Glaucoma

Glaucoma is a group of diseases that affect the optic nerve, which connects the eye to the brain, and is associated with increased intraocular pressure. There are two forms: chronic and acute. Often both eyes are affected, but usually to different degrees. As most cases have no symptoms, one of the best ways of detecting glaucoma is a routine eye examination – which is why it is important to have regular eye tests.

Glaucoma comes in different types and symptoms will vary depending on which type you have.

• Chronic glaucoma is the most common type of glaucoma, which develops very slowly. If you have chronic glaucoma, it can take a long time before you realise that you have vision problems. This is because chronic glaucoma is painless and usually affects the outer edge of the field of vision and travels slowly to the inner side. Without regular eye examinations, you won’t notice the problem until the glaucoma is near the centre of your visual field.
• Acute glaucoma is a rare condition that can develop suddenly, painfully and painfully when the pressure in the eye increases. Other symptoms may include blurred vision and halos around light sources. Contact an eye specialist or your local emergency department.

Even if the symptoms go away, you should contact an eye specialist as soon as possible, as repeated episodes can damage your vision.

The eyeball contains a fluid called aqueous humour, which is continuously produced by the eye and excess fluid drains through tubes. When the fluid cannot drain properly, it increases the pressure in the eye, also known as intraocular pressure.

Glaucoma develops when increased pressure damages the optic nerve (which connects the eye to the brain) and the nerve fibres extending from the retina (the light-sensitive nerve tissue in the back of the eye). In cases of acute glaucoma, this pressure suddenly increases and causes pain.

Risk factors for glaucoma:

• Family history of glaucoma;
• Age. Chronic glaucoma affects around two in 100 people over the age of 40 and around five in 100 people over the age of 80.
• Higher degree of myopia;
• Increased intraocular pressure, also known as ocular hypertension.

Glaucoma is usually diagnosed during a routine eye examination. The examination will not only assess the general condition of your eye and its structures, but will also include quick and painless tests to help you spot any signs of glaucoma.

Glaucoma tests:

• Eye pressure test (tonometry). An instrument called a tonometer is used to measure the pressure of the eye – intraocular pressure. Tonometry can be useful in detecting ocular hypertension, which is a risk factor for chronic open-angle glaucoma.

• Visual field test. You will be shown a sequence of bright spots and asked which ones you can see. Some spots will appear in your peripheral vision, where glaucoma starts. If you don’t see any spots in your peripheral vision, it may mean that glaucoma has damaged your vision.

• Optic nerve assessment. Your optic nerve connects your eye to your brain. The nerve can be assessed in a number of ways during an examination, including taking photographs using a retinal camera. Digital retinal photography (STF) captures an image of your optic nerve, which can be used in the future to monitor and compare the various changes that occur.

• Optical coherence tomography (OCT). CBCT scans are similar to MRI and ultrasound scans and can help eye specialists detect signs of glaucoma and other diseases up to four years earlier than would be possible with traditional imaging methods. The scan produces a 3D image that gives an even more detailed view of the structure of the eye. Over time, your eye specialist will be able to spot changes that indicate the onset of glaucoma. Check with your local opticians to see if they offer OKT.