Chronic glaucoma
This page gives you information about chronic glaucoma, the symptoms and treatment.
What is chronic glaucoma?
This type of glaucoma is painless and usually discovered by checks during routine sight tests made by your optician. The pressure of the fluid (aqueous) in the eye damages the sensitive optic nerve which carries visual information to your brain enabling you to see. This causes damage to your vision which is irreversible. In 1 in every 10 people, glaucoma damage happens even though their eye pressure is in the ‘normal’ range – this is called ‘normal tension glaucoma’.
Within the PDF below, see the first figure.
Glaucoma may affect one or both eyes.
What controls the eye pressure?
Watery fluid called aqueous is produced constantly behind the iris (the coloured part of your eye). The fluid circulates through the pupil into the front of the eye and drains away through tiny drainage channels into your bloodstream. Normally the inflow and outflow of the fluid is finely balanced, but in glaucoma there is a build-up of fluid in the eye increasing the pressure to a level which causes damage to the sensitive optic nerve.
The eye pressure does not vary greatly with your blood pressure.
How does glaucoma damage my vision?
Pressure on the optic nerve causes loss in your visual field. The part affected initially is in the shape of an arc slightly above or below your straight ahead vision. As the central vision is the last part to be affected and the sight loss is so gradual, you may not notice a problem until a lot of your peripheral vision is lost.
Without treatment your vision may be severely affected and lead to blindness.
Who gets glaucoma?
There are several groups more at risk:
- Older people - 5% of 65 year olds have glaucoma.
- People of African origin have earlier onset and more severe glaucoma.
- Close relatives of patients with glaucoma have a 1 in 10 chance of developing glaucoma. Relatives over the age of 40 should be checked every 2 years with free NHS checks.
- Short sighted people.
- Migraine sufferers.
- People with Raynaud’s disease (cold hands).
How is glaucoma detected?
Your optician or eye doctor will perform the following tests
- Measurement of the eye pressure. As this varies naturally during the day you may even have to have your pressure taken several times on the same day (called ‘phasing’).
- Assessment of any damage to the optic nerve by looking directly into the eye or using photographs (HRT testing).
- Visual field tests.
All these tests are painless and are used to diagnose and follow the progress of the disease. You will need to have these tests repeated regularly. It may not be possible to arrange all of the tests for the same clinic appointment. It is important that you attend the hospital for these tests.
Treatment
Various treatments are used to lower the pressure in your eyes:
Drops
These lower the pressure in your eye either by reducing the amount of fluid your eye produces, or by improving its drainage from the eye. Your drops should be used regularly as instructed. If you use more than one type of drop - do not put the drops in together. Leave a 5 minute gap between them so that they do not wash each other out. All drops can cause side- effects. Common side effects are redness, irritation and shortness of breath. Report any problems to your ophthalmologist at the hospital. If you have difficulty putting drops into your eyes, please let us know as a special gadget is available free from the hospital to help you. Make sure that you never run out of your drops by asking your GP for repeat prescriptions. Renew the drops every month, but if you have no fresh drops available, continue to use the old ones until you have the fresh ones.
Always use your drops as usual on the days you come for hospital checks. Do not stop using the drops unless instructed by the eye doctor.
Tablets
This is unusual.
Laser
This is sometimes used in elderly patients.
A trabeculectomy operation
For more information about this please ask for a copy of leaflet GHPI0206 ‘Trabeculectomy for the treatment of glaucoma’.
Can I continue to drive?
There are DVLA regulations on fitness to drive. Glaucoma can affect the part of your visual field needed to meet these requirements. There is a visual field assessment designed to test for these legal requirements. If you drive, be sure to ask your clinic doctor if you need one of these tests.
Will my sight get worse?
Glaucoma treatment is used to preserve your remaining vision, it cannot restore lost vision. Low pressures slow the rate of visual field loss. If you are diagnosed early, use your treatment regularly as instructed and attend clinic for review, then the damage to your eyesight will be minimal. You will then maintain and enjoy good vision.
If you have any questions or concerns about glaucoma or your treatment please ask the clinic doctor or optometrist at your next visit.