What You Need to Know About Acute Angle-Closure Glaucoma
AACG is an eye emergency.
If you’re reading this because you’ve developed a red eye with pain, nausea/vomiting and reduced vision, you should seek medical attention immediately. Resist the temptation to cover the eye, but go straight to a medical professional.
Understanding the eye.
The eye keeps its shape and focuses the light coming in (and therefore the images you see) via the cornea and iris which are filled with fluid. See the diagram above.
The area between the front of the eye and the lens is a watery fluid called the aqueous humour (humour means fluid). And the area in the eyeball, behind the lens is called the vitreous humour. This is more of a jelly-like fluid.
What Causes Acute Angle-Closure Glaucoma?
AACG is an eye emergency and happens when the pressure inside the eye gets too high very quickly. If not treated urgently it can lead to permanent loss of vision in the eye.
There are other types of glaucoma but these happen more slowly and are not discussed here.
What causes AACG? The fluids (humours) in the eye are made in, and drained from the eye so that they are always fresh and clear from the light to pass through. If there is a blockage in the drainage system, the pressure in the eye rises because more fluid is being made but not drained away.
This pressure can start to damage the optic nerve at the back of the eye.
Blockages can occur because of the shape of the eye or structure of it. Therefore some people are more at risk of AACG than others.
Some triggers for AACG can come in situations when the pupil is dilated – such as in dim lighting, after taking certain medications (see below) or in moments of stress or excitement.
Medications to be wary of, and to discuss with your health care professional if you are at risk of AACG are:
- Eye drops that are sometimes to used to dilate the pupil during an eye exam
- Ipratropium (Atrovent) used in COPD or asthma
- Topiramote (Topamax) for epilepsy
- Antidepressants in the tricyclic or SSRI groups of drugs
- Some anti-nausea/vomiting meds
- Phenothiazines used in schizophrenia (eg Thioridazine)
- Some meds used to treat stomach ulcers such as chlorpharmine, cimetidine and ranitidine.
Am I at risk of AACG?
About 1 in 1000 people get AACG. A risk factor is anything that increases your chance of developing a disease. Have risk factors doesn’t mean that you will get the disease and not having risk factors doesn’t mean that you won’t get it.
Risk factors include:
- being over 40 years of age;
- having far-sight;
- being female;
- being of Southeast Asian or Eskimo decent because of the shape of the eye, see above);
- having a close relative (mother, father, brother, sister) who has had AACG.
What are the symptoms of AACG?
Symptoms usually start quite suddenly and include:
- Sudden, severe pain in the eye which might spread round the head, or an aching eye
- Eye redness
- Blurred vision or haloes/circles round lights
- Nausea/vomiting or abdominal pain
- The eye may feel hard and tender.
Sometimes an attack may pass off after a few hours but will probably happen again and each time this happens your vision may be damaged further.
Confirmation of the diagnosis is done by an eye exam with specialised equipment by an eye specialist.
What is the treatment for AACG?
Treatment is needed quickly as this is an emergency.
Resist the temptation to cover the eye – this causes the pupil to dilate which makes the problem worse.
Medical treatment is to lower the pressure and inflammation in the eye by using drops containing betablockers and steroids.
Pilocarpine drops cause the pupil to constrict
Brimonidine eye drops can reduce the fluid in the eye.
Pain killers and anti-nausea meds will help your other symptoms.
When the pressure in the eye has reduced you may need further treatment to prevent it coming back.
If AACG is treated quickly the prognosis for saving the sight is good.
Surgical treatment makes a small triangular hole in the iris (the coloured part of the eye). This is called surgical iridectomy.
Laser treatment involves making a small hole in the iris which allows the fluid to flow freely. This is called peripheral iridotomy.
It may be recommended that you have the same procedure to the other eye to prevent it happening in this eye too.
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