Reply

Abstract

Drs. Walland and Thomas are major contributors in the area of cataract surgery and glaucoma. We greatly respect their work and quoted liberally from their papers in our recent review. In the title of their letter, Drs. Walland and Thomas describe using cataract surgery for OAG by modifying Oscar Wilde’s ironic quotation, “Second marriage is the triumph of hope over experience.” They in effect compare cataract surgery for reducing IOP to the chances for success in a second marriage. Immediately we can see that this debate has become quite emotional. In fact, the authors feel so strongly about this controversy that they titled a 2012 review with their conclusion, “There is insufficient evidence to recommend lens extraction as a treatment for primary open angle glaucoma.”1 Most of their comments are criticisms of data and conclusions from papers that we reference—not about our review per se. They are careful analysts and make some valid arguments. Although we could rebut many of their points, we agree with their conclusion that the evidence for cataract surgery lowering the pressure in OAG is imperfect. In fact, we say this many times in our review. But most evidence for what we do in clinical practice is imperfect and rarely is what we do based on large randomized clinical trials (RCTs). We find it curious that Drs. Walland and Thomas seem to assume that cataract surgery in angle closure has been proven to be effective whereas in OAG it can only be proven with a future RCT. Although there have been some small RCTs in patients with acute primary angle-closure glaucoma (ACG) and advanced chronic angle closure, we are not aware of any RCT showing that cataract surgery lowers IOP in less severe ACG. Despite the absence of supporting RCTs, we have frequently used cataract surgery to help patients with moderate angle closure and even in patients with clear lenses.2,3 The major insight of the Poley et al. papers4,5 is not that cataract surgery in OAG lowers IOP. That was known but not thought to be clinically significant. Their discovery was that the pressure reduction is proportional to the preoperative pressure and at higher levels may be very significant. The impressive consistency of this finding—and the consistent proportionality—increases the credibility of these studies despite the absence of a confirming RCT. Cataract surgery as a treatment for glaucoma—as well as the emergence of microinvasive glaucoma surgery (MIGS)—is changing the way we look at glaucoma surgery. In the past, glaucoma surgery has been limited to the small number of patients (fewer than 5%) with advanced disease and progressive damage despite maximal medical treatment. These patients need trabeculectomies and tubes—not cataract surgery. These high-risk procedures have been the province of glaucoma specialists. But the finding that cataract surgery can lower IOP—along with the opportunity to add a MIGS procedure—has opened up the possibility of applying a very safe surgical treatment to the other 95% of glaucoma patients who are controlled or nearly controlled on medical therapy. The goal is to reduce the IOP to a safer level and perhaps eliminate an eyedrop or two. We think this is a very worthy objective but many glaucoma specialists (such as Drs. Walland and Thomas) are not impressed. The ironic Oscar Wilde might say that their main objection to viewing cataract extraction as a glaucoma surgery is a lack of suffering—for both the patient and the surgeon. Drs. Walland and Thomas describe their comments as “deeply unfashionable.” They see themselves speaking out against a “potentially massive change in clinical practice”—a tidal wave of cataract surgery performed for pressure indications only. But in a letter that stresses the need for evidence, we wonder what their evidence is for this volume of unnecessary cataract surgery. In the highly competitive world of cataract surgery, we doubt that practices can be built on doing unhelpful surgery. This debate began the moment that Dr. Poley first presented his findings at the 2007 American Society of Cataract and Refractive Surgery meeting.4 The intensity has surprised us because the general response to these findings has just been to consider cataract surgery a little sooner in patients with glaucoma. This does not seem very controversial, and we wonder why Drs. Walland and Thomas are so passionately negative about a glass that is at least half full.