Dr Dulcy Rakumakoe
5 minute read
25 Feb 2019
12:45 pm

Keep an eye out for glaucoma

Dr Dulcy Rakumakoe

Glaucoma cannot be prevented, but if you diagnose and treat it early, you can control the disease.

Picture: iStock

Glaucoma is a disease that affects pressure within the eye, damaging the optic nerve. This leads to peripheral visual loss.

Glaucoma is one of the leading causes of blindness worldwide, and four in 50 South Africans over the age of 40 suffer from glaucoma.

Glaucoma usually does not produce symptoms until vision is already severely damaged. But if diagnosed early, the disease can be controlled and permanent vision loss can be prevented.

Glaucoma usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.

Glaucoma tends to be inherited and may not show up until later in life. The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to your brain. If the damage continues, glaucoma can lead to permanent vision loss.

Causes

Glaucoma is the result of high fluid pressure inside your eye. This happens when the liquid in the front part of the eye doesn’t circulate the way it should.

Normally, the fluid, called aqueous humor, flows out of your eye through a mesh-like channel. If this channel gets blocked, the liquid builds up. That is what causes glaucoma.

The reason for the blockage is unknown, but doctors do know it can be inherited.

Less common causes include a blunt or chemical injury to your eye, severe eye infection, blocked blood vessels inside the eye, and inflammatory conditions.

It does happen that sometimes eye surgery to correct another condition can bring it on. It usually affects both eyes, but it may be worse in one than the other.

Types of glaucoma

There are two main kinds:

Open-angle glaucoma

This is the most common type. Your doctor may also call it wide-angle glaucoma. The drain structure in your eye, called the trabecular meshwork, looks normal, but fluid does not flow out like it should.

Angle-closure glaucoma

You may also hear it called acute or chronic angle-closure or narrow-angle glaucoma. Your eye does not drain right because the angle between your iris and cornea is narrow. This can cause a build-up of pressure in your eye. It is also linked to farsightedness and cataracts, a clouding of the lens inside your eye.

Risk factors

It mostly affects adults over 40, but young adults, children, and even infants can have it. African-Americans tend to get it more often, when they’re younger.

You’re more likely to get it if you:

  • Are over 40.
  • Have a family history of glaucoma.
  • Have poor vision.
  • Have diabetes.
  • Take certain steroid medications, like prednisone.
  • Have had trauma to the eye or eyes.

Symptoms

Most people do not have any symptoms. The first sign is often a loss of peripheral, or side, vision. That can go unnoticed until late in the disease. That is why glaucoma is often called the “sneak thief of vision.”

Detecting glaucoma early is one reason you should have a complete exam with an eye specialist every one to two years. Occasionally, pressure inside the eye can rise to severe levels. In these cases, you may have sudden eye pain, headache, blurred vision, or the appearance of halos around lights.

If you have any of the following symptoms, seek immediate medical care:

  • Seeing halos around lights,
  • Vision loss,
  • Redness in the eye,
  • Eye that looks hazy (particularly in infants),
  • Nausea or vomiting,
  • Eye pain.

Diagnosis

Your eye doctor will use drops to open or dilate your pupils. Then he/she will test your vision and examine your eyes. He/she will then check your optic nerve, and if you have glaucoma, it will look a certain way.

Narrowed vision (tunnel vision)

Tonometry is a test performed to check your eye pressure. A visual field test, if necessary, is then done to figure out if you have lost your side, or peripheral, vision. Glaucoma tests are painless and take very little time.

Treatment

Treatment is prescription eye drops, laser surgery, or microsurgery.

Eye drops: These either reduce the formation of fluid in the eye or increase its outflow. Side effects may include allergies, redness, stinging, blurred vision, and irritated eyes. Some glaucoma drugs may affect your heart and lungs. Be sure to tell your doctor about any other medications you are taking or are allergic to.

Laser surgery: This procedure can slightly increase the flow of the fluid from the eye for people with open-angle glaucoma. It can stop fluid blockage if you have angle-closure glaucoma.

Procedures include:

  • Trabeculoplasty: Opens the drainage area.
  • Iridotomy: Makes a tiny hole in the iris to let fluid flow more freely.
  • Cyclophotocoagulation: Treats areas of the middle layer of your eye to reduce fluid production.
  • Microsurgery: In a procedure called a trabeculectomy, the doctor creates a new channel to drain the fluid and ease eye pressure.

Sometimes this form of glaucoma surgery fails and has to be redone. Your doctor might implant a tube to help drain fluid. Surgery can cause temporary or permanent vision loss, as well as bleeding or infection.

Prevention

Glaucoma cannot be prevented, but if you diagnose and treat it early, you can control the disease. Usually once you have lost the vision, it cannot be restored.

However, lowering eye pressure can help preserve the sight you still have. Most people with glaucoma who follow their treatment plan and have regular eye exams do not go blind.

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