What is Glaucoma

In simple terms, Glaucoma is a build up of pressure in the eye which causes damage to the optic nerve. It is usually painless and the onset of symptoms is so gradual that in the early stages any vision loss can go unnoticed. If undetected and left untreated, Glaucoma can cause blindness. With early detection and treatment however the condition can usually be successfully managed to prevent vision loss.

Glaucoma affects about one in fifty of the population over 40 years of age. As we get older the prevelance rises to about one in ten of the over 70's. There are other factors that also increase the risks such as Diabetes, being of Afro-Carribean origin and having a family history of Glaucoma. Old age however presents the biggest risk.

How does Glaucoma affect my sight

Glaucoma is caused by a build up of pressure within the eye. Pressure is needed within the eye to maintain the shape of the eyeball so that it works properly, a bit like the way a bicycle tyre needs pressure so that it can function. The bicycle tyre pressure is provided by air, in the case of the eye, the pressure is maintained by a fluid. This fluid is also needed to feed the eye and is constantly produced and replaced. Usually there is a careful balance so that as fluid enters the eye it drains out at an equal rate. When this balance becomes upset and the drainage system is too slow, an increase in pressure can occur. This pressure can cause damage to the delicate optic nerve fibres and can result in vision loss.

In rare cases the build up of pressure can be sudden and dramatic. This is known as Acute Glaucoma and causes massive loss of vision and high levels of pain. The much more common form, Chronic Glaucoma, involves a very gradual build up of pressure causing very subtle changes to the peripheral vision. Over time this can be as catastrophic as the acute form causing 'tunnel vision' and if untreated, total blindness.

What are the symptoms

In the early stages of Chronic Glaucoma there are little or no symptoms. There is no pain, discomfort or feeling of pressure. The vision changes come on so slowly and are so subtle that they go unnoticed. Over time the loss of vision becomes greater but because it is the peripheral vision that is affected, tasks such as reading or watching television can still be carried out without any problems and so the condition can still remain undetected. Eventually the damage to the optic nerve becomes so great that even the central vision is affected and in some cases total blindness can ocur. Any vision loss that occurs at any of these stages is irreversible.

Acute Glaucoma is a much less common form of the disease and has a sudden onset which can cause haloes to be seen around lights, intense pain, headache, nausea and a severe blurring of vision.

How will I know if I have Glaucoma

A regular eye examination is the key to early detection of glaucoma. The optometrist will use a battery of tests to check for early signs of the condition, including tests which measure the eye pressure and which check the health of the optic nerve.

How is Chronic Glaucoma treated

The good news is that if caught early the condition can normally be treated successfully and with relative ease. Usually eye drops are prescribed which reduces the pressure and this helps to control the condition. In some cases a minor operation is required. Any damage that has already been caused prior to diagnosis cannot be repaired so early diagnosis, carefull observation and treatment is vital to maintain optimum vision.

How can Glaucoma affect behaviours

Glaucoma mainly affects the peripheral vision. We use our peripheral vision to get around places safely and easily. Finding our way from A to B and avoiding hazzards. It also allows us to pinpoint something in a room, seeing it first out of 'the corner of our eye' before looking directly at it. Peripheral vision also allows us to see objects or people coming towards us so that we can prepare ourselves for their arrival.

Loss of this part of our vision can have an impact on mobility. Being unable to see obstacles or hazzards can cause a loss of confidence especially for elderly people causing them to take tiny steps or feeling their way around for fear of falling. As the condition progresses, walking can become more difficult and this can lead to isolation with the person not wanting to get up from their chair or perhaps prefering to stay in their room where they are in a familiar environment. Communication can be affected, not being able to see they person in the next seat. Frustration levels can grow if objects about a room are difficult to locate. Being unable to see someone approaching with a cup of tea can cause anxiety when they seem to suddenly appear almost like a 'Jack in the box'  right in front.

As always, Glaucoma does not appear in isolation but may be accompoanied by other factors such as old age, frailty, hearing difficulties, other eye conditions or dementia. If we can have an understandig of how it can impact on behaviours we may be able to make adjustments to improve quality of life.