Abnormal eye pressure can be a symptom of a build-up of aqueous humor in the eye, inadequate or slow drainage of aqueous humor, injury to the eye, or medications, states All About Vision. These symptoms can result in glaucoma. High blood pressure can also lead to elevated pressure in the eye, as can less common conditions such as corneal arcus, pseudoexfoliation syndrome or pigment dispersion syndrome.
A patient is considered to have high ocular pressure if it is 21 millimeters of mercury or higher, says All About Vision.
Hypotony is abnormally low eye pressure, explains the Glaucoma Research Foundation. It is often caused by a leakage of fluid after eye surgery, chronic eye inflammation, or a detached retina or choroid. The choroid is the layer of the eye between the white of the eye and the retina. The inner front area of the eye, also known as the anterior chamber, can also be too shallow. Hypotony is considered problematic if the eye pressure drops below 5 millimeters of mercury.
Glaucoma is a leading cause of blindness, and open angle glaucoma is insidious, as its symptoms are silent or vague, says Mayo Clinic. On the other hand, closed angle glaucoma is considered a medical emergency. The symptoms are an excruciating headache, pain and redness in the eye, halos around lights, blurred vision, nausea and vomiting.