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Medical Author:

Andrew A. Dahl, MD, FACS

Andrew A. Dahl, MD, FACS

Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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The two main types of glaucoma are open-angle glaucoma and angle-closure glaucoma. In angle-closure glaucoma, the normal drainage canals within the eye are physically blocked. Angle-closure glaucoma can be acute (sudden in onset) or chronic (lasting a long time), while open-angle glaucoma is usually chronic. In open-angle glaucoma, the drainage system itself is open but microscopic abnormalities within it prevent normal outflow of fluid. Both angle-closure glaucoma and open-angle glaucoma may cause optic nerve damage and vision loss with or without symptoms. Glaucoma is either primary (occurring without an underlying other cause or other eye disease) or secondary (related to other reasons, such as trauma, inflammation or medication). Subtypes of glaucoma include, among others, congenital glaucoma, childhood glaucoma, and normal (or low) tension glaucoma.

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Acute Angle-Closure Glaucoma Acute angle-closure glaucoma is caused by a rapid or sudden increase in pressure inside the eye, called intraocular pressure (IOP). The condition requires treat...learn more >>

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