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Visual Field Test (Perimetry): What It Is, How It Works and Tips for Taking It
A visual field test, also called perimetry, measures how much you can see around the point you are looking at: your central and your side (peripheral) vision. You stare at a fixed target and press a button every time a small light flashes. It is one of the main tests for finding glaucoma and for checking the optic nerve, and it can also show problems in the retina or the brain's visual pathway. At Laser Istanbul Clinic your surgeon reads the result with you.
A visual field test (perimetry) maps your central and side vision by asking you to press a button each time you see a small flash of light while you keep your eyes on a fixed point. The common Humphrey test takes about 5 to 10 minutes per eye. It finds and tracks glaucoma and other optic nerve, retina and brain conditions. At Laser Istanbul Clinic, Prof. Dr. Ahmet Satıcı, Doç. Dr. Muhammet Derda Özer or Op. Dr. Aysan Bayram reads your result.
What a visual field test measures
Your visual field is the whole area you can see at once while your eye stays still, including everything off to the sides, above and below. Guy's and St Thomas' NHS Foundation Trust describes a visual field test as a check of how well you see across your whole area of vision, central and peripheral, and says it helps doctors diagnose and monitor conditions of the retina, the optic nerve and the visual pathways through the brain.
The test does not measure how sharp your vision is. You can read the bottom line of the chart and still have a large patch of missing side vision. That is why the test matters: the UH Sussex NHS leaflet notes that a loss of peripheral vision can make driving unsafe even when a person has 20/20 central vision.
What a visual field test can show:
- Where your vision is reduced or missing, point by point, in each eye
- How deep the loss is: a faint dimming or a fully blind patch
- The pattern of the loss, which points towards the cause. Glaucoma typically causes arcuate (arc-shaped) defects, nasal steps and small paracentral blind spots that follow the nerve fibres of the retina, according to a Community Eye Health guide by David Broadway
- Change over time, when the test is repeated using the same method
Types of visual field test
| Test | How it works | Typical use | Time |
|---|---|---|---|
| Humphrey automated (static) perimetry | A bowl-shaped machine flashes stationary lights of different brightness at set positions; you press a button when you see one | Glaucoma, optic nerve disease, most day-to-day monitoring | About 5 to 10 minutes per eye (Guy's and St Thomas'); 3 to 5 minutes in some clinics (UH Sussex) |
| Goldmann (kinetic) perimetry | A technician moves a light inward from the far edge until you see it, mapping the edge of your field | Neurological problems, people who find the automated test too difficult | Up to 30 minutes per eye (Guy's and St Thomas') |
| Esterman binocular test | Both eyes are tested together to judge everyday functional vision | UK driving assessments (the DVLA requires a binocular Esterman test) | Done at a DVLA-contracted optician |
| Confrontation test | The examiner holds up fingers or a target at the edge of your vision | Quick bedside screening, not a full measurement | A few moments |
| Home tablet perimetry | A tablet shows lights and you tap when you see them | Extra monitoring between clinic visits | See "Visual field test online" below |
The Humphrey visual field test
The Humphrey Field Analyzer is the most commonly used instrument for visual field assessment worldwide, according to a 2025 review in Survey of Ophthalmology. Its standard "24-2" pattern tests 54 points spaced 6 degrees apart, covering the central 24 degrees of vision (plus two points near 30 degrees on the nose side). The "10-2" pattern tests 68 points only 2 degrees apart inside the central 10 degrees, and is used when the doctor needs a finer look at the centre of your vision.
The machine runs on a computer method called SITA (Swedish Interactive Thresholding Algorithm), which finds the dimmest light you can see at each point with fewer flashes than older methods. The same review notes that SITA cut testing times by about 50% compared with older full-threshold testing, and that the newest version, SITA Faster, shortens a 24-2 test by about a further 30% compared with SITA Fast. Our examination uses {{perimeter models used by your surgeons}}.
Why you may need a visual field test
A visual field test is needed whenever your doctor suspects or already knows that something is damaging the pathway from the retina to the brain. The main reasons are these.
1. Glaucoma. The US National Eye Institute (NEI) describes glaucoma as a group of eye diseases that damage the optic nerve. Side vision is lost first, starting with the part closest to your nose, and half of people with glaucoma do not know they have it. A visual field test is part of the standard check, and NEI is clear that treatment cannot undo damage but can stop it getting worse. That makes the field test both a diagnosis tool and the main way to see whether treatment is working. The Community Eye Health guide says repeat testing is vital in glaucoma, using the same method each time so that results can be compared.
