There is a number of variations for this surgical procedure, but essentially, all filtering operations share the same basic mechanism of action and general surgical principles. Trabeculectomy is currently the most frequently performed surgical procedure for glaucoma. Trabeculectomy is a safe and effective procedure in that it has a high success rate. In this surgery, the surgeon aims to allow aqueous humor to bypass the trabecular meshwork into the subconjunctival space. This would ensure an optimum intraocular pressure (IOP) while maintaining the anatomy of the globe that is indicated by prevention of shallowing of the anterior chamber (Pederson, 1996, chap 18).
Intraocular pressure (IOP) is determined by the balance between aqueous humor production and outflow. There are diurnal variations in aqueous humor production, but it has been observed that alterations in IOP usually result from a variation in the resistance to aqueous outflow. For normal clinical purposes, IOP can be defined, thus, as pressure which does not lead to glaucomatous damage of the optic nerve head. Aqueous outflow occurs through both conventional and unconventional routes. In the former, aqueous moves through the trabecular meshwork and into Schlemm's canal, and from there to episcleral veins via collector channels that traverse the limbal sclera (Seah et al., 1995, 73-79).
Conventional aqueous humor outflow begins with the trabecular meshwork. ...Show more