| Subject | Contents |
| Definition | A condition of increased fluid pressure inside the eye ( intraocular pressure ). This increased pressure damages the optic nerve causing partial vision loss , with blindness as a possible, eventual outcome. |
| Alternative Names | Secondary glaucoma; Open angle glaucoma; Chronic glaucoma; Closed angle glaucoma; Congenital glaucoma; Acute glaucoma |
| Causes, incidence, and risk factors | Glaucoma is the third most common cause of blindness in the United States. There are four major types of glaucoma: Open angle or chronic glaucoma Closed angle or acute glaucoma Congenital glaucoma Secondary glaucoma All four types are characterized by increased pressure within the eyeball, and therefore all of them can cause progressive damage to the optic nerve. Increased pressure occurs when the fluid within the eye (called aqueous humor), which is produced continuously, does not drain properly. The pressure pushes on the junction of the optic nerve and the retina at the back of the eye. This reduces the blood supply to the optic nerve, which carries vision from the eye to the brain. This loss of blood supply causes the individual nerve cells to progressively die. As the optic nerve deteriorates, blind spots develop in the field of vision. Peripheral vision (side vision) is affected first followed by front or central vision. Without treatment, glaucoma can eventually cause blindness. Acute glaucoma may occur in persons who were born with a narrow angle between the iris and the cornea (the anterior chamber angle). This is more common in farsighted eyes. The iris may slip forward and suddenly close off the exit of aqueous humor, and a sudden increase in pressure within the eye follows. Symptoms of pain, redness, nausea, and visual loss develop rapidly. Angle closure may be provoked by the use of drops that dilate the eyes in susceptible persons. Attacks may also develop without any obvious triggering event. This is more common in the evening because the eye's pupils naturally dilate in dim light. Chronic open angle glaucoma is by far the most common type of glaucoma. In open angle glaucoma, the iris does not block the drainage angle as it does in acute glaucoma. The fine fluid outlet channels within the wall of the eye gradually narrow with time. The disease usually affects both eyes, and over a period of years the consistently elevated pressure slowly damages the optic nerve. Chronic glaucoma has no early warning signs, and the associated loss of peripheral vision occurs so gradually that it may go unnoticed until a substantial amount of damage and vision loss have occurred. The only way to diagnose glaucoma early is through routine eye examinations. Secondary glaucoma is caused by other diseases including some eye diseases ( uveitis ) and systemic diseases, and by some drugs (corticosteroids). Congenital glaucoma, present at birth, is the result of defective development of the fluid outflow channels of the eye. Surgery is required for correction. Congenital glaucoma is often hereditary. Risk factors depend on the type of glaucoma. For chronic glaucoma, the risk factors include; age over 40, a family history of glaucoma, diabetes , and nearsightedness . People with a family history of open angle glaucoma have twice the risk of developing open angle glaucoma as those who do not. African-Americans have four times the risk of developing open angle glaucoma as compared to Americans of European decent. It is estimated that 1 to 2% of people over 40 have chronic glaucoma with about 25% of cases undetected. The risk factors for acute glaucoma are: family history of acute glaucoma, older age, farsightedness , and the use of systemic anticholinergic medications (such as atropine or eye dilation drops) in a high-risk individual. Acute , congenital, and secondary glaucoma are much less common than chronic glaucoma. |
| Symptoms | ACUTE :Severe eye pain , facial painLoss of vision Cloudy vision with halos appearing around lights Red eye Fixed, non-reactive pupil Nausea and vomitingCHRONIC : Gradual loss of peripheral vision Most people have no symptoms until peripheral visual loss is severe Blurred or foggy vision Mild, chronic headaches Seeing rainbow-colored halos around lights CONGENITAL: Tearing Sensitivity to lightRedness of the eye Corneal haziness An enlarged cornea |
| Signs and tests | A physical examination may be non-diagnostic. Intraocular pressure fluctuates, and a single measure may catch it at a low point. Examination of the junction of the optic nerve and the retina with an instrument called an ophthalmoscope is necessary. A standard ophthalmic examination may include: Retinal examination Intraocular pressure measurement by tonometryVisual field measurement Visual acuity Refraction Pupillary reflex response Slit lamp examination |
| Treatment | The objective of treatment is to reduce the intraocular pressure . Depending on the type of glaucoma, this is achieved by medications or by surgery.
MEDICATIONS:
Acute glaucoma is a medical emergency requiring immediate treatment by an emergency center or ophthalmologist. Intraocular pressure can usually be lowered by medications that may be given orally, intravenously, or topically (as eye drops). Beta-adrenergic blocking agents in the form of eye drops are effective for treatment of open angle glaucoma. Timolol, Betagan, and OptiPranolol are examples of some of the drops available. Epinephrine drops are sometimes used in combination with other medications. In 1996, a drug called Xalatan (latanoprost) was approved by the U.S. Food and Drug Administration for the treatment of glaucoma. This medication helps to drain the aqueous outflow from the eye and lower the intraocular pressure. There are also oral medications that may be given such as Daranide, Diamox, and Neptazane. Oral medication or topical drops may be prescribed separately, or a combination of both may be used.
SURGERY:
An emergency operation, called an iridotomy, may be required for the treatment of acute glaucoma. This creates a drainage hole in the iris to relieve the pressure build up. This technique can be performed by laser surgery without making an incision in the eye.
Iridotomy or may be performed electively after an acute episode has resolved (to prevent recurrence) or in persons at high risk for angle closure before an attack. Laser treatment of the fluid drainage area in the eye may be used to treat open angle glaucoma. In severe cases that are not responsive to medical treatment, surgery can be done to create new outflow channels.
Congenital glaucoma is treated surgically since medical therapy is usually not very effective. |
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| Expectations (prognosis) | Untreated acute glaucoma results in severe and permanent vision loss after the onset of symptoms. Vision can be preserved with prompt treatment. Untreated chronic glaucoma can progress to blindness within 20 to 25 years. Early diagnosis and treatment have excellent success with preserving vision. Treatment prevents further loss, but does not bring back vision already lost. The outcome for congenital glaucoma varies depending on the age when symptoms begin. |
| Complications | Reduced vision Blindness |
| Calling your health care provider | Call your health care provider if you have severe eye pain or a sudden loss of vision , especially loss of lateral (away from the middle) vision. Call for an appointment with your health care provider if risk factors for glaucoma are present and routine glaucoma screening has not been performed. |
| Prevention | There is no prevention for the development of open angle glaucoma. If detected early, further vision loss and blindness may be prevented with treatment. Patients with risk factors for closed angle glaucoma should be evaluated and those at high risk should have laser iridotomy, which will prevent acute attacks. Careful use of dilating eye drops and systemic anticholinergic medications will minimize the risk of acute attacks in high-risk individuals. Anyone over 35 years of age should have tonometry (a check of intraocular pressure ) and ophthalmoscopy examinations every 2 years. More frequent examination is indicated when a family history of glaucoma is present or in African Americans. |
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