What is glaucoma?
Glaucoma is the name for a number of eye conditions in which the optic nerve is damaged where it leaves the eye. This is usually the result of increased pressure within the eye (intraocular pressure) but may be caused by other factors such as impaired blood supply to the optic nerve. Glaucoma normally affects both eyes but one eye may be more severely affected than the other. It can result in blindness if not detected early.
In Western countries glaucoma affects about two in every 100 people over the age of 40.
There are two main types of glaucoma. Primary (chronic) open angle glaucoma is the most common form of the disease. This type usually develops gradually. It becomes more common with age, mainly affecting older people, but it may occur in early middle age, or at an even younger age, especially if there is a family history of the disease. Open angle glaucoma tends to be more prevalent in people of African/Caribbean origin - in this group it tends to start at a younger age and is usually more severe and less responsive to treatment.
The other less common form of glaucoma is primary (acute) closed angle glaucoma. This type can develop rapidly and is more prevalent in middle aged women and people of Asian origin.
Occasionally, glaucoma may occur as a result of other problems causing an obstruction to the flow of fluid through the eye. Possible causes include eye injury, inflammation, or treatment with steroids. This is referred to as secondary glaucoma.
What are the symptoms of glaucoma?
The onset of acute closed angle glaucoma can be very rapid and may cause headache, eye pain, nausea, vomiting and blurred vision. Rapid treatment is necessary to prevent permanent damage to the optic nerve.
The development of chronic open angle glaucoma is much slower and, because there are often no symptoms in the early stages, damage to the optic nerve may have already occurred by the time the disease is detected. It may be discovered during a routine eye examination or when a person complains of a loss of peripheral vision or blank areas of vision.
What causes glaucoma?
Glaucoma is caused by an increase in intraocular pressure. In chronic open angle glaucoma this pressure damages the optic nerve gradually. In acute closed angle glaucoma, the intraocular pressure rises rapidly, often to high levels, causing pain and redness. There is a hereditary tendency to develop glaucoma. There is no treatment available to prevent the disease occurring but early detection can prevent or limit damage to the nerve as active treatment can be started immediately. Once it has occurred, the tendency to glaucoma remains and ongoing treatment is necessary.
What tests are necessary?
Everyone over the age of 40 should have regular sight tests with an optician every two or three years. There are three tests which are carried out to check for glaucoma: intraocular pressure; optic disc appearance; and visual fields. These tests are painless. The test for intraocular pressure may involve a yellowish green dye being put into the eye temporarily (this washes away naturally). All people who have close relatives with the condition should have regular tests from the age of 35 onwards. Tests are free on the NHS for people over the age of 40 with a family history of glaucoma.
What treatment is available?
Treatment for glaucoma is chosen according to the individual condition and how it reacts to treatment. Initial treatment will usually be with drugs that lower intraocular pressure.
Eye drops containing a beta-blocker such as betaxolol (Betoptic®), carteolol (Teoptic®), levobunolol (Betagan®) or timolol (eg, Timoptol®) may be given. Timolol is also available as an eye gel (Tiopex®). These preparations work by reducing the production of intraocular fluid. They have minimal side effects, although it is possible for some of the medication to be absorbed into the bloodstream. If this occurs the usual action of beta-blockers taken by mouth, such as a lowering of the heart rate or blood pressure, may result. Patients with side effects such as these should be monitored.
Apraclonidine (Iopidine®) or brimonidine (eg, Alphagan®) may also be given. These belong to a group of drugs known as alpha-agonists which decrease intraocular pressure by reducing the production of fluid in the eye and by increasing the outflow of fluid from the eye. Combigan® is a combined preparation containing brimonidine plus a beta-blocker (timolol).
Miotics such as pilocarpine enhance the drainage of intraocular fluid from the eye.
Acetazolamide (eg, Diamox®), brinzolamide (eg, Azopt®) and dorzolamide (eg, Trusopt®) all belong to a group of drugs called carbonic anhydrase inhibitors which work by suppressing the production of intraocular fluid. Acetazolomide is given as tablets or capsules. Brinzolamide and dorzolamide are given as eye drops. Combination products are available containing dorzolamide and timolol (eg, Cosopt®), brinzolamide and brimonidine (Simbrinza®) or brinzolamide and timolol (Azarga®).
Bimatoprost (Lumigan®), latanoprost (eg, Monopost®, Xalatan®) tafluprost (Saflutan®) and travoprost (Travatan®) are another type of eye drops which may be given. These are all prostaglandin analogues which reduce the pressure in the eye by increasing the flow of fluid out of the eye. Combination products containing a prostaglandin analogue and a beta-blocker are available and may be used when a beta-blocker or prostaglandin analogue used alone has not been effective (eg, DuoTrav® [travoprost and timolol], Ganfort® [bimatoprost and timolol], Xalacom® [latanoprost and timolol]).
If drug therapy is not effective other options may be considered, particularly if vision is continuing to deteriorate. Initially, laser treatment may be performed - this can be very effective and does not require a hospital stay. If this is not sufficient, surgery may be necessary. Surgery cannot restore sight unless it has been lost only temporarily, as in acute glaucoma. It can be used, however to prevent further deterioration and loss of vision.
Early detection of glaucoma is the most effective method of controlling the disease.
Further information available from:
International Glaucoma Association
15 Highpoint Business Village
Kent TN24 8DH
Tel: 01233 648170
Fact sheet provided by MIMS
Date last reviewed: October 2008
What is glaucoma?