There are a number of glaucoma types and the most common is known as Primary Open Angle Glaucoma. It develops very slowly and years may pass before you notice any of its symptoms. Closed Angle (aka Narrow Angle) Glaucoma can develop suddenly and when it does, it constitutes a medical emergency. There is no cure for any type of glaucoma but it can be treated and managed successfully especially when diagnosed early.
Relevant Eye Anatomy A fluid inside the eye called aqueous is continuously being made by the eye and circulates through the anterior chamber and then drains from the eye. This process creates pressure inside the eye called intraocular pressure. In a healthy eye, fluid in the front part of the eye (called aqueous humor) is continually drained out and renewed. In an eye with glaucoma, the outflow is restricted, the IOP rises and damage to the nerve fiber layer occurs. The nerve fibers are responsible for carrying visual nerve impulses through the optic nerve to the brain. Damage to these nerve fibers causes blind areas in the field of vision.
Glaucoma is a condition that damages vision in different ways depending on the type of glaucoma you have. For more on eye anatomy and eye conditions, please see the Patient Education pages.
Open Angle Glaucoma In an eye with open angle glaucoma the drainage canals are partially blocked so that fluid builds up inside the eye and the IOP increases. The blockage is not at the canal openings but further inside them. Diagnosis of open angle glaucoma is based on damage to the optic nerve where it exits the eye. When any of these fibers is damaged it cannot carry its vision data to the brain and some vision is lost permanently.
Peripheral vision is lost first but will continue to progress, if left untreated. A visual field test can determine exactly how much peripheral vision is lost and regular testing is important for glaucoma management. Another test done for glaucoma is tonometry which is how the doctor measures the IOP. Tonometry is used to monitor the IOP closely along with the appearance of the optic nerve which determines the treatment choices available. Open angle glaucoma can be treated with drops or laser surgery. If glaucoma remains unstable surgical intervention may be necessary.
Closed Angle Glaucoma Closed Angle Glaucoma is also called Narrow Angle Glaucoma and Acute Glaucoma. It is rare. It can happen suddenly when the iris is pushed forward, blocking the “angle” of the eye at its inner corner – the drainage meshwork for the aqueous humor to leave the eye. This can spike the IOP and damage the optic nerve. It can also give other symptoms such as:
• Eye pain • Headaches • Nausea and vomiting • Loss of vision • Dilated pupils • Halos or rainbows around light sources • Red eyes • Blurry vision
This suddenly high IOP must be reduced quickly to avoid permanent vision loss. It can be treated by a procedure which removes a tiny part of the outer edge of the iris. This unblocks the drainage canals and allows extra fluid to seep away.
If you have a family history of glaucoma in any form or if you are over about 60 years old, it is important for you to have regular glaucoma testing. Vision lost from glaucoma cannot be restored and if it is left untreated, eventually lead to blindness. Glaucoma is known as the “sneak thief of sight” because symptoms are not noticed until significant vision loss has occurred.
