Glaucoma is a disease characterized by high pressure in the eye and damage to the optic nerve. Acute closed angle glaucoma is one subtype of this disease which occurs suddenly, over a period of minutes to hours. The eye becomes red and very painful, sometimes so much so that people may begin vomiting. Left untreated, the condition can progress to blindness.
Causes of Closed Angle Glaucoma
In a normal eye, clear liquid called aqueous fluid flows from the back of the eyeball, through the pupil and into the front of the eyeball. The aqueous fluid is then absorbed at the angle where the iris joins the cornea. In closed angle glaucoma, the iris is pushed forward, blocking this angle so that the aqueous fluid can no longer exit the eye. Pressure builds up inside the eye, causing pain and damage to the retina. Lens problems, bleeding and abnormal eye anatomy can all cause the iris to block the angle, preventing aqueous fluid from draining out of the eye.
Medications
Acute closed angle glaucoma can be treated with several types of medicines, according to "Rosen's Texbook of Emergency Medicine." Beta-blocker eyedrops, such timolol, help lower the pressure in the eye. Likewise, alpha-agonist eyedrops, such as apraclonidine, can lower the eye pressure. Eyedrops that make the pupil constrict, such as pilocarpine, can draw the iris away from the angle. This unblocks the channel so that aqueous fluid can once again drain out of the eye. Oral medications such as acetazolamide and injectable medications such as mannitol can also help reduce the pressure in the eye.
Side Effects of Medications
Each of these medicines, though safe, has side effects. Beta-blockers can worsen lung disease in people with chronic obstructive pulmonary disease, also called COPD or emphysema. Alpha agonists can cause a dry mouth. Pilocarpine may cause high blood pressure or a fast heart rate. Acetazolamide and mannitol can both cause dehydration and low blood pressure, leading to dizziness and fainting.
Surgery
In addition to medications, surgery is often used to definitively treat angle closure glaucoma. M. Yanoff and J.S. Duker's textbook "Ophthalmology" recommends laser iridotomy, a type of surgery in which a laser is used to burn a hole into the iris, thereby allowing fluid to drain. Goniosynechialysis is another type of surgery for closed angle glaucoma in which scar tissue that sometimes blocks the flow of aqueous humor is cut out. In addition, during this surgery the lens is often removed from the back of the eye and replaced with an artificial lens in order to decrease pressure on the back of the iris.
Prognosis
Long-term prognosis of acute closed angle glaucoma is good, if the appropriate treatment was given during the initial attack. Some people might experience an attack in the other eye and could receive a laser iridotomy in that eye prior in order to prevent an attack. Patients who are at risk for future attacks of angle closure should avoid certain medications such as decongestants.
References
- Ophthalmology; M. Yanoff and J.S. Duker, 3rd Edition; 2008
- "Rosen's Emergency Medicine, 7th Edition; J.A. Marx; 2009
