Ex-PRESS Glaucoma Filtration Device: Theory, Technique and Results

The Ex-PRESS glaucoma filtration device (Alcon Laboratories, Fort Worth, TX , USA) is designed to drain aqueous fluid from the anterior chamber to the subconjunctival space and form a filtration bleb, akin to a trabeculectomy. In this article we will review the surgical indications, preoperative evaluation, surgical techniques and postoperative considerations of this ophthalmic device. J Emmetropia. 2013; 4: 105-114 Description of Device The Ex-PRESS glaucoma filtration device (Alcon Laboratories, Fort Worth, TX, USA) is designed to drain aqueous fluid from the anterior chamber to the subconjunctival space and form a filtration bleb, akin to a trabeculectomy1. The Ex-PRESS glaucoma device is currently available in two models: an R-model and a P-model. The Ex PRESS R-model has a beveled tip, an external diameter of 400 microns (27-gauge), an internal lumen of 50 microns, a total device length of 2.96 mm and a uniform back plate. The Ex-PRESS P-model has a decreased bevel angle, an external diameter of 400 microns, a total device length of 2.64 mm and a vertical channel back plate. It is available in both a 50-micron and 200-micron internal lumen size (Figure 1)1. The Ex-PRESS glaucoma device is composed of biocompatible stainless steel with a spur to prevent extrusion of the device and a flat external backplate to prevent intrusion2. The backplate and spur are designed to conform to angle anatomy, and the distance between them approximates that of the scleral tract made by the device3. The P-model features vertical channels in the plate, designed to enhance posterior flow of aqueous and formation of a more diffuse posterior bleb. The devices also contain a relief port designed to provide an alternative pathway for aqueous should the axial lumen become occluded by iris, fibrin or blood1. Surgical indications The Ex-PRESS glaucoma device is indicated for use in open angle glaucoma. It is the authors’ experience that the device is effective in both wide open and narrow angles, as long as there is no peripheral anterior synechia in the area of intended implantation. The Ex-PRESS may be considered in patients who are candidates for a traditional trabeculectomy. Implantation of the ExPRESS shunt may be combined with lensectomy and intraocular lens (IOL) implantation. UPDATE/REVIEW 1University of Utah, Salt Lake City, Utah, USA 2University of Toronto, Toronto, Ontario, Canada Disclaimer: This article was previously published as Chapter 44 of the book Catarata y Glaucoma (ISBN: 9788493989804), coordinated by Dr Ramon Lorente. This book belongs to the series of annual monographs of the Spanish Society of Refractive Implant Ocular Surgery (SECOIR) and is reproduced with the consent of the copyright holders. Corresponding Author: Ike K. Ahmed, MD Credit Valley Eye Care, 3200 Erin Mills Parkway, Unit 1, Mississauga, Ontario, L5L 1W8, Canada. E-mail: [email protected] Figure 1. The Ex-PRESS R-model and P-model, with the dimensions and specifications of each.