Open-angle glaucoma, Angle-closure glaucoma, chronic glaucoma, acute glaucoma, what causes glaucoma

Open-angle glaucoma, Angle-closure glaucoma, chronic glaucoma, acute glaucoma, what causes glaucoma

Glaucoma is a group of eye diseases which result in damage to the optic nerve and vision loss.[1]

The most common type is open-angle glaucoma with less common types including closed-angle glaucoma and normal-tension glaucoma. Open-angle glaucoma develops slowly over time and there is no pain.

Side vision may begin to decrease followed by central vision resulting in blindness if not treated.[1] Closed-angle glaucoma can present gradually or suddenly.[2]

The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea.[1][2] Vision loss from glaucoma, once it has occurred, is permanent.[1]

Risk factor for glaucoma include increased pressure in the eye, a family history of the condition, migraines, high blood pressure, and obesity.[1] For eye pressures a value of greater than 21 mmHg or 2.8 kPa is often used with higher pressures leading to a greater risk.[3][2]

However, some may have high eye pressure for years and never develop damage.[2] Conversely, optic nerve damage may occur with normal pressure, known as normal-tension glaucoma.[4]

The mechanism of open-angle glaucoma is believed to be slow exit of aqueous humor through the trabecular meshwork while in closed-angle glaucoma the iris blocks the trabecular meshwork.[2]

Diagnosis is by a dilated eye exam.[1] Often the optic nerve shows a feature known as cupping.[2]a

CAUSES OF GLAUCOMA

GLAUCOMA IS THE SECOND MOST COMMON CAUSE OF BLINDNESS IN THE UNITED STATES.

There are four major types of glaucoma:

  • Open-angle (chronic) glaucoma
  • Angle-closure (acute) glaucoma
  • Congenital glaucoma
  • Secondary glaucoma

The front part of the eye is filled with a clear fluid called aqueous humor.

This fluid is always being made in the back of the eye.

It leaves the eye through channels in the front of the eye in an area called the anterior chamber angle, or simply the angle.glaucoma-example___Source

Anything that slows or blocks the flow of this fluid out of the eye will cause pressure to build up in the eye.

This pressure is called intraocular pressure (IOP).

In most cases of glaucoma, this pressure is high and causes damage to the major nerve in the eye, called the optic nerve.

Open-angle (chronic) glaucoma is the most common type of glaucoma.

  • The cause is unknown. An increase in eye pressure occurs slowly over time. The pressure pushes on the optic nerve and the retina at the back of the eye
  • Open-angle glaucoma tends to run in families. Your risk is higher if you have a parent or grandparent with open-angle glaucoma. People of African descent are at particularly high risk for this disease

Angle-closure (acute) glaucoma occurs when the exit of the aqueous humor fluid is suddenly blocked.

This causes a quick, severe, and painful rise in the pressure within the eye (intraocular pressure).

  • Angle-closure glaucoma is an emergency. This is very different from open-angle glaucoma, which painlessly and slowly damages vision
  • If you have had acute glaucoma in one eye, you are at risk for an attack in the second eye, and your doctor is likely to recommend preventive treatment
  • Dilating eye drops and certain medications may trigger an acute glaucoma attack

Congenital glaucoma often runs in families (is hereditary).

  • It is present at birth
  • It results from the abnormal development of the fluid outflow channels in the eye

Secondary glaucoma is caused by:

  • Drugs such as corticosteroids
  • Eye diseases such as uveitis
  • Systemic diseases