Glaucoma

Glaucoma is the name for a group of eye conditions in which the optic nerve is damaged by raised pressure within the eye.

Representation of the effect of glaucoma

Some parts of the eye, such as the lens, are nourished by a watery fluid called the aqueous humour. This fluid is produced and circulated around the eye and then drains away through channels near the front of the eye.

If the fluid cannot drain away, or too much is produced, the pressure rises. This eye pressure is quite different from blood pressure.

Chronic Simple Glaucoma is the most common type of the condition, affecting about 1 in 100 people over 40 in the U.K.

Sight may be affected in one of two ways:

• The extreme edge of the field of vision may start to fade, causing vision to narrow or
• blank areas may develop closer to the centre of vision.

As the pressure in the eye usually increases very slowly, the loss of vision is slow, taking months or even years before it becomes really noticeable. The side vision is affected and so a person will still be able to read and may not be aware of what is happening. It is usually discovered at a sight test and all people over 40 should make sure their sight test includes a test for glaucoma.

Glaucoma often runs in families and the test is free to those over 40 who have a blood relative with the condition. It is important to diagnose glaucoma early as treatment can prevent further deterioration.

Tests are straightforward and painless. There are three main tests that are used:

• Ophthalmoscopy: In this test, the appearance of the area where the optic nerve leaves the back of the eye is examined using a special hand held instrument. This gives a result that is sufficient for glaucoma screening.
• Either a gentle puff of air is blown against the eye, or a small instrument is placed gently against the eye after the eye has been numbed by drops.
• Perimetry: this is a test that may be done to see if there are any gaps in the field of vision.

The use of all three tests ensures the best chance of early detection of glaucoma.

Living With Glaucoma

• Lighting is all important - strong but not glaring
• Sunglasses will help on bright days
• Consider wearing a visor or hat with brim
• White Symbol Cane can be useful for difficult times such as dim light
• Colour Contrast may help you to see things easier
• Magnifiers may be useful - ask at your local Low Vision Aids clinic
• Typoscopes may help when reading to help keep to the line and to cut down on glare

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