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Editors Selection IGR 9-1

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Comment by Richard Lewis on:

24877 Three-year follow-up of the tube versus trabeculectomy study, Gedde SJ; Schiffman JC; Feuer WJ et al., American Journal of Ophthalmology, 2009; 148: 670-684

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The role of glaucoma drainage devices (GDDs) in the surgical management of nonrefractory glaucoma is an issue that is yet unresolved. Improved designs of GDDs has resulted in a shift in the surgical landscape with increasing preference for GDDs over trabeculectomies augmented with Mitomycin C (MMC) or 5 Fluorouracil (5FU). The tube versus trabeculectomy study is a multi-centered randomized clinical trial, designed with the primary goal of providing information for ophthalmologists on the safety and efficacy of tube surgery and trabeculectomy in eyes with previous cataract and or glaucoma surgery.

Gedde et al. demonstrate that at three years there is no significant difference between the 350-mm² Baerveldt implant and MMC-augmented trabeculectomy in the study group in terms of intraocular pressure control, visual acuity and reported complications. As glaucomacologists, we would embrace the surgical technique that would provide our patients with prolonged visual field stability with acceptable risks. However, no firm conclusions could be made as to which procedure is the superior of the two for this cohort of patients, which leaves the reader none the wiser.

As expected, there was greater early IOP fluctuation in the trabeculectomy group compared to GDD. However, I was surprised that the study did not provide any information on early post-operative management specific to trabeculectomiese.g., bleb massage, suturelysis, bleb needling with or without subconjunctival injection of 5FU. This is an important component to trabeculectomy outcome and it would certainly contribute to the IOP fluctuations as well as a cause to hypotony and the other reported early post-operative complications.

The debate on tube versus trabeculectomy will remain for as long as we have an imperfect operation

Finally, only the 350-mm² Baerveldt was used in the study and in my center the Ahmed valve (FP7) is the preferred GDD, therefore the results from the study are not useful in terms of facilitating decision making with another GDD. Thus, the relevance of this study would only apply to those surgeons whose regularly use the Baerveldt.

The study is an interesting one, but has generated more questions than solid answers. Both procedures have their risks and the outcome from each procedure would seem to depend on surgeon skill and patient selection, as highlighted by the authors. The debate on tube versus trabeculectomy will remain for as long as we have an imperfect operation.

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