Ocular examination of the front portion (anterior chamber) of the eye. Gonioscopy is used primarily for viewing the angle between the iris (the colored part of the eye) and the cornea (the clear outer covering on the exposed part of the eye). This examination is important in diagnosing and managing glaucoma, a disease in which the pressure inside the front chamber of the eye often rises and damages the optic nerve. Since the angle cannot be observed directly, the gonioscope uses a modified contact lens with mirrors and a special lamp to allow the eye specialist to look inside the anterior chamber, examine its structures, and measure the angle. Before the procedure, the eye is numbed with anesthetic drops, and a cushioning agent (in drop form) is added to position the lens correctly over the cornea and maintain comfort. After the procedure, the eye is rinsed and the cornea inspected. Gonioscopy is performed as part of the initial diagnosis of glaucoma and at regular intervals afterward to gauge the progression of the disease and assess the effectiveness of treatment.