Glaucoma - Causes

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Causes of Closed-Angle Glaucoma

People with acute closed-angle glaucoma often have a structural defect that causes a narrow angle between the iris and cornea where the aqueous humor circulates. Conditions that suddenly dilate the pupils may cause this shallow angle to close and precipitate attacks of acute glaucoma in susceptible people. Such conditions may include:

• Certain drugs such as antihistamines, tricyclic antidepressants, some asthma medications (nebulized ipratropium), some anti-seizure drugs (topiramate)
• Darkness
• Emotional stress

Causes of Secondary Glaucoma

When intraocular pressure leading to glaucoma is caused by other diseases or conditions, it is known as secondary glaucoma. Secondary glaucoma may be chronic or acute, mild or severe.

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Medical Conditions. A number of diseases can contribute to the development of intraocular pressure leading to glaucoma:

• Diseases that affect blood flow to the optic nerve (diabetes, high blood pressure, migraine; people with type 2 diabetes should be regularly screened for glaucoma.)
• Hypothyroidism
• Sleep apnea
• Physical injury in the eye
• Extreme nearsightedness (myopia)
• Previous eye surgery
• Other disorders, including leukemia, sickle cell anemia, and some forms of arthritis

Corticosteroids. Corticosteroids, commonly called steroids, have multiple effects on the trabecular meshwork and may even cause genetic changes. In fact, studying the effects of steroids on the eye is helping researchers understand the glaucoma disease process. Steroids pose a higher or lower risk depending on the form:

• Taking topical steroid treatments in the eye poses the highest risk. It must be monitored carefully since, in some cases, damage may be permanent.
• Taking oral corticosteroids, particularly in high doses or for long periods, increases the chance of glaucoma. In such cases, the eye disorder typically develops almost immediately and reverses within 2 weeks after the drug has been withdrawn.
• Inhaled steroids were not thought to cause glaucoma, but there is some risk in people with a family history of glaucoma and other risk factors.

Review Date: 03/03/2007
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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