WHAT IS GLAUCOMA?

Glaucoma defined: 

Glaucoma is the loss of vision due to pressure that is too high in the eye.  There are several causes, but it is primarily related to age.  Typically, the eye pressure is between 5 to 21 units of pressure.  People who develop pressures above this need to be monitored for this high pressure.  Often, patients may have high pressure without glaucoma.  This is referred to as ocular hypertension. 

There are several forms of glaucoma including:

1.  Chronic Open Angle Glaucoma - This develops over several years.  The angle between the cornea (clear part on the front of the eye) and the iris (colored part of your eye) is normal and NOT narrow.  Thus, the angle is wide open but for some reason, glaucoma still develops.

2.  Acute Angle Closure Glaucoma - This is caused by a narrow angle between the cornea and the iris.  This prevents the fluid from draining out of your eye and increased the pressure rapidly.  This can cause pain and a very red eye.

3.  Normal tension glaucoma - is a form of damage which occurs even though the pressures are below 21.  It can be from debris or pigmentation that closes off the fluid drainage within the eye.

4.  Secondary Glaucoma - can develop from many sources.  Medications, particularly steroids are know to cause glaucoma.  Usually, this takes a long time to develop.  Patients can get glaucoma after having eye irritation - such as an iritis or damage to the eye tissues.  Advanced cataracts (which occur within the lens of your eye) leak lens tissue and can increase the pressure.

How does glaucoma cause damage?

Pressure that is too high in the eye causes damage to their nerve cells (ganglionic cells) in the eye.  These ganglionic cells have a thread like attachment (called axons) that connects to neighboring cells.  Axons are also damaged by glaucoma.

A majority of those affected with glaucoma have open-angle glaucoma.  This type of glaucoma is usually caused by the fluid regulation inside of the eye.  Just behind the front part of the eye (the cornea) is small area called the anterior chamber.  A clear fluid, termed the aqueous humor, is produced within this space for the sole purpose of delivery of nutrients, maintenance of eye shape, and removal of byproducts within the eye. 

After the fluid is produced, it travels to the front of this chamber into a circular channel called the trabecular meshwork.  The aqueous fluid slowly moves out of the eye through this mesh.  Individuals with this common form of glaucoma have problems with this drainage process.  This causes fluid to back up and pressure is increased.

This high pressure collapses blood vessels decreasing the flow of oxygen and nutrients to the nerve cells.  This results in damage to the nerve and vision loss - glaucoma.