With the exception of acute glaucoma (see below) there are no symptoms of glaucoma until very late.
Glaucoma is often called the “sneak thief of sight” as you lose vision without realising it. This is because it affects the side vision first and then slowly works its way inwards to cause ‘tunnel vision’. Eventually the ‘straight ahead’ vision is also lost leading to blindness.
Sadly the damage done from glaucoma cannot be reversed so it is important to prevent vision loss from occurring in the first place. Thankfully with treatment vision can be saved for most people.
Who is at risk of glaucoma?
Anyone can get glaucoma however the following factors increase your risk:
- Increasing age: although glaucoma can affect you at any age, it is much more common as you get older, particularly over 60 years.
- Family history: If you have a parent, brother or sister with glaucoma you risk is increased.
- Ethnicity: Glaucoma is common in Caucasians, Asians and Indians. It is less common in Polynesians and Maori.
- Short-sightedness or long-sightedness
- Previous eye injury
- High blood pressure
- Past or present use of steroid treatment
When should you be checked for glaucoma?
The only way to detect glaucoma early is to have regular eye examinations. If you have risk factors for glaucoma your first eye check should be no later than the age of 40 years. If you don’t have risk factors then no later than the age of 45 years is recommended.
What are the different types of glaucoma?
Primary Open Angle Glaucoma (POAG)
In New Zealand this is the most common type of glaucoma. This is a chronic (long-term) disease that occurs slowly. Although the drainage part of the eye is open it does not work well leading to a gradual build-up of fluid in the eye. This causes high eye pressure that damages the optic nerve. The exact cause of POAG remains unknown.
Normal Tension Glaucoma (NTG)
In this type of glaucoma the optic nerve is damaged even though the eye pressure is normal. People with NTG may have a very sensitive optic nerve or the blood supply to the nerve may be affected. This is also a chronic disease that occurs slowly.
Ocular Hypertension (OHT)
This is a condition where the eye pressure is high but there are no signs of glaucoma yet. Patients with OHT are at risk of developing glaucoma and sometimes need to be treated to lower the eye pressure back to normal.
Acute (angle closure) Glaucoma (ACG)
This occurs when fluid builds up behind the iris causing it to bulge forwards suddenly blocking the drainage part of the eye. This leads to a very rapid (hours) rise in eye pressure and is an emergency as damage to vision occurs in a very short time. An attack of acute glaucoma causes severe eye pain and redness, nausea and vomiting, blurred vision and/or halos around lights. Urgent laser treatment is needed to treat this condition (see below).
This is when glaucoma develops as a result of another condition in the eye such as trauma, inflammation, or diabetes. Other types of glaucoma in this category include pseudoexfoliative glaucoma and pigmentary glaucoma.
People who have a narrow drainage angle because of the shape of their eye are at risk of this condition and need laser treatment to prevent ACG.
How do we diagnose glaucoma?
At Eye Surgery Associates you will have a comprehensive eye assessment in which the most advanced technology currently available is used to check for glaucoma. You can expect the following to be performed:
Eye and medical history
Eye exam including:
- Vision test
- Slit-lamp microscope exam of the front of your eye
- Measurement of your eye pressure
- Measurement of corneal thickness (this can affect eye pressure)
- A look at the drainage part of the eye using a special lens
- Dilated pupil exam to look into the back of your eye at the optic nerve and retina
Visual field testing:
this is a computerised test that maps out your entire field of vision to see if there are any missing patches. This is the best way to pick up the early loss of side vision that is seen with glaucoma.
Optical Coherence Tomography (OCT):
this is a special optic nerve scan that can detect the earliest changes of glaucoma. This allows very early diagnosis as well as precise monitoring for glaucoma. At Eye Surgery Associates we use the Spectralis OCT provided by Heidelberg Engineering of Germany.
this provides a three-dimensional photograph of the optic nerve that is also used to help us monitor you for glaucoma.