The term glaucoma refers to a group of eye conditions where the optic nerve (the nerve that carries sight information from the retina to the brain) becomes damaged resulting in impaired vision. It occurs usually as a result of raised intraocular pressure (increased pressure within the eye) which if left untreated can lead to blindness.

Glaucoma is the leading cause of preventable blindness in the United Kingdom and over 500,000 people suffer from it in England & Wales alone. Many more people have elevated intraocular pressure - about 2% of the population age 40-50 rising to 8% of over 70s.

Glaucoma affects people of all ages and all races, though it is most common in the over 40 age group. Most blindness from glaucoma is needless and could have been prevented if detected and treated in time. Most patients have no symptoms from glaucoma. Blindness from glaucoma usually begins with loss of peripheral vision. Central vision is usually maintained until the late stages. By the time the patient notices visual loss, damage is advanced.

Factors which predispose to glaucoma include myopia, black race, and a family history of glaucoma. Thyroid disease, diabetes, and high blood pressure may be associated to some degree.

Intraocular pressure can be measured by a simple test called tonometry. This test is the only reliable method of detecting elevated intraocular pressure and is performed routinely during a Conlons opticians eye examination on all people over 40 and any others deemed to be at risk. There is more than one type of tonometer however generally the non-contact type is used in high street practice - sometimes known as the puff of air test.

Signs of disorders within the eye which could lead eventually to elevated intraocular pressure and glaucoma can be determined by a thorough eye examination. If you are over 40 and have a family history of glaucoma or if you have glaucoma yourself, then this examination is paid for by the NHS.

Because glaucoma has no symptoms until it is too late there are some shocking statistics associated with it. Fully half of all persons with damage from glaucoma are unaware of it, yet in a recent survey blindness ranked third after cancer and heart disease as people's major fear. However, only 20% of people knew that glaucoma was related to elevated pressure within the eye. Another 50% had heard of glaucoma, but weren't sure what it was, while 30% had never heard of it. Of the 20% who knew about glaucoma, most thought either that people affected could tell because they would have symptoms, that it was easily cured, or that it did not lead to blindness.

Despite that fact that glaucoma is roughly as common as high blood pressure and diabetes, the widespread public lack of familiarity with glaucoma results in thousands of people going blind annually, most of which could have been prevented. The best way to prevent glaucoma is to have an eye examination every 2 years. Your optician should be able to answer any queries you might have alternatively for more information you can try:

• Royal National Institute of the Blind
• RNIB Helpline 0845 766 9999 or email: helpline@rnib.org.uk
• National Health Service: NHS
• BBC
• Royal College of Ophthalmologists
• International Glaucoma Association