Author: Dr Val Phua
Estimated reading time: 13–15 minutes
What Is a Visual Field Test?
A visual field test measures how much of the surrounding world you can see while looking straight ahead.
Your visual field includes:
- Central vision used for reading and recognising faces
- Side, or peripheral, vision
- Vision above and below fixation
- Sensitivity to objects of different brightness
- The ability to detect small or faint targets
Most visual-field tests examine one eye at a time. The patient looks steadily at a central target while lights appear in different locations.
The test records:
- Which lights were seen
- Which lights were missed
- How dim a light could be detected at each location
- Whether any blind spots form a recognisable pattern
- Whether the field has changed compared with earlier tests
Visual-field testing is particularly important for glaucoma because central reading vision may remain clear while peripheral nerve fibres are already damaged. It is also used for neurological disease, retinal disorders, eyelid abnormalities, medication monitoