Open Sight

What is Glaucoma?

Glaucoma affects one person in fifty after their fortieth birthday with the incidence increasing to one in twenty after sixty-five.

Glaucoma is the name given to a group of conditions in which the optic nerve is damaged where it leaves the eye. This nerve carries the information about what is being seen from the eye to the brain.

A certain level of pressure is needed within the eye for it to keep its shape.

This pressure is maintained by the flow of a fluid (aqueous humour), which is both produced and drains away within the eye and should not be confused with tears.

A balance between the fluid entering and leaving the eye determines the pressure
in the eye (the introacular pressure).

Most cases of glaucoma occur because the flow of fluid out of the eye becomes restricted and the pressure within the eye rises. This pressure causes damage to the optic nerve.
      
In some cases the nerve can be damaged as a result of poor blood supply, weakness of structure or disordered enzymes.

he damage to the nerve causes progressive visual loss. The outer or peripheral vision is the first to be affected. As the loss increases vision is reduced until it is like looking down a tube which is why the term "tunnel vision" is sometimes used.

The loss of vision in glaucoma is permanent, but with early treatment, the damage to vision can be minimised. This may be as simple as using daily eye drops.

The two main types of glaucoma

Primary open angle glaucoma (chronic glaucoma) is the most common form of the condition. 'Chronic' means 'lasting' or 'persistent', and this condition develops slowly over time, without pain. The sufferer is often unaware that they have a problem until their sight is permanently damaged. This is a life-long condition and needs regular treatment and monitoring.

Primary closed angle glaucoma (acute glaucoma) is less common in western countries and more common in people of Chinese or Japanese origin. 'Acute' means 'sharp' or 'severe' and this type of glaucoma is the more dramatic form. Due to drainage problems within the eye the pressure can rise rapidly with the eye becoming hard red and painful. Vision rapidly becomes blurred. With immediate treatment, the sufferer's vision may recover completely, but if there is a delay there will be permanent damage to a varying degree.

Detection

Those in high risk groups should have regular appointments with their optician. Early glaucoma changes can be detected with simple painless tests. These measure the pressure within the eye, check the field of vision to detect untoward changes and note any changes in the shape of the nerve where it leaves the eye.

High Risk Groups

There is a genetic link. Glaucoma tends to run in families, but only some glaucoma patients have affected relatives. If you have glaucoma, close relatives (parents, siblings or children) should have a regular glaucoma test (every year) at a local optician, once they reach the age of 40 years.

• African-Caribbean origin
• Asian Origin
• Diabetes
• Myopia (very short sight).

The risk factors tend to be cumulative so, for a person with several risk factors, testing as early as their 20's may be appropriate.

Treatment

Sight that has been lost through glaucoma cannot be restored, but chronic glaucoma can be controlled and further loss of sight either prevented or appreciably slowed down in the majority of patients.

Treatment is by eye drops, tablets, laser light beam or surgery depending on individual circumstances.