What is Angle Recession Glaucoma?
Traumatic glaucoma refers to a group of ocular disorders that occur after the eye undergoes trauma. Following this trauma, different mechanisms can cause an abnormal elevation of pressure inside the eye, called intraocular pressure (IOP), and increase the risk of damage to the optic nerve. Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure typically ranges from 10 to 20 mm Hg. When eye pressure is higher than 20 mm Hg, a person may be at an increased risk for developing glaucoma. High pressure inside the eye is caused by an imbalance in the production and drainage of fluid in the eye (aqueous humor). The channels that normally drain the fluid from inside the eye do not function properly or are blocked. More fluid is continually being produced but cannot be drained because of the improperly functioning or blocked drainage channels. This results in an increased amount of fluid inside the eye, thus raising the pressure. Another way to think of high pressure inside the eye is to imagine a water balloon. The more water that is put into the balloon, the higher the pressure inside the balloon. The same situation exists with too much fluid inside the eye. The more fluid, the higher the pressure. Also, just like a water balloon can burst if too much water is put into it, the optic nerve in the eye can be damaged by too high of a pressure. Glaucoma is usually high pressure inside the eye that damages the optic nerve and can result in permanent vision loss. Not all three criteria (that is, high pressure inside the eye, optic nerve damage, and vision loss) are required to diagnose glaucoma; however, a diagnosis of glaucoma is often made when all three criteria are present.
The angle of the eye is the anatomical portion of the eye that contains the structures that allow fluid to drain out of the inside of the eye. The angle is located between the peripheral cornea and the peripheral iris. The angle contains the trabecular meshwork, which acts as a filtration system for the aqueous fluid draining from the eye. In cases of blunt trauma, the angle can be subjected to shearing forces, injuring the trabecular meshwork and impairing its function. This is called angle recession. The angle of the eye can be visualized though a procedure known as gonioscopy. The angle cannot be seen by the ophthalmologist on examination with only a flashlight or a slit lamp. Angle recession glaucoma is a form of traumatic glaucoma. It is classified as a type of traumatic secondary open-angle glaucoma. This means that the open-angle glaucoma occurs due to a specific cause, in this case a traumatic event. Angle recession, with or without a diagnosis of glaucoma, may result after the eye experiences blunt trauma. Although angle recession glaucoma is uncommon, it may not be readily diagnosed because the onset of symptoms or the discovery of the anatomical abnormality is often delayed. The eye injury might have occurred a long time ago and, perhaps, has even been forgotten by the person. Of those eyes with angle recession, only some develop glaucoma. In those that do develop glaucoma, the onset is extremely variable, ranging from immediately following the trauma to months or even many years later. The risk of eventual progression to glaucoma is generally accepted to be proportionate to the extent of the angle recession, although the presence of angle recession alone is not a good predictor for the occurrence of glaucoma. The anatomical angle is present for 360° between the peripheral cornea and the peripheral iris. Glaucoma following an angle recession that involves less than 180° of anatomical damage to the angle is very unusual. Recessions involving more than 180° of the iris are associated with a higher incidence of glaucoma. Eyes with an angle recession involving more than 240° of the iris appear to be at the highest risk for glaucoma.
In the United States, over 1 million Americans experience eye injuries each year. Blunt eye injuries are estimated to account for over 60% of all episodes of eye trauma. Although injuries often occur to only one eye, the incidence rate of trauma to both eyes is as high as 27%. In 1988, a study of adults in New England yielded an annual rate of 9.75 eye injuries per 1,000 people, based on a self-reported history. In 1990, an estimated hospitalization rate for children with eye trauma was reportedly 15.2 eye injuries per 100,000 children per year. Work-related injuries have been reported as 13% to 18% of total eye trauma cases. Injuries at home account for 27% to 31% of eye trauma cases, followed by assault (11% to 37%), recreation (approximately 25%), travel (approximately 5%), and miscellaneous (for example school, unknown <5%).