Aqueous humor is produced by the ciliary body and passes from the posterior chamber through the pupil into the anterior chamber into the trabecular meshwork, Schlemm’s canal, and finally into the episcleral venous system. The alternative path is the “uveoscleral outflow” that drains fluid through the ciliary muscle into the supraciliary and suprachoroidal spaces and then out of the eye through the sclera. Approximately 80% of aqueous humor is removed by the conventional trabecular meshwork pathway, and the remainder is removed by the uveoscleral pathway. Elevated IOP in glaucoma is caused by alterations to the conventional trabecular meshwork pathway. The figure adapted from Berwick Eye and Surgicentre ( www.berwickeye.com.au/glaucoma.htm).