Glaucoma

What is glaucoma really?

Glaucoma is a group of eye-diseases characterised by high pressure levels inside the eye-ball, which progressively damage the optic nerve and its fibres that form part of the retina at the back of the eye. Called by some “the silent thief of sight”, it does not generally cause symptoms until well-advanced.

Left without treatment, it progressively damages vision and may lead to blindness. Although it cannot be cured, it can be monitored and its progression deteained, so as to conserve vision. Therefore the key to protecting your vision is early detection and the correct treatment.

Is glaucoma frequent?

Two out of 100 people over 40 suffer from the disease in Spain, and it causes 12% of blindness in the developed world.

What is ocular pressure?

The aqueous humour is a transparent liquid that fills the eye. It is continually produced by the ciliary body hidden behind the iris that gives colour to the eye. So it must also leave and normally does so via the microscopic pores in the trabecular meshwork. The appropriately balanced quantity of liquid inside the eye provides the correct pressure (generally between 12-20 mmHg.).

The basic concept of glaucoma is that if this pressure is too high it can damage the optic nerve that carries the visual information to the brain. If not treated, this would lead to progressive loss of the visual field and finally blindness.

The aqueous humour enters the eye and leaves, according to the red arrows. When less leaves than has entered, the result is a rise in ocular pressure.

What is the normal ocular pressure?

This refers to a range of 12-21 mmHg. However in some people, a ‘normal’ pressure might be too high and damage the nerve. This is called ‘normal tension glaucoma’ and is diagnosed at our institute more often than would be expected.

On the other hand, in other people a high pressure above 21 mm does not damage the optic nerve. So in glaucoma the key issue is the progressive damage to the nerve which is usually but not always accompanied by high ocular pressure.

ocular pressure

Does blood pressure affect the pressure in the eyes?

No, they are unrelated. High pressure measured in the eyes is independent from blood pressure, usually taken in the arm.

Are there different types of glaucoma?

Yes there are: chronic open angle glaucoma (COAG), by far the commonest, and the rare closed angle glaucoma.

The common type is usually accompanied by high ocular pressure but may also appear as or normal tension (normal-pressure) glaucoma.

Who runs the greatest risk of glaucoma?

It is not related to work or dietary habits or stress or “nerves”. But there are real risk factors to be taken into account:

• Age: Risk increases with age. The disease is rare in people younger than 40, and is typically diagnosed from 50-60 years onwards. For this reason you should have your eyes checked:
  • Once at 35 and at 40 years old.
  • Every 2-4 years after 40.
  • Every 1-2 years after 60.
• Family History: Near relatives of those diagnosed as suffering from CAA glaucoma are 6 times more likely to develop it than those whose relatives are not. Brothers and sisters are exposed to the highest risk, followed by parents and then children.
• High ocular pressure: Typically those above 21 mmHg are under risk, although as mentioned it can appear at below that figure
• Medication : The prolonged use of cortisone drugs (powerful anti-inflammatory medicines widely in use) in the form of drops containing them, inhalers, tablets or injections for inflammation or chronic pain, strikingly raise the probability of developing glaucoma. Unfortunately we see them used unjustifiably for treating minor rashes, irritations and trivial eye complaints. It is important to avoid such self-medication and reject any eye-drops that contain cortisone or its derivatives (dexamethasone, betamethasone, prednisone, fluoromethalone, etc.) that have not been prescribed by an ophthalmologist.