What is glaucoma?
Glaucoma is a group of diseases that results in damage to the nerves that carry the single to the brain. These diseases are often associated with pressures inside the eye that are above average. However, the increased pressure is not neccessarily the source of the damage in all patients. Other factors include genetic predisposition and conditions that may result in poor blood to the nerves such as diabetes and low blood pressure at night time. The type of glaucoma influences the overall prognosis and dictates what glaucoma treatments are required to minimize further damage from the disease.
Tests to diagnose and monitor glaucoma
Tonometry – Several methods are used to measure the intraocular pressure in the eye (IOP). Intraocular pressure is important to gauge glaucoma risk as well as to help monitor response to therapy. IOP is measured every visit.
Pachymetry – The corneal thickness (CCT) is measured on all glaucoma suspects and glaucoma patients. Patients with thinner corneas are at higher risk of developing glaucoma and having progressive forms of the disease. Patients with thick corneas may have artificially elevated intraocular pressure measurements. Pachymetry is typically required only once.
Gonioscopy – A special lens is used to examine the anatomic angle to designate it as either open or narrow. Other abnormalities of the angle can also be diagnosed such as neovascularization (abnormal blood vessels) or traumatic damage (angle recession). How often gonioscopy is performed depends on the type of glaucoma as the angle status may change with time.
Optic Nerve Imaging – The nerve fiber layer of the eye can be measured using various machines. The measurements look for thinning patterns consistent with glaucoma. They allow for monitoring of the nerve layer thickeness over time.
Visual Field – The visual field tests a patient’s peripheral vision and help capture if functional damage has occurred. For patients on treatment, changes may take years to become visible. Testing may be performed every 6-12 months or more frequently if patients have changes in vision or if they are not stable on their current treatment.