Glaucoma is not just one eye disease, but a group of eye conditions resulting in optic nerve damage, which causes loss of vision. Abnormally high pressure inside your eye (intraocular pressure) usually, but not always, causes this damage.

Glaucoma is the second leading cause of blindness.2% of people over the age of 40 have or will have glaucoma. Sometimes called the silent blinder, glaucoma can damage your vision so gradually you may not notice any loss of vision until the disease is at an advanced stage. The most common type of glaucoma, primary open-angle glaucoma, has no noticeable signs or symptoms except gradual vision loss.

Early diagnosis and treatment can minimize or prevent optic nerve damage and limit glaucoma-related vision loss. It's important to get your eyes examined regularly, and make sure your eye doctor measures your intraocular pressure.

Symptoms
The most common types of glaucoma — primary open-angle glaucoma and acute angle-closure glaucoma — have completely different symptoms.

Primary open-angle glaucoma signs and symptoms include:

Acute angle-closure glaucoma signs and symptoms include:

Both open-angle and angle-closure glaucoma can be primary or secondary conditions. They're called primary when the cause is unknown and secondary when the condition can be traced to a known cause, such as eye injury, inflammation, tumor, advanced cataract or diabetes. In secondary glaucoma, the signs and symptoms can include those of the primary condition as well as typical glaucoma symptoms.

When to see a doctor
Don't wait for noticeable eye problems. Primary open-angle glaucoma gives few warning signs or symptoms until permanent damage has already occurred. Regular eye exams are the key to detecting glaucoma early enough for successful preventive treatment.

Glaucoma

Aqueous humor continuously circulates from behind the iris into the anterior chamber at the front of the eye. It exits where the iris and the cornea meet. The fluid filters through a spongy tissue containing microscopic channels (trabecular meshwork) before passing into a larger channel called Schlemm's canal, where it eventually merges with the bloodstream.