Acute glaucoma

Acute angle-closure glaucoma, also simply called acute glaucoma, is a disease in which there are sudden increases in the pressure in the eye – intraocular pressure – usually on one side only, with severe pain and loss of vision. Repeated attacks may occur and may progressively reduce the visual field.

There is also a chronic form of this disease, called chronic angle-closure glaucoma, in which the intraocular pressure remains or is raised repeatedly, but with less severe symptoms. In this case the obstruction to drainage of the liquid in the eye (aqueous humor) is gradual.

Cause

This type of glaucoma is caused by acute obstruction of the drainage of the liquid in the eye – the aqueous humor. This is usually due to an anatomic abnormality of the eye in which the front part (anterior chamber) is shallow. This occurs most commonly in an older person who is long-sighted.

An acute attack is precipitated by partial dilatation of the pupil, which blocks the drainage of fluid out of the eye. The pressure inside the eye (intraocular pressure) rises quickly and may be very high.

The pupil dilatation may be caused by poor light, fear, anxiety or medicines, such as certain anti-epileptic drugs.

Who gets it and who is at risk?

Women are more likely to get acute glaucoma than men. It is unusual over the age of 45. Those most at risk are elderly people who are long-sighted.

Symptoms and signs

Symptoms include:

• Decreased vision - the person can often only count fingers held right in front of the face.
• Severe pain in the eye, described as a deep ache in and around the eye
• Nausea and vomiting are common.

The eye is engorged and red – visibly swollen. The surface of the cornea is dull. The pupil does not respond to differences in light – fixed and non-reactive – is semi-dilated and often slightly oval in shape.

Diagnosis

The appearance of the eye can allow the doctor to make a diagnosis.

The intraocular pressure is raised, often to around 60 mm Hg.

Prevention

This disease can be prevented if an eye at risk undrgoes a minor laser procedure called a laser iridotomy.

Treatment

The initial treatment is to lower the intraocular pressure and to constrict the pupil.

Acetazolamide tablet (and sometimes other medication such as Mannitol-intravenously or Glycerol- per mouth) is given to reduce the rate of formation of aqueous humour. Pilocarpine drops are used to constrict the pupil. Topical B-blockers to prevent aqeous production and steroids to decongest the eye.

Nausea is controlled using anti-emetics if necessary.

Painkillers can be used as necessary.

The definitive treatment is surgical. A peripheral iridotomy using a laser (or occasionally surgery) is done. A pinpoint sized hole in the iris is made to allow free flow of fluid between the anterior and posterior chambers of the eye. This is often carried out on the other eye as well, to prevent occurrence.

If the pressure doesn’t control filtration, surgery is done.

When to see your doctor

If you develop a very painful, red and swollen eye and your vision is decreased, you should see your doctor immediately.

Reviewed by Dr L.C. Boezaart, M.B.Ch.B, M.Prax.Med, M.Med (Ophth).

Reviewed by Dr L.Venter, MB Ch B, MMed (Ophth) + FC Ophth SA , December 2010