Collom & Carney Eye Institute

Glaucoma

GLAUCOMA THE SECOND LEADING CAUSE OF BLINDNESS IN THE U.S.

It is estimated that there are more than 2 million people with glaucoma and 70 million worldwide.  Glaucoma is a group of eye disease characterized by increased intraocular pressure (fluid pressure within the eye) or IOP resulting in damage to the optic nerve and retinal nerve fibers. 

This nerve is like an electric cable.  It contains a million wires, each carrying a message to the brain, which joins together to provide side vision as well as sharp central reading vision.  Glaucoma can produce damage to these "wires", causing blind sports in areas of vision to develop.  Unfortunately, people seldom notice these blind areas in the side vision until considerable optic nerve damage has occurred.  If the entire nerve is destroyed, blindness results.  However, when diagnosed and treated early, blindness from glaucoma is almost always preventable.

There are two major types of glaucoma:

Chronic or primary open-angle glaucoma (POAG). Closed-angle glaucoma. Other variations include congenital glaucoma, pigmentary glaucoma, and secondary glaucoma.

   Open-Angle Glaucoma
 
    

Chronic glaucoma (primary open-angle glaucoma or POAG) is often called "the silent thief of sight" because you have no warning sign, no hint that anything is wrong.  About half of Americans with chronic glaucoma don't know they have it.  The eye receives its nourishment from a clear fluid that circulates inside the eye.  This fluid must be constantly returned to the blood stream by the eye's drainage canal, called the trabecular meshwork.  In the case of open-angle glaucoma, something has gone wrong with the drainage canal.  When the fluid cannot drain fast enough, pressure inside the eye begins to build.  This excess fluid pressure pushes against the delicate optic

nerve.  If the pressure remains too high for too long, irreversible vision loss can occur.

 

Symptoms of open-angle glaucoma:

In early stages, there are no symptons.  There is no pain or outward sign of trouble. Mild aching in the eyes. Gradual loss of peripheral vision (the top, sides and bottom areas of vision). Seeing halos around lights. Reduced visual acuity (especially at night, that is not correctable with glasses).

 

Diagnosing open-angle glaucoma


Your doctor will use tonometry to check your eye pressure.  After applying numbing drops, the tonometer is gently pressed against the eye and its resistance is measured and recorded.  An opthalmoscope can be used to examine the shape and color of your optic nerve.               

The ophthalmoscope magnifies and lights up the inside of the eye.  If the optic nerve appears to be cupped or is not a healthy pink color, additional test will be run.  Perimetry (or visual field examination) is a tests that maps the field of vision.  Looking straight ahead into a white bowl-shaped area, you'll indicate when you're able to detect lights as they are brought into your field of vision.  This map allows your doctor to see any pattern of visual changes caused by early stages
of glaucoma.  Gonioscopy is used to check whether the angle where the iris meets the cornea is open or closed.  This helps your doctor determine if they are dealing with open-angle glaucoma or closed-angle glaucoma.
 
Treating open-angle glaucoma
 
To control glaucoma, your doctor may use medicines, laser surgery and/or filtration surgery.  Medicines may come in pill or eye drop form.  They work by either slowing the production of fluid within the eye or by improving the flow through the meshwork.  Laser trabeculoplasty surgery treats the drainage canal.  Requiring only numbing drops, the laser beam is applied to the trabecular meshwork resulting in an improved rate of drainage.  Filtration surgery  is performed when medicines and/or laser surgery are unsuccessful in controlling eye pressure.  During this microsopic procedure, a new drainage channel is created to allow fluid to drain from the eye.
 


   Closed-Angle Glaucoma
 
Closed-angle glaucoma is much more rare and is very different from open-angle glaucoma.  An accute attack of closed-angle glaucoma, also termed acute angle-closure glaucoma, produces sudden symptoms such as eye pain, headaches, haloes around lights, dilated pupils, vision loss, red eyes, nausea and vomiting.  These signs may last for a few hours, then return again for another round.  Each attack takes with it part of your field of vision.  If not treated promptly, the glaucoma in the eye (IOP) usually goes up very fast when the drainage canals get blocked or covered over.  The iris gets pushed against the lens of the eye, shutting off the drainage angle.  Sometimes the lens and the iris stick to each other.   This results in pressure increasing suddenly, usually in one eye.  Because of the rapid potentially devastating results of closed-angle glaucoma, you should seek medical treatment immediately if you experience any of the above symptoms.
 
Normal visual field Paritally diminished visual field
 
Diagnosing and treating closed-angle glaucoma
 
Diagnosing closed-angle glaucoma is done much like that of open-angle galucoma.  (See diagnosing open-angle glaucoma.) Laser iridotomy is a common treatment for closed-angle galucoma.  During this procedure, a laser is used to create a small hole in the iris, restoring the flow of fluid to the front of the eye.  In most patients, the iridotomy is placed in the upper portion of the iris, under the upper eyelid, where it cannot be seen.  Filtration surgery is performed when medicines and/or or laser surgery are unsuccessful in conrtrolling eye pressure.  During this microscopic procedure, a new drainage channel is created to allow fluid to drain from the eye.
 
   Other Tyeps of Glaucoma
 
It's difficult to spot signs for congential glaucoma because children are too young to understand.  If you notice a cloudy, white, hazy, enlarged or protruding eye, consult your eye doctor.  Congential glaucoma occurs more often in boys than in girls.
 
Pigmentary glaucoma often exhibits no symptoms at all.  You may notice some pain and blurry vision after exercise.  Pigmentary glaucoma affects mostly white males in their mid-30s to mid-40s.
 
Symptoms of chronic glaucoma following an eye injury could indicate secondary glaucoma.
 
 
 
 

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