Histopathologic features of trabeculectomy surgery

Purpose: Trabeculectomy surgery is the most common operative procedure for the treatment of medically uncontrolled glaucoma. Variability exists in both the design and the position of the limbal wound as well as in outcomes, even in cases with similarly designed wounds. The purpose of this study is to describe the histologic features of the surgical site of human eyes received at a pathology laboratory that had undergone trabeculectomy surgery and then attempt to explore possible associations of these features with success or failure of surgery. Methods: We examined 64 autopsy and enucleated eyes of 53 patients obtained at the Eye Pathology Laboratory, Wilmer Eye Institute, Baltimore, Md, between January 16, 1974, and November 15, 1999. Examined aspects included the position, dimensions, and depths of the trabeculectomy site; features at the internal opening; and the inclusion of trabecular meshwork in the internal resection. An attempt was also made to judge the success of the trabeculectomy by a comparison of preoperative and postoperative intraocular pressures. Results: Of all the histopathologic features examined, there was a statistical difference between the success and failure groups in only the presence of a cleft and the location of the posterior incision. Conclusions: The main finding of this study is that there is a large degree of variability in the size, position, and pathologic features of trabeculectomy sites. Features that can be avoided with the initial surgical approach, particularly a posterior resection posterior to the scleral spur, may increase the chance of surgical failure.