Glaucoma

“The Thief of Sight”

Glaucoma is a disease that affects up to 3% of the population in the Western World. It is known as ‘the thief of sight’ as up to 50% of those with the disease do not know they have it. Glaucoma causes thinning of the nerve fibre layer in the retina and over time results in a characteristic, gradual loss of vision, with untreated glaucoma leading to blindness.

Signs and Symptoms

Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures. Left untreated, an elevated IOP causes irreversible damage the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision. However, early detection and treatment can slow, or even halt the progression of the disease.

The eye constantly produces aqueous, the clear fluid that fills the anterior chamber (the space between the cornea and iris). The aqueous filters out of the anterior chamber through a complex drainage system. The delicate balance between the production and drainage of aqueous determines the eye’s intraocular pressure (IOP). Most people’s IOPs fall between 8 and 21. However, some eyes can tolerate higher pressures than others. That’s why it may be normal for one person to have a higher pressure than another.

Glaucoma is an insidious disease because it rarely causes symptoms. Detection and prevention are only possible with routine eye examinations. However, certain types, such as angle closure and congenital, do cause symptoms.

  • Angle closure (emergency)
  • Sudden decrease of vision
  • Extreme eye pain
  • Headache
  • Nausea and vomiting
  • Glare and light sensitivity
  • Congenital
  • Tearing
  • Light sensitivity
  • Enlargement of the cornea

The standard tests for glaucoma

Eye Pressure Test

Eye pressure tests are commonly used for testing glaucoma; however, a significant proportion of those who develop glaucoma have normal eye pressures!

Visual Field Tests

Thorough visual field tests show the progression of glaucoma and are vital in monitoring the disease; however, often 25-40% of the nerve fibre thinning has already occurred before a visual field test can pick up a problem.

Optic Nerve Assessment

By careful examination of the nerve head (at the back of the eye), changes can be observed to show glaucoma damage; but these changes often occur after after nerve fibre thinning has already taken place.

The City Eyes Method of Detection and Diagnosis

Because glaucoma does not cause symptoms in most cases, those who are 40 or older should have an annual examination including a measurement of the intraocular pressure. Those who are glaucoma suspects may need additional testing.

The glaucoma evaluation has several components. In addition to the tests outlined above, at City Eyes we also perform a new revolutionary test for glaucoma using the Zeiss GDx nerve fibre analysis machine which can detect glaucoma in the earliest of its stages enabling treatment before loss of vision:

GDx – a new test detecting glaucoma before any loss of vision

A remarkable new glaucoma test has been developed that can pick up nerve fibre layer loss before any loss of vision has occurred.

This test provides an easy to interpret colour map of your retinal nerve fibre layer (RNFL) making the positive early diagnosis of glaucoma routine.

Quick and easy, using an invisible, safe, low powered laser, the GDx scans the nerve fibre layer and compares the thickness of this layer to a database of normal patients. The complete test takes about five minutes with the scan itself taking less than a second.

Stress Free

The GDx is a very sophisticated instrument that takes these measurements painlessly and with no strain on you as a patient. All you have to do is look into the instrument and keep still for one second while you are scanned.

This test is new and currently not covered by the NHS eye examination. As such, a charge may apply.

Who should be tested for glaucoma?

Glaucoma can affect people of all ages and races, however those at greatest risk are:

  • People over the age of 40
  • People of African or Caribbean origin
  • Anyone with high eye pressure
  • Anyone with a family history of glaucoma
  • Diabetics
  • Long term steroid users
  • Anyone who is very short-sighted

Treatment

Most patients with glaucoma require only medication to control the eye pressure. Sometimes, several medications that complement each other are necessary to reduce the pressure adequately.

Surgery is indicated when medical treatment fails to lower the pressure satisfactorily. There are several types of procedures, some involve a laser and can be done in the clinic, others must be performed in the operating room. The objective of any glaucoma operation is to allow fluid to drain from the eye more efficiently.[/one_half]

Your sight is precious

Once you have lost vision with glaucoma you cannot get it back. The best way to preserve your sight is early detection of the disease.

Please discuss this new test with your optometrist or doctor at your next eye examination and they can give you the best guidance and additional information on the GDx and any other tests to help protect your sight.

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