Glaucoma is the name given to a group of conditions in which the optic nerve suffers a characteristic form of damage at the back of the eye that is often associated with a raised level of intraocular pressure. It can cause irreversible vision loss if left untreated. Fortunately glaucoma is easily treated with eye drops if diagnosed early but despite this it is still one of the biggest causes of blindness in the developed World.
Your eye needs a certain amount of pressure to keep the eyeball in shape so that it works properly. However, if the optic nerve comes under too much pressure then it can be damaged. The amount of damage there is depends to a certain extent on how high the pressure is and how long it lasts, and whether there is a poor blood supply or other weakness of the optic nerve. A really high eye pressure can damage the optic nerve immediately. A lower level of pressure can cause damage more slowly, and then you would gradually lose your sight if it is not treated. Having said that, there is an increasing number of patients that have glaucoma but do not have high pressures at all. These patients possibly have a pre-disposition to sustaining damage to the optic nerve at pressures usually considered to be normal. It is not entirely clear why this happens, possibly genetic or possibly related to poor blood circulation at the back of the eye.
The damage may be caused by raised eye pressure or you may have an eye pressure within normal limits but the damage occurs because there is a weakness in the optic nerve. In most cases, high pressure and weakness in the optic nerve are both involved to a varying extent (Eye pressure is not connected to your blood pressure). However, there are a significant number of people who have raised intraocular pressure but do not have glaucoma. The normal range of eye pressure is up to 21mmHg. If your eye pressure is above 22mmHg, you will generally be told that you have ocular hypertension. This is not the same as having glaucoma.
A diagnosis of glaucoma means that the pressure in the eye has caused some damage to the optic nerve but a diagnosis of ocular hypertension may mean your pressure is higher than normal but there isn’t any damage to your optic nerve. Only a minority (about 10%) of people with ocular hypertension will go one to develop glaucoma, unfortunately there is currently no way of telling who will develop glaucoma and who won’t.
The optic nerve damage causes patchy loss of vision that varies in severity from patient to patient. Most patients with glaucoma are not aware of problems with their vision. This is because the damage that occurs with glaucoma has a slow time course and the central vision (for reading and recognising people) is only affected when glaucoma has advanced to a late stage.
Without treatment, the loss of vision in glaucoma is permanent, but with early treatment, the damage to vision can be minimised.
Even when central vision is still good, glaucoma may affect the vision needed for driving and getting about (for instance, seeing steps). Blindness from glaucoma is rare. If blindness does occur, it is usually because the glaucoma is already advanced when it is first diagnosed, because the eye pressure has not responded well to treatment or because patients have not taken their drops regularly.
Risk factors other than high eye pressures include increasing age, being short sighted, having a first degree family member with glaucoma (particularly siblings) and being diabetic.
If you are concerned about glaucoma or have been identified as being at risk we can provide a NICE compliant diagnostic examination performed by Dr Adrian Jones that will provide you with an diagnosis and treatment if required.
Alternatively, if you already have been diagnosed with glaucoma and no longer want to have the inconvenience of attending the hospital for your follow up visits, we are able to provide NICE compliant follow up at a time that is convenient to you.
We comply fully with the recently published guidelines from the National Institute for Health and Clinical Excellence on diagnosing, treatment and monitoring of patients with glaucoma or whose at risk of developing the disease.
For more in depth information about glaucoma visit the International Glaucoma Association website.