Types of Glaucoma


What is Glaucoma?

Glaucoma refers to a group of different eye diseases which in most cases produce increased pressure within the eye. This elevated pressure is caused by a backup of fluid in the eye. Over time, it causes damage to the optic nerve. Through early detection, diagnosis and treatment, you and your doctor can help to preserve your vision.

Think of your eye as a sink, in which the faucet is always running and the drain is always open. The aqueous humor is constantly circulating through the anterior chamber. It is produced by a tiny gland, called the ciliary body, situated behind the iris. It flows between the iris and the lens and, after nourishing the cornea and lens, flows out through a very tiny spongy tissue, only one-fiftieth of an inch wide, called the trabecular meshwork, which serves as the drain of the eye. The trabecular meshwork is situated in the angle where the iris and cornea meet. When this drain becomes clogged, aqueous can not leave the eye as fast as it is produced, causing the fluid to back up. But since the eye is a closed compartment, your `sink´ doesn´t overflow; instead the backed up fluid causes increased pressure to build up within the eye. We call this open (wide) angle glaucoma.

To understand how this increased pressure affects the eye, think of your eye as a balloon. When too much air is blown into the balloon, the pressure builds, causing it to pop. But the eye is too strong to pop. Instead, it gives at the weakest point, which is the site in the sclera at which the optic nerve leaves the eye.

As we mentioned earlier, the optic nerve is the part of the eye which carries visual information to the brain. It is made up of over one million nerve cells, and while each cell is several inches long, it is extremely thin – about one twenty-thousandth of an inch in diameter.

Primary Glaucoma

Primary open-angle glaucoma is the most common type of glaucoma that U.S. ophthalmologists encounter in glaucoma diagnosis. If you are seeking a new glaucoma evaluation in Madison, Wisconsin the eye doctors at Anderson & Shapiro Eye Care are here to help. Simply call our eye cneter in Madison to arrange a appointment for a complete evaluation. Please are feel free to watch our video on the news with Madison glaucoma expert Michael Shapiro, MD discussing this eye disease.

Primary open angle glaucoma It is a chronic condition, meaning that it develops slowly over time, that usually effects persons over 40 years of age. In POAG, intraocular pressure increases because of improper drainage of aqueous humor from the eye. Open angle means that the problem is not in the canals that carry the fluid back into the bloodstream, but rather in the mechanism that filters the aqueous humor before it enters the canals. This is called the trabecular meshwork and it behaves somewhat like the drain strainer in your kitchen sink.

Variants of Primary Open-Angle Glaucoma

  • Pigmentary glaucoma is an hereditary (genetic) type of glaucoma that occurs when pigment granules in the back of the iris (the colored part of the eye) break off into the aqueous humor inside the eye. These tiny pigment granules gradually cause damage to the trabecular meshwork and raise intraocular pressure.
  • Pseudoexfoliation glaucoma is another type of glaucoma with known genetic underpinnings. It occurs when a flaky material collects and sloughs off the outer layer of the eye's lens and clogs the drainage system for the aqueous humor.

Developmental Glaucoma

In developmental glaucomas, abnormal formation of the ocular drainage structures in the angle of the eye is a cause of IOP elevation.

Secondary Glaucoma

When the eye pressure is higher than normal, this is referred to as Secondary Glaucoma. The trabecular meshwork is the area or angle that filters or drains fluid out of the eye and with secondary glaucoma, the trabecular meshwork is blocked from some abnormality. The blockage can be caused by blood vessels that have grown into the trabecular meshwork or pigment deposits that originate from the Iris. The pressure built up from the fluid that is not flowing rises. Eye Drops can help reduce the amount of fluid produced by the eye and can lower the pressure.

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