14420 Visual Field Test

Overview

A visual field test is a painless eye test. It checks how far you can see to the sides when you look straight ahead, and whether any patches of your vision are missing. Your 'visual field' is the whole picture you can see at once — the middle part and the edges. The test draws a map of that picture, showing your doctor which areas you see well and which you may not be noticing. The number 14420 is simply an administrative code used in some health records to label this test, so don't worry if you see it on your paperwork.

Very common. It is one of the standard tests done in eye clinics and is used millions of times around the world each year. Many people have one as part of a routine eye check or before starting certain long-term medicines.

Anyone can be asked to have one, at any age. It is most often done in older adults, people with glaucoma or a family history of it, people with diabetes, people with conditions affecting the optic nerve (the nerve that carries signals from the eye to the brain) or the brain, and people who take certain medicines long-term that can affect eyesight.

Symptoms

Common symptoms

• A visual field test is done to look for problems rather than because of symptoms, so many people have no symptoms at all when they are tested
• Bumping into things on one side, or not noticing people or cars coming from one direction
• Feeling that a patch of vision is blurry, missing, or 'not there', especially off to the side
• Trouble seeing in dim light or at night
• Finding it harder to judge where things are, or feeling less steady when walking
• Being told by others that you did not see something that was clearly there

Symptoms in children

• Bumping into objects or people more than expected
• Tilting the head or turning the whole head to look at things
• Holding things very close, or sitting very near the television
• Seeming to ignore things on one side, or only using one side of a page when drawing or reading
• Children's visual field tests are often done in a simpler, game-like way, and may need to be repeated as your child grows

Symptoms in older adults

• Missing objects or steps on one side, which can raise the risk of falls
• Difficulty in low light, or when moving between bright and dim rooms
• Noticing changes in side vision while driving, such as not seeing a car in the next lane
• Eye conditions that become more common with age, such as glaucoma, cataracts and diabetic eye changes

Causes

Main causes

• Glaucoma — pressure inside the eye damages the optic nerve, and side vision is often affected first
• Damage or inflammation of the optic nerve, such as optic neuritis (swelling of the nerve, often painful)
• Stroke or other problems in the brain that affect the parts that process what we see
• A growth or swelling near the brain or the optic nerve pressing on the pathways that carry signals from the eye
• Problems in the retina (the light-sensitive layer at the back of the eye), such as a detached retina, diabetic eye changes, or inherited conditions
• Some long-term medicines that can affect the retina or the optic nerve, which is why regular testing is sometimes needed
• Thyroid eye disease, or migraine with a temporary change in side vision

Risk factors

• Being older, especially over 60
• A family history of glaucoma
• Raised pressure inside the eye
• Diabetes or high blood pressure
• Being very short-sighted
• A previous eye injury or eye surgery
• Conditions that affect the brain or nerves, such as stroke or a condition affecting the optic nerve
• Taking certain long-term medicines that can affect the eyes
• Smoking

When to see a doctor

See a doctor urgently if:

• You notice a new patch of vision missing, or a curtain or shadow over part of your sight
• Your side vision seems to be shrinking
• You have eye pain, redness or a sudden change in how well you see
• You have new flashes or floaters in your vision
• A child in your care seems to be missing things on one side, or has any change in eyesight

Book a routine appointment if:

• You have been told you need a visual field test and want to understand what it involves
• You have glaucoma, diabetes, or a condition affecting the optic nerve or brain and are due a check-up
• You are taking a long-term medicine and your doctor has said your eyes should be monitored
• You or a family member have a history of glaucoma
• You are finding driving, reading or moving around harder and want your vision checked

Diagnosis

The visual field test is itself the main test. Your eye care professional will cover one eye, ask you to look at a fixed point, and show you small lights in different places. You simply respond when you see one. The machine builds a map of your field of vision for each eye. Your results are then compared with what is normal for your age, and with any earlier tests you have had. The test is not a diagnosis on its own — your doctor puts it together with other checks to understand what is happening.

Tests that may be done

• Confrontation test — a quick bedside check where the examiner moves a finger or target in from the side
• Automated perimetry — the standard machine test such as a Humphrey or Octopus test, where you press a button when you see a light
• Goldmann perimetry — a manual test where a trained person maps your field of vision
• Frequency doubling or short-duration tests — quicker versions used in some clinics or for screening
• Amsler grid — a simple grid you can check at home for changes in the central part of your vision
• Eye pressure measurement and a close look at the optic nerve
• Scanning tests of the optic nerve, such as optical coherence tomography (a scan that measures the thickness of the nerve layer)
• Blood tests or a brain scan, if your doctor thinks another condition may be involved

What to expect at your appointment

The test is quick and painless. You will usually sit in a quiet, dimly lit room at a machine that looks a bit like a large bowl. One eye is covered with a patch, you rest your chin on a support, and you look at a central point. Small lights appear in different places and you press a button each time you see one — even if the light seems faint or far to the side. Some people find it tiring or a little frustrating because the light can be hard to spot; this is normal, and it does not mean you are doing it wrong. You will usually get a short break between eyes. Afterwards, you can drive and go back to your normal day. Ask when and how your results will be shared with you.

Treatment

A visual field test is a test, not a treatment — so the answer to 'what is the treatment' depends entirely on what the test finds. If your field is normal, no treatment is needed and you may simply be checked again in a year or two. If something is found, your doctor will discuss options aimed at protecting your sight and treating the underlying cause.

Self-care at home

• Bring your glasses or contact lenses to the test, and wear them if you are asked to
• Try to be well rested and avoid having the test when you are very tired
• Take your time, blink normally, and don't worry about occasional misses — the machine accounts for them
• Ask for a break if your eye or neck feels uncomfortable
• Keep a simple note of any changes you notice between appointments, such as bumping into things on one side
• Keep up with regular eye checks, even if you feel fine

Medical treatments

Treatment depends on the cause. For glaucoma, the aim is to lower the pressure inside the eye — this is usually done with eye drops prescribed by your eye specialist, and sometimes with laser treatment or surgery. For inflammation or other nerve problems, your doctor may prescribe anti-inflammatory medicines. If a condition such as diabetes or high blood pressure is involved, good control of that condition is an important part of protecting your sight. For vision that has already been affected, low-vision aids such as magnifiers, special lighting and advice from a low-vision service can make daily life much easier. Always follow the plan your own healthcare team gives you, and never start, stop or change any medicine without talking to them first.

When is surgery considered?

Surgery is only considered if the test helps find a problem that surgery can help with. Examples include laser or other surgery to help fluid drain from the eye in glaucoma, cataract surgery, repair of a detached retina, or, rarely, surgery to relieve pressure on the optic nerve from a growth. Your specialist will explain the benefits and risks, and whether surgery is likely to help in your situation.

Living with this condition

Most people have a visual field test and carry on exactly as before. If the test shows that part of your side vision is affected, a few practical changes can help a lot: use good lighting at home, keep floors and stairs clear, mark the edges of steps, turn your head slightly to scan around you, and arrange furniture so pathways stay open. If you drive, you must meet the vision standards where you live — tell your licensing authority if a health professional has told you that your vision may not meet the standard, and ask your eye team for advice. Regular reviews help you and your doctor see the whole picture over time.

Lifestyle tips

• Have your eyes checked at the intervals your optician or eye clinic recommends
• If you smoke, stopping is one of the best things you can do for your eyes and blood vessels
• Keep blood pressure and blood sugar within the range your doctor advises
• Wear protective eyewear for DIY, sport and hazardous work
• Use brighter, well-placed lighting at home, especially on stairs and in the kitchen
• Tell family or friends if you are missing things on one side, so they can help spot what you might not see

Diet and exercise

There is no special diet that replaces eye checks, but eating a varied, balanced diet rich in vegetables, fruit and oily fish supports the health of your eyes and blood vessels. Regular activity — such as walking, swimming or cycling — helps blood pressure and blood sugar, which matters for eye health. If you have a particular eye condition, ask your specialist whether there are any activities you should avoid, as advice can differ from person to person.

Mental health and emotional wellbeing

Being told you need an eye test, or finding out that your vision has changed, can bring up worry, sadness or anxiety. That is completely understandable, and you do not have to cope alone. Talking to your GP, your eye team, or a counsellor can help, and many sight-loss organisations offer emotional support and practical advice. If you ever have thoughts of harming yourself, contact your local emergency number or a crisis support service in your country straight away.

Prevention

You cannot prevent needing a test — it is a check, not an illness. But you can greatly improve your chances of catching any problem early, which is when treatment works best. Regular eye checks are the single most useful habit, especially if you are over 60, have a family history of glaucoma, or have diabetes.

Screening programmes

Many countries offer routine eye checks through an optician, and some offer free or reduced-cost checks for people at higher risk. If you have diabetes, regular diabetic eye screening is usually recommended. If glaucoma runs in your family, tell your optician — you may be offered more frequent checks. Ask your local eye service what applies to you.

Complications

If left untreated

• Slowly worsening side vision, which can go unnoticed until a lot has been lost
• In glaucoma, permanent damage to the optic nerve and, if never treated, serious sight loss
• Difficulty driving, reading or moving around safely, and a higher chance of falls
• Delays in finding conditions such as a detached retina, a stroke or pressure on the optic nerve, when early treatment helps most

Long-term outlook

The outlook is generally good. Most people who have a visual field test get a normal result. When something is found, it is often at an early stage, and many eye conditions can be slowed or managed with treatment and regular monitoring. The test is a tool that helps you and your doctor act early — which is exactly what gives the best chance of protecting your sight.

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