Glaucoma is the name for a group of eye conditions in which the optic nerve is damaged at the point where it leaves the eyeball.
Glaucoma damage may be caused by raised eye pressure, or because there is a weakness in the optic nerve. In most cases it is usually caused by a combination of both to a varying extent. (Eye pressure is not connected to your blood pressure).
The Two Main Types of Glaucoma
- Primary open angle glaucoma (POAG) also known as chronic glaucoma, is the most common type of glaucoma, whereby the drainage channels slowly become blocked over many years. The eye pressure rises very slowly and there is no pain, but the optic nerve becomes damaged. This initially causes a gradual loss of peripheral vision.
- Acute angle closure glaucoma is much less common. There is a sudden and complete blockage of the aqueous flow, preventing it draining from the eye. It can cause severe pain, blurring, redness of the eye, nausea and cause permanent damage to your sight.
It is treated as an ocular emergency, usually requiring eye drops and surgery.
Your eye needs a certain amount of pressure to keep the eyeball in shape so that it works properly. This pressure is maintained by the continual flow of fluid inside the eyeball. A watery fluid called “aqueous” is produced inside the eye and flows through the eye. It leaves through tiny drainage channels called the trabecular meshwork, where it re-enters the blood stream.
Normally, the amount of fluid produced is balanced by the amount of fluid draining out. However, if it cannot drain properly, or if too much is produced, then your eye pressure will rise.
This high pressure can damage the optic nerve, depending on how high the pressure is, how long it lasts, and whether there is another weakness of the optic nerve.
The Three Tests for Glaucoma;
- Ophthalmoscopy which is a special light used to examine the back of the eye (retina). It focuses especially on the area where the optic nerve leaves your eye (optic disc) and so it can detect any damage.
- Intra Ocular Pressure measurement using a special instrument called a tonometer. This can be with a “puff of air”, or more accurately (as used here and in the eye hospital) with the instillation of eye drops and a blue light.
- Visual Field Test to plot your central visual field with a sequence of lights on a screen. This records any damage to the optic nerve fibres.
If the optometrist finds that the combination of your test results suggests you have or may have glaucoma, they will usually refer you to a hospital eye consultant (ophthalmologist) who can then diagnose your glaucoma and start any treatment you may need. This is usually in the form of eye drops.
If you are concerned with your eyesight and want to have a consultation with your local optometrist, please visit the practice to make an appointment or call to speak to one of our staff members on 0115 933 2999.