The Ex-PRESS Glaucoma Filtration Device is a small, non-valved implant that was designed to lower intraocular pressure (IOP) by shunting aqueous humor from the anterior chamber into the subconjunctival space. The implant was developed in response to the need for more straightforward, standardized and safe surgical technique than standard filtration surgery. No iridectomy and no sclerectomy is needed if an Ex-PRESS device is implanted under a partial-thickness scleral flap. This may reduce surgical time and complications when compared to a standard trabeculectomy.