2. Optic nerve and brain conditions. The UH Sussex leaflet lists glaucoma, the effects of a stroke, drooping eyelids and other neurological problems among the reasons for a visual field test. The shape of the missing area helps your doctor decide where to look for the cause. Sudden loss of vision or a new patch of missing sight is an emergency and needs same-day assessment by a local eye casualty service or hospital, not a booked test.
3. Retinal disease. Damage to the retina leaves matching blind areas in the field. Your retina surgeon uses the field result alongside scans.
4. Eyelid problems. When the upper lids droop or loose skin hangs over them, they can block the top of your vision. EyeWiki (American Academy of Ophthalmology) notes that a visual field is usually requested to show how a drooping lid affects your peripheral vision.
5. Planning surgery. If you have glaucoma or optic nerve damage, your surgeon needs a recent field to judge how advanced the damage is, to choose between drops, laser and surgery, and to set a baseline against which later checks are compared. Knowing your field before any eye operation also helps your surgeon give you realistic expectations about what surgery can and cannot improve.
What to expect: the Humphrey visual field test step by step
- A short explanation. A technician explains the test and may offer a practice run. Ask any question now; it is much harder to ask mid-test.
- Positioning. You sit at a bowl-shaped machine with your chin on a rest and your forehead against a support. One eye is covered; the other is tested.
- Look at the centre. You keep looking at a small orange dot in the middle of the bowl for the whole test. You do not look around for the lights.
- Press the button. The machine flashes small lights of different brightness at different places and times. You press the button each time you notice one, even if it is very faint.
- The other eye. The cover moves and the whole test is repeated for the other eye.
Is it painful? No. Nothing touches your eye.
How long does it take? Guy's and St Thomas' quotes 5 to 10 minutes per eye for the Humphrey test. UH Sussex says 3 to 5 minutes per eye. The exact length depends on the test type and on how you respond. Allow more time than the test itself, because of the explanation, breaks and any repeat.
Do I need to prepare? The NHS leaflets mention no special preparation. Bring all your glasses, including reading glasses.
Do you wear glasses for a visual field test?
It depends on the machine, and the technician decides. Guy's and St Thomas' asks you to bring all your glasses, including reading glasses, because the doctor works out whether you should wear them. UH Sussex explains the other side: patients do not wear glasses because frames can block part of the peripheral vision, and the machine has built-in corrective lenses instead. EyeWiki warns that thick lens rims or a wrong head position can make the edge of a result look worse than it is, and that a wrong lens power blurs the lights and changes the readings. So bring your glasses and your prescription, let the technician choose, and tell them if the lights look blurry.
Tips for taking a visual field test
There is no way to study for this test, but a few habits make your result more accurate, which means fewer repeats and a clearer picture of your eyes.
- Keep looking at the centre dot. Moving your eyes towards a light is the commonest error. The test only works if your eye stays still.
- Press for any light you see, however faint. Many of the lights are meant to be at the edge of what anyone can see.
- Do not press when nothing has flashed. Pressing "just in case" or guessing creates false positives, which make a result unreliable. If you are not sure you saw it, wait for the next one.
- Expect to miss many lights. Guy's and St Thomas' says it is normal not to see every light and that there will be periods when you see nothing. That does not mean you are failing.
- Blink as normal. Many people find it easiest to blink just after pressing the button.
- Ask for a pause. If you are uncomfortable, tired or unsure what to do, tell the technician. A brief rest is better than a poor test.
- Sit comfortably before it starts. Adjust your chair so you are not leaning or straining, because moving your head during the test shifts the results.
- Repeat tests are normal. A first test often gives a less accurate result, as explained under "Results" below.
"I hate visual field tests": why they feel so hard
You are not alone, and there are real reasons. You have to stare without moving for several minutes, react to lights you can barely see, and you are never told whether you got one right. A 2025 Cureus study of clinic results found that only about a third of right-eye tests (31%) met a strict reliability standard before patients were given a simple one-page explanation, and 54% afterwards. Fatigue is also real: the Survey of Ophthalmology review reports that sensitivity falls as an uninterrupted test lengthens, especially in glaucoma, and the second eye tested may tire more than the first.
What helps: ask for a short explanation or practice round, rest between eyes, keep your head still, and remember that missing lights is built into the test.
How visual field results are read
Visual field interpretation is a specialist skill. Your surgeon looks at the map, the numbers and the reliability scores together, alongside your pressure readings and optic nerve scans.
Compared with people your age. UH Sussex notes that normal fields depend on age, because sensitivity falls as we get older, so your result is compared with normal results for people of your age.
