Trabeculectomy: methods to improve safety, optimise outcomes, and assess filtering blebs

Deposited with permission of the author. © 2010 Dr. Anthony Philip (Tony) WellsTrabeculectomy is the most commonly performed incisional glaucoma procedure worldwide. This thesis incorporates a compilation of papers with the aims of improving the surgical approach to trabeculectomy, and via improved assessment of results of surgery, optimising outcomes. In the first weeks after surgery, success of trabeculectomy hinges on the absence of complications, with the more important complications resulting from loss of control of intraocular pressure. The interactions between aqueous flow, scleral flap construction, and the placement and tension of sutures in the scleral flap can effectively control IOP, and are under the control of the surgeon. The surgical approach, independent of antimetabolite use, also affects bleb morphology. Via papers that are included in this thesis, I describe how I and coworkers have tested, modeled, and validated a ‘Safe Surgery System’ for trabeculectomy, an approach initiated by Professor Peng Khaw at Moorfields Eye Hospital, with excellent results and external validation and recognition. Later in the postoperative course, once the sclera in the trabeculectomy site has started to heal and remodel, the scleral component effectively becomes a fistula*; the functional component and the important determinant of long term success is the filtering bleb. In addition to descriptions of some minor complications of filtering blebs that had not previously been described, this thesis contains the story of the development and testing of a bleb grading system that became the Moorfields Bleb Grading System (MBGS). Although the current MBGS has flaws as described in the included publications, I believe it is still the best available tool for bleb grading since it captures important information that others ignore. My interest in the surgical and post-surgical management of blebs has led to related projects including textbook chapters regarding bleb assessment and management, and also to investigate the possibility of in-vivo imaging of blebs at tissue and cellular levels. Two papers at the end of this thesis show the potential for fluorescence-mode confocal microscopy to be applied to bleb and other wound healing research, perhaps with practical applications once suitable methods for selective fluorescent labelling become available