What is Glaucoma?

The proper definition of glaucoma is a characterised visual field defect caused by damage to the nerves at the back of the eye.

Glaucoma is often mis-defined as high pressure of the eye. High, or raised, intra-ocular pressure (IOP) is a risk factor for glaucoma and is often one of the earliest signs of the condition, though the presence of high IOP does not necessarily mean that there is glaucoma.

Glaucoma usually affects both eyes, though one eye may develop it quicker than the other. Most cases of glaucoma occur due to a build up of pressure in the eye, increasing the IOP which can then ultimately damage the optic nerve (which connects the eye to the brain).

As our understanding of the condition improves, and as the technology that allows us to diagnose it improves, we are able to detect glaucoma at earlier stages than ever before. This is of great benefit when it comes to treatment.

What Will I Notice?

It is unlikely that you will notice any signs of glaucoma yourself, unless it has been present and untreated for many years. Glaucoma affects your peripheral vision and so you will not notice that your vision is getting worse as a result of early glaucoma. This emphasises the importance of regular eye examinations as your optometrist will be able to pick up any signs before you know about it yourself.

How can glaucoma be detected?

Your optometrist will check the appearance of the optic nerve at every eye examination and will check the pressure in your eyes using one of a few techniques. In addition every eye examination includes retinal photographs to monitor the appearance of the optic nerve. OCT scans are included as standard with every private eye examination and are an optional extra for NHS patients. This allows a far more detailed assessment of the structure of the nerve and therefore earlier detection of changes or irregularities.

Visual fields testing (peripheral vision tests) are also recommended to anybody with a family history of glaucoma, or who is thought to be at risk themselves.

Ocular Hypertension

It is possible to have a raised IOP and not have glaucoma. It is however a risk-factor for glaucoma, and one that would often be treated in the same way as glaucoma.

What treatment is available?

Initial treatment for glaucoma usually involves being prescribed eye-drops to try and gradually lower the IOP. If the IOP is very high then it may be decided that it is best for laser surgery (a simple and relatively painless procedure) to be performed to instantly lower the IOP.

If the above treatments do not have the desired effect then other surgical procedures become an option.

Whatever the course of treatment it should be known that the treatment will not repair any damaged nerves. The treatment is given to hopefully slow down any further progression of the condition or to ideally stop it progressing completely.

How often should I get my eyes tested?

A routine, standard eye examination should take place every 2 years at most. This will allow any changes to the IOP or optic nerve to be noted and any necessary action to be taken.

However, if there is an immediate family history of glaucoma (parent, sibling or child) then it will often be advised to have the tests done on a more regular basis.

If you are considered to be at risk of developing glaucoma, or your optician feels they would like to monitor your eyes slightly more regularly than normal they may choose to see you again after 1 year, or sooner if thought best.

Applanation tonometry test for eye pressure