What is Glaucoma?

Glaucoma is a progressive eye disease that results in damage to the optic nerve. Because the optic nerve transmits information from your eye to your brain, glaucoma can result in a gradual, irreversible loss of vision. If left undiagnosed and untreated, it can eventually cause blindness. Fortunately, Glaucoma is a treatable disease and early initiation of treatment can prevent vision loss.

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Primary Open-angle Glaucoma

There are several different types of glaucoma, but the most common is primary open-angle glaucoma (POAG). It is usually painless and has virtually no symptoms, until irreversible damage has occurred. That is why it’s called “the silent thief of sight". High eye pressure, or intraocular pressure (IOP) is often present and is considered a risk factor for glaucoma.

LINK TO VIDEO – OPEN ANGLE GLAUCOMA

Closed-angle Glaucoma

Closed-angle glaucoma, also called angle-closure glaucoma, acute glaucoma, or narrow-angle glaucoma, is glaucoma that is marked by a drainage angle that’s narrower than the normal. It tends to occur in people who are farsighted and those of Asian heritage because their eyes’ anterior chambers are narrower than normal. However, some patients without these risk factors go on to develop closed-angle glaucoma as well.

The anterior chamber is the compartment between the cornea and the iris that contains the trabecular meshwork, which is a mesh-like drainage system of canals that help the eye’s nourishing fluid (the aqueous humor) to pass out of the eye. This meshwork is in the compartment formed between the cornea and the iris.

If that angle is too narrow, fluid can’t drain efficiently. The thickening of the lens, which happens with age, makes the angle even narrower. And the fluid that is prevented from draining creates more of a problem by building pressure behind the iris — in addition to the elevated IOP — narrowing that angle even more. If the pressure gets high enough to push the iris against the trabecular meshwork, it blocks drainage completely, and the result is an angle-closure glaucoma attack. Also known as acute glaucoma, this is a medical emergency. Symptoms may include headaches, eye pain, nausea, rainbows and starburst around lights at night, and blurred vision.

A standard test during a comprehensive eye examination can determine whether you have narrow angle glaucoma. To treat this condition, a small piece of the iris is surgically removed to unblock the drainage canals. This can be done either with laser or conventional surgery.

LINK TO VIDEO – CLOSED ANGLE GLAUCOMA

Normal Tension Glaucoma

Also called low-tension or normal-pressure glaucoma, normal-tension glaucoma is characterized by optic nerve damage that appears to be pressure-related even though it is not accompanied by high eye pressure. No one knows why this occurs, but researchers think it may be related to poor blood flow to the optic nerve. Risk factors for normal tension glaucoma include people with a family history of the disease, those of Japanese descent, and those with a history of systemic heart disease.

Because normal-tension glaucoma, by definition, is not accompanied by high eye pressure, it must be diagnosed by looking for signs of damage to the optic nerve and by checking for peripheral vision loss. Your doctor can scan your eye with optical coherence tomography (OCT) to evaluate the condition of the optic nerve, and perform an ophthalmoscopy, a test that lets the doctor see inside the eye to observe the optic nerve. An optic nerve that’s cupped or not a healthy pink color is a sign of trouble. A visual field test will show the doctor any sight loss that may not be apparent to the patient.

Because the optic nerves of patients with normal-tension glaucoma can be damaged at relatively low levels of IOP16 the condition is frequently treated the same way as “regular” open-angle glaucoma, by lowering IOP with medications and surgery.

Other Types of Glaucoma

Secondary glaucoma, unlike primary glaucoma, is not an original condition but a result of another disease, condition, or event, such as eye injury, eye surgery, advanced diabetes, or advanced cataracts. There are many other causes of secondary glaucoma. A comprehensive eye examination can determine the risks.

Secondary glaucoma can be either open-angle or angle-closure glaucoma, and includes:

• Pigmentary glaucoma is an inherited open-angle glaucoma that tends to affect people with myopia. In the nearsighted eye, the concave shape of the iris creates a wide angle, which causes the pigment of the iris to rub against the lens, break into granules, and clog the drainage canals, causing intraocular pressure (IOP) to rise.
• Pseudoexfoliative glaucoma is when a dandruff-like substance is deposited on the lens of the eye and clogs the drainage system.
• Traumatic glaucoma is a type of open-angle glaucoma that results from an injury that bruises or penetrates the eye. It can occur right after an injury or much later.
• Neovascular glaucoma, is a type of open-angle glaucoma that most often occurs with diabetes. New blood vessels form on the iris and over the eye’s drainage canals, preventing the fluid from leaving the eye and causing a rise in intraocular pressure (IOP).