There are several forms of glaucoma, but two common forms are open-angle and closed-angle glaucoma. Both are caused by a disruption in the drainage of aqueous humor.
What is Aqueous Humor?
Aqueous humor is a clear fluid produced within a ring-shaped tissue (ciliary body) beneath the iris that encircles the lens of the eye. The secreted fluid flows behind the cornea and around the iris and then out through a spongy layer of drainage channels.
Aqueous Humor & Eye Health
The cornea and lens of your eyes are clear. They have no blood vessels and so rely on the aqueous humor for oxygen and nutrients and your eye uses the hydrostatic pressure of the aqueous fluid to maintain shape and proper intraocular pressure.
This continual secretion and flow and drainage of aqueous humor is crucial to the health of your eyes. Aqueous humor keeps the cornea and lens oxygenated, removes waste products, and keeps the eye inflated.
What is the “Angle”?
Between the cornea and iris there is an angled opening that the aqueous humor flows around and then out through a spongy network of channels at the base of the cornea.
When the angled opening is closed because the outer rim of the iris is pressing against the lens then fluid will build up behind the iris and rapidly increase intraocular eye pressure.
This is also known as angle closure glaucoma.
This type of glaucoma is less common. It can be a gradual closure or an acute (sudden) closure. If it is an acute case, some of the following symptoms will occur:
- Sudden, severe eye pain
- Blurred vision
- Halos around objects
- Nausea or vomiting
- Eye tenderness, hardness, and redness
Acute closed-angle glaucoma is a medical emergency. Call 911 or go to an ER for treatment. Without treatment, vision loss can occur within a day of the onset of symptoms.
The emergency treatment for acute closed-angle glaucoma is usually laser or conventional surgery to remove a small portion of the bunched-up outer edge of the iris to unblock the drainage opening.
This is the most common type of glaucoma in North America. In this type, the channel between the iris and lens is open, but the drainage through the spongy trabecular meshwork is impeded which will slowly raise intraocular eye pressure and untreated, will damage the optic nerve.
The treatment for open-angle glaucoma is to lower the intraocular eye pressure. That is done with either eye drops that increase the amount of fluid that drains, or ones that decrease the amount of fluid your eye makes, and some that do both.
If eye drops are not effective for you, oral medications or surgery may help. There are several types of laser and conventional surgeries that open blocked drainage channels.