The diagnosis of glaucoma is based on history, clinical signs, tonometry and gonioscopy. People with glaucoma often report a constant headache that medication will not help. In later stages of glaucoma, the eye becomes enlarged. Tonometry is the measurement of pressure within the eye. A variety of techniques can be used to estimate intraocular pressure, including Schiotz tonometry and Applanation tonometry.
Most veterinary ophthalmologists use the highly accurate applanation tonometer.
Gonioscopy is a technique used to evaluate the drainage angle. This lens allows us to directly visualize the drainage angle. Gonioscopy occasionally requires sedation but in most pets it can be performed with the use of topical anesthetics only. The technique is essential to evaluate the non-glaucomatous eye for risk of a future attack of glaucoma. Our pets are not like this.