What are the signs and symptoms?

You're more likely to have symptoms with some of the less common types of glaucoma.

Acute angle-closure glaucoma comes on suddenly and the symptoms are often severe. You may:

• Have pain in your eye.
• Have a red, bloodshot eye.
• Feel sick.
• Seeing halos around lights.
• Lose vision in one or both eyes that progresses very quickly.

If you have these symptoms, you need to get to a doctor urgently, as prompt treatment can prevent further damage. However, it's unusual for this type of glaucoma to cause serious loss of vision, simply because it's so painful that people with it don't delay in seeking medical help straight away.

If you have symptoms outside your GP's normal working hours, go to your nearest accident and emergency (A&E) department. The healthcare professionals at A&E will relieve the pressure in your eye and treat any pain.

Secondary glaucoma can cause symptoms too, but because it's caused by other conditions or eye injuries, it can be difficult to tell which are the symptoms of the glaucoma and which are the symptoms of the other condition. For example, an eye condition called uveitis often causes pain and headaches just like glaucoma.  But secondary glaucoma can also have the distinct symptoms of misty vision and rings or halos around lights.

Developmental glaucoma can be difficult to spot because the baby or child may be very young, but again it does have some noticeable symptoms which include:

• Large eyes due to the pressure in the eyes causing them to expand.
• Being sensitive to light (photophobia).
• The eyes look cloudy.
• Watery eyes.
• Jerky movements of the eyes.
• Having a squint, where the eye with poorer vision turns inwards, outwards or upwards, while the other eye looks forward the eye with poorer vision.

If you notice any of these symptoms in a baby or child, visit your GP or optometrist as soon as possible.

Getting tested

Glaucoma can sneak up on you slowly and damage your eyesight without you even noticing. So it's very important to have frequent eye tests - at least once every two years from age 40 onwards and every year if you're at high risk of getting glaucoma. These regular examinations by an optometrist play a key role in picking up the earliest possible signs of glaucoma. Testing can allow doctors to halt the progress of glaucoma if you have it, and so save your eyesight.

There are three tests available for detecting Glaucoma, these are:

• Viewing your optic nerve by shining a light from a special electric torch into your eye.
• Measuring the pressure in the eye using a special instrument.
• Being shown a sequence of spots of light on a screen and asked to say which ones you can see.

If you're more prone to glaucoma than other people then it's even more important to have a regular eye test.

If you have glaucoma, your close relatives (parents, brothers and sisters, and children) should have an eye test every year from the age of 35 years. You should have a sight test even earlier if you're of African-Caribbean origin, or have diabetes or have myopia (short sight).

More information on eye tests for glaucoma

There are three simple tests for glaucoma which should be carried out to reach a diagnosis.

Tonometry

Measuring the pressure in the eye (intraocular pressure) is called tonometry and can be accomplished using several different methods. It is usually carried out by an instrument that gently touches the front of the eye or by blowing a puff of air on to the eye. In the prior case, anaesthetic eye drops are used.

Ophthalmoscopy

Ophthalmoscopy is an examination of the back of your eye using a special lens or torch called an ophthalmoscope. The health of the optic nerve and the retina (the back of the eye where images are focused) are assessed.

Perimetry

The ability to see around you is tested with an instrument called a perimeter. This identifies any gaps or less sensitive spots in your area of vision.

Sometimes, your healthcare professional may also want to measure the thickness of the clear, outer coating at the front of your eye, called the cornea. This is because a cornea that is thicker or thinner than the average can lead to an inaccurate measurement of intraocular pressure.

NHS eye tests

You're entitled to a free NHS eye test if you are over 40 years old and have a first-degree relative (mother, father, sister or brother) with glaucoma.

You may also be entitled to a free NHS eye test if:

• An ophthalmologist (a hospital doctor who specialises in diagnosing and treating eye conditions) thinks that you are at risk of developing glaucoma.
• You are over 60 years old.

When you have a sight test, tell the optometrist if glaucoma runs in your family.

How does the condition progress?

If it's left untreated, glaucoma will continue to damage your eyes and eyesight and can even cause blindness. In fact, it's the leading cause of preventable blindness in the UK.

As a general rule, the higher the eye pressure, the more likely it is that the glaucoma will worsen.

Most people don't notice that they have glaucoma until it's quite advanced because:

• It comes on gradually.
• There are usually no noticeable symptoms or pain.
• One eye can compensate for the other.
• The brain can fill in small gaps (blind spots) in vision so you don't notice that your vision has worsened.

Giving up driving

Glaucoma could affect your ability to drive. If you have glaucoma and your sight in both eyes has been affected, you must by law tell the Driver and Vehicle Licensing Agency (DVLA). You can do this by contacting the DVLA at Drivers Medical Branch, DVLA, Swansea SA99 1TU or phone 0870 240 0009 or inform the DVLA online at www.dvla.gov.uk

The DVLA will then contact your eye specialist for a report. It may also arrange for you to have an examination by a local optometrist. The DVLA will then decide whether your eyesight is good enough for you to carry on driving.