Eye Diseases Glaucoma

Glaucoma is a disease caused by increased pressure in the eye due to blockage in the flow of the aqueous humor, the liquid in the eye.

Normally, the aqueous humor is produced in the ciliary body, a ring of tissue behind the iris. From there, it flows into a location known as the posterior chamber, a small spot in the eye between the iris, the ciliary body and the actual eyeball.

During normal eye function, the aqueous humor flows from the posterior chamber to the anterior chamber, in front of the lens but behind the cornea. (This region is known as the anterior chamber.) From there, it passes through a thin layer of tissue on the eyeball to the canal of Schlemm and into surrounding blood vessels.

Blockage arises when the aqueous humor is unable to pass through these intricate parts of the eye smoothly. These obstructions inevitably cause pressure to build in the posterior chamber, putting pressure on the optic nerve and the retina. Pressure or damage to these areas causes vision problems.

Glaucoma

Some of the reasons that the aqueous humor becomes blocked include:

  • eye injuries
  • inflammation in the eye
  • the presence of tumors.

Acute Glaucoma

In some people, the outer rim of the iris is very close to the eyeball. When these people develop a blockage, the pressure builds up on the back of the iris, potentially forcing the outer part of the iris against the eyeball. When this happens, the aqueous humor has no outlet and is forced into the canal of Schlemm. In these cases, acute glaucoma, or narrow-angle glaucoma, results.

Acute glaucoma refers to a type of glaucoma in which the symptoms are brief, yet intense, and clear up on their own. If the pupil contracts, the pressure can be released. The most common time for the pupil to contract is during sleep. During sleep, the blockage is cleared, and the aqueous humor begins to flow again.

Chronic Glaucoma

When the blockage of aqueous humor occurs in the thin layer of tissue between the anterior chamber and the canal of Schlemm, it is considered a continuous blockage. These cases result in chronic glaucoma.

Optometrists diagnose chronic glaucoma when they observe high intraocular pressure caused by a blockage. In some cases, the pressure from blockage can leave an actual mark on the optic disk, where the optic nerve connects to the eyeball.

Studies show that chronic glaucoma affects about one percent of older Americans and as much as 10 percent of the population older than 80.

Although it is also rare among those younger than 40, individuals who have relatives with glaucoma are up to five times more likely to develop the disease than others, regardless of age.

Chronic glaucoma is also more common among African Americans over 40 and Mexican Americans older than 60. For these people and those related to someone with glaucoma, doctors recommend a comprehensive eye exam at least every two years.

Symptoms of Glaucoma

Chronic glaucoma typically causes no symptoms or pain in its early stages.Over time, those with chronic glaucoma may lose peripheral vision.

Patients with narrow-angle or acute glaucoma can sometimes detect symptoms of their disease. Common symptoms linked to acute glaucoma include:

  • headaches
  • nausea
  • seeing halos around lights
  • vomiting.

Other Types of Glaucoma

Other types of glaucoma include:

  • congenital glaucoma, which exists in babies born with a defect that prevents normal flow the aqueous humor
  • juvenile glaucoma, which occurs in children and young adults
  • neovascular glaucoma, which is caused by abnormal blood vessel growth that creates pressure in the eye
  • pigmentary glaucoma, a condition in which the iris begins to flake off and create blockages.

Glaucoma Treatment

Treatment for chronic glaucoma usually involves reducing intraocular pressure with miotic drugs in the form of eye drops. These chemicals cause the pupil to contract and allow the aqueous humor to resume its natural flow through the eye. For acute cases of glaucoma, treatment can be similar to that for chronic cases.

Surgery is currently the only option for a permanent solution to the high pressure. During these procedures, surgeons create an opening in the edge of the iris to create a pathway through which the aqueous humor can flow smoothly.