Aqueous is produced by the ciliary body, enters the posterior chamber between the iris and the lens and passes through the pupil into the anterior chamber then to the trabecular meshwork to the anterior chamber angle. The major resistance to aqueous outflow from the anterior chamber occurs at the trabecular meshwork and Schlem s canal. It varies during the day with the highest readings in the early morning. Thus a single normal reading does not rule our glaucoma. Normal is up to 0.4 As cupping develops, the disc vessels are displaced nasally.
Asymmetric cupping suggests glaucoma.
An important step the assessment of glaucoma is to visualize the angle structures. Structures seen on gonioscopy of a normal angle include Schwalbe s line, scleral spur and trabecular meshwork. The angle is graded according to the number of structures identified on gonioscopy. Creates an opening between the anterior and posterior chambers to relieve the pressure between the two compartments. Argon laser application to the trabecular meshwork facilitates outflow of aqueous and enhances the function of the meshwork.