Reliability scores. Every printout shows how trustworthy the test was: fixation losses (did your eye wander), false positives (did you press when nothing flashed, sometimes called "trigger-happy") and false negatives (did you miss lights you should have seen, which can reflect tiredness or lapses of attention). The 2025 Survey of Ophthalmology review explains that a high false-positive rate is the biggest threat to a reliable result, and that the 15% false-positive limit often quoted may not suit the newest test mode. For the UK driving test, the DVLA says the false-positive score must be no more than 20% for the chart to be considered reliable.
Global figures and maps. Printouts also give summary numbers such as the mean deviation (the average difference from normal for your age), the pattern standard deviation (how uneven the loss is) and the visual field index (a percentage of remaining field), plus colour-coded maps showing where the loss lies.
Abnormal visual field test results: what they can mean
An abnormal result means your sensitivity is lower than expected in one or more areas. It does not on its own give a diagnosis. Possible causes include:
- Glaucoma and other optic nerve damage, usually with a pattern that follows the nerve fibres
- Retinal disease, with blind areas matching the damaged retina
- Brain-related causes such as a stroke, which the UH Sussex leaflet lists among the conditions found by visual field testing
- Eyelid, lens or pupil effects: EyeWiki lists cataract or a small pupil (less light reaching the retina), thick lens rims and wrong refractive correction as common causes of an artificially worse result
- Test factors: tiredness, inattention, learning the test for the first time
Because of this, a single abnormal test is usually repeated. The Survey of Ophthalmology review describes the "learning effect": in one study of glaucoma patients, the mean result improved significantly between the first and second test but not between the second and fifth, and several early tests are needed to establish a reliable baseline. The same review notes that the European Glaucoma Society recommends 3 visual field tests a year for the first 2 years after a glaucoma diagnosis to catch fast progression.
Failed visual field test in one eye
"Failing" one eye usually means one of two things. Either the result in that eye was unreliable (for example many false positives or fixation losses), or it shows a real area of reduced vision in that eye. Your doctor tells the two apart by repeating the test and by comparing it with your optic nerve scan (see our OCT scan page) and eye pressure (tonometry). Do not panic over one test, and do not ignore it either.
How often is it repeated?
UH Sussex says most patients have the test every 6 to 12 months, which research shows is a good interval to detect changes. People newly diagnosed with glaucoma may need it more often, as the European Glaucoma Society advice above shows.
Online visual field tests and the DVLA test
Visual field test online (free)
You will find many free "visual field tests" online. A web page cannot control the distance of your eye from the screen, how still your head is, the room light or whether you are looking at the centre, so it cannot replace a clinic test and cannot diagnose glaucoma. Treat any free online result as a prompt to book a proper examination, not as reassurance.
There is serious research on home testing. A 2020 study in the American Journal of Ophthalmology tested a tablet-based visual field test (Eyecatcher) at home for six months: patients completed 98% of tests, and the results correlated strongly with the clinic machine (r = 0.94). But the home test checked only the central part of the field (about 15 degrees left and right, 9 degrees up and down), and about 9% of single tests were anomalous. The study concluded that tablet testing can supplement clinic monitoring.
The same applies to the Esterman visual field test online: the Esterman is a binocular test that the DVLA requires for driving assessments, and it is done through an optician, not on a web page.
How to pass the DVLA visual field test
You cannot "pass" a visual field test by technique, and you should not try to game it. The test shows whether your real vision meets the driving standard, and the best you can do is give a true, reliable result. For UK car and motorcycle (Group 1) licences, the DVLA requires a binocular field of at least 120 degrees across, extending at least 50 degrees to the left and to the right, with no significant defect within 20 degrees above or below the horizontal. For lorry and bus (Group 2) licences the standard is stricter: at least 160 degrees across, at least 70 degrees each side and 30 degrees above and below. The DVLA says the test must be a binocular Esterman field test.
UK drivers with glaucoma affecting both eyes must tell the DVLA, which may refer you for a free test with a contracted optician. What helps you give a fair result is the same as for any visual field test: keep your eyes on the centre, press only when you see a light, blink naturally, ask for a rest if you need one, and bring the glasses you normally wear. If the result falls short, ask what it showed and whether a repeat test or a review of your glaucoma treatment could help.
How to fail a visual field test
People often search for this, and the honest answer is that nobody should want to. Common causes of an unreliable or unexpectedly poor result are wandering eyes, pressing at random, being tired, wearing the wrong lens power or a frame blocking the edge of vision, and a droopy lid or cataract. All can be reduced with the tips above, and many can be spotted by your technician and surgeon from the reliability scores.
Visual field test price
At Laser Istanbul Clinic a visual field test is part of your pre-operative examination when your surgeon needs it, and is included in the treatment price. If you only want a visual field test, for example for glaucoma monitoring or a second opinion, a standalone examination with visual fields costs {{£ price for a standalone visual field test}}. Hotel and airport transfers are not included and are a separate charge if you would like us to arrange them.
You can also send recent visual field printouts from your own optician or eye doctor for a free initial review before you travel.
Who reads your visual fields
Your results are read by the surgeon who will treat you, not only by the machine. Prof. Dr. Ahmet Satıcı, who leads glaucoma care, reads fields for glaucoma and optic nerve damage. Doç. Dr. Muhammet Derda Özer (Doç. means Associate Professor) reviews fields when the cause may be retinal, an eye inflammation or another condition in his field. Op. Dr. Aysan Bayram reviews fields alongside retinal disease. If anything unexpected shows up, your surgeon explains what it means and what the options are, with your personal interpreter if you wish.
Treatments the visual field test supports
| Treatment or care | How the visual field is used |
|---|---|
| Glaucoma treatment and surgery (laser, MIGS, trabeculectomy, tubes) | Shows how much damage there is, decides how urgent treatment is and tracks whether pressure lowering is working |
| Optic neuropathy and neuro-ophthalmology | Maps the pattern of nerve damage and follows recovery or progression |
| Retinal disease care | Matches blind areas to areas of retinal damage |
| Eyelid surgery for drooping lids | Documents how much the lid blocks your upper vision |
Other tests in your eye examination
The visual field test is usually done alongside other tests, each answering a different question:
- Tonometry (eye pressure measurement): measures the pressure inside the eye, a key treatable factor in glaucoma (/en/eye-tests-diagnostics/tonometry/)
- OCT scan (optical coherence tomography): shows the optic nerve and retinal layers in detail (/en/eye-tests-diagnostics/oct-scan/)
- VEP & ERG electrophysiology tests: measure the electrical responses of the retina and visual pathway (/en/eye-tests-diagnostics/vep-erg-tests/)
- FFA (fundus fluorescein angiography): imaging of the blood vessels at the back of the eye (/en/eye-tests-diagnostics/fluorescein-angiography/)
- Eye ultrasound (B-scan): imaging when the inside of the eye cannot be seen directly (/en/eye-tests-diagnostics/eye-ultrasound/)
- Corneal topography: maps the shape of the cornea before laser and lens surgery (/en/eye-tests-diagnostics/corneal-topography/)
Visual field test: frequently asked questions
A visual field test, or perimetry, measures your central and side vision. You look at a fixed point and press a button whenever you see a flash of light, and the machine maps where your vision is reduced or missing. It is used to diagnose and monitor glaucoma and other conditions affecting the retina, the optic nerve and the brain's visual pathways.
The Humphrey test usually takes 5 to 10 minutes per eye according to Guy's and St Thomas' NHS Foundation Trust, and 3 to 5 minutes in some clinics. A Goldmann test can take up to 30 minutes per eye. Allow extra time for the explanation and any repeat test.
Bring them, but the technician decides. Some clinics ask you to wear your glasses; others use built-in lenses in the machine because frames can block peripheral vision. A wrong lens power can blur the lights, so say if they look unclear.
That is normal. The machine deliberately shows very faint lights, so everyone misses some. Keep looking at the centre and press only when you see a flash. Do not worry about the ones you miss.
Keep your eyes on the centre dot, press for any light you see, never guess, blink naturally, sit comfortably and ask for a break if you are tired or unsure. Repeat tests are common, and your second test is often better than the first.
Many people do. Ask for an explanation or practice round, rest between eyes and tell the technician if you are struggling. A short rest gives a more reliable result than pushing on while tired.
You cannot pass it by technique; it measures whether your vision meets the driving standard. Give an honest result by keeping your eyes on the centre and pressing only when you see a light. For a UK car licence, the DVLA requires a binocular field of at least 120 degrees with no significant defect within 20 degrees above or below the horizontal. The test used is a binocular Esterman.
They mean some areas of your vision are less sensitive than expected for your age. Causes include glaucoma, optic nerve disease, retinal disease, a stroke, or test factors such as tiredness, a droopy lid or the wrong lens. Your doctor usually repeats the test and compares it with scans before deciding.
Either the result in that eye was unreliable, or it shows a real area of reduced vision. Doctors repeat the test and check your optic nerve and eye pressure to tell which. It needs follow-up, not panic.
Free online tests cannot control distance, lighting or eye position, so they cannot diagnose glaucoma or replace a clinic test. Tablet tests for home monitoring have been studied, but they supplement clinic visits rather than replace them.
It is included in the treatment price at Laser Istanbul Clinic when your surgeon needs it as part of your examination. A standalone visual field examination costs {{£ price for a standalone visual field test}}. Hotel and transfers are extra.
Most patients with glaucoma are tested every 6 to 12 months, and more often in the first two years after diagnosis. The European Glaucoma Society recommends 3 tests a year for the first 2 years to spot fast progression.
Sources for the facts on this page
- Guy's and St Thomas' NHS Foundation Trust, Visual field eye test: assesses central and peripheral vision; used in glaucoma and neurology clinics; Humphrey test 5-10 minutes per eye, Goldmann up to 30 minutes per eye; bring all glasses including reading glasses; normal not to see every light; blink naturally. https://www.guysandstthomas.nhs.uk/health-information/visual-field-eye-test
- University Hospitals Sussex NHS Foundation Trust, Visual field testing (patient leaflet 2249.1, 2025): reasons for the test (glaucoma, stroke, drooping lids, neurological problems); 3-5 minutes per eye; no glasses because frames block peripheral vision, built-in lenses; results compared with age-matched normals; test every 6-12 months; driving with field loss. https://www.uhsussex.nhs.uk/resources/visual-fields-testing-3/
- Tan JCK, Yohannan J, Ramulu PY, Kalloniatis M, Crabb DP, Crowston J, Phu J. Visual field testing in glaucoma using the Swedish Interactive Thresholding Algorithm (SITA). Surv Ophthalmol 2025;70(1):141-152 (doi 10.1016/j.survophthal.2024.09.005): Humphrey the most common instrument; 24-2 and 10-2 grids; SITA time savings; reliability indices and false-positive cut-off; learning effect; fatigue; EGS 3 tests/year for 2 years. https://openaccess.city.ac.uk/id/eprint/33968/
- Suresh B, Kathiramalai S, Kaneshayogan H. Improving Visual Field Testing Reliability by Using an Educational Patient Leaflet. Cureus 2025: reliability indices; strict reliability 31% to 54% (right eye) after leaflet; learning and fatigue effects. https://pmc.ncbi.nlm.nih.gov/articles/PMC12662638/
- Broadway DC. Visual field testing for glaucoma: a practical guide. Community Eye Health 2012: static vs kinetic perimetry; glaucoma defect patterns (arcuate, nasal step, paracentral); repeat testing vital. https://pmc.ncbi.nlm.nih.gov/articles/PMC3588129/
- EyeWiki (AAO), Standard Automated Perimetry: artifacts (lens rim, cataract and small pupil, wrong refractive correction, inattention); 24-2 tests 54 points. https://eyewiki.org/Standard_Automated_Perimetry
- EyeWiki (AAO), Blepharoptosis: visual field requested to show the effect of ptosis on peripheral vision. https://eyewiki.org/Blepharoptosis
- National Eye Institute, Glaucoma: group of diseases damaging the optic nerve; side vision lost first; half of people do not know; dilated exam with visual field test; treatment stops damage getting worse but does not undo it. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucoma
- GOV.UK (DVLA), Visual disorders: assessing fitness to drive (updated 26 September 2025): Group 1 binocular field standard (120 degrees horizontal; 50 degrees left and right; no significant defect within 20 degrees above or below horizontal); Group 2 standard (160 degrees; 70 degrees each side; 30 degrees above and below); binocular Esterman required; false-positive score no more than 20%. https://www.gov.uk/guidance/visual-disorders-assessing-fitness-to-drive
- GOV.UK, Glaucoma and driving: tell DVLA if glaucoma affects both eyes; DVLA may refer for a free test with a contracted optician. https://www.gov.uk/glaucoma-and-driving
- Jones PR, Campbell P, Callaghan T, et al. Glaucoma Home Monitoring Using a Tablet-Based Visual Field Test (Eyecatcher): An Assessment of Accuracy and Adherence Over 6 Months. Am J Ophthalmol 2020: 98% of home tests completed; r = 0.94 with clinic; paracentral field only; about 9% anomalous tests. https://pmc.ncbi.nlm.nih.gov/articles/PMC7462567
Already have visual field results? Let a surgeon look at them, free
Upload your visual field printouts, OCT scans and prescription. Prof. Dr. Satıcı, Doç. Dr. Özer or Op. Dr. Bayram will tell you what they show and which treatments may suit you, with no obligation. If your sight has changed suddenly, see an eye emergency service near you first.
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Prof. Dr. Ahmet Satıcı
Doç. Dr. Muhammet Derda Özer
Op. Dr. Aysan Bayram