for myself. I suspect that even the most enthusiastic of the tube implanters would agree that better options are needed.
Many of us recognize that it is a need that drives discovery. Not only is there a need for a breakthrough in glaucoma surgery, but now I believe that the time for it has arrived. The compelling need already is triggering the research, development and commercialization of glaucoma surgical innovation. Never before have so many of our most talented colleagues addressed this critical need. And never before have they had the tools or resources to address this challenging problem as they have today. Industry hears the message, and is investing sizable resources to develop novel technologies for glaucoma surgery. Such a technology ideally will allow regulation of intraocular pressure to a desired level, sustain the lowering and allow it to be adjusted even lower if necessary, be easily performed, be safe, be well-tolerated and be affordable. It is possible that such a procedure even exists today, but it has not yet been adequately studied or it has not yet been re-invented with modifications that make it even better.
We also now have some rational and systematic guidelines for conducting investigation of new glaucoma surgical procedures and devices, The World Glaucoma Association Guidelines on Design and Reporting of Glaucoma Surgical Trials. Until now, consensus on how to do this has largely been lacking for glaucoma surgery. With major input and direction from Tarek Shaarawy, Mark Sherwood and Franz Grehn, who are to be congratulated for their outstanding work, these guidelines are a must read for anyone planning to investigate, develop or implement a new glaucoma surgical procedure. More than seventy scientists and researchers from throughout the world debated for more than two years the guideline success criteria, statistical methods, economic impact, and ethical considerations. As a result, the final product recognizes the limitations of surgical trials, and also delineates how to investigate a new surgical technology to improve efficacy and preserve vision-related quality of life. But is validation in clinical trials enough to change clinical practice?
I suspect that not many of us understand that with discovery and appropriate validation in clinical trials, one only begins a lengthy process of diffusion of this innovation so that it is widely adopted in clinical practice. Having a new idea adopted, even when it has obvious advantages, is difficult. Many believe that advantageous innovations will sell themselves, and that the obvious benefits of a new idea will be widely realized by potential adopters and that the innovation will diffuse rapidly. Most innovations, in fact, diffuse at a disappointingly slow rate, at least in the eyes of the inventors who create the innovations and promote them to others. Many innovations require a lengthy period for the time when they become available to the time when they are widely adopted.
With all that is happening to discover and develop a more effective, safer and
better tolerated glaucoma surgical procedure, nevertheless, it is probable in my
opinion that a breakthrough is looming on the horizon that will disseminate quickly
and broadly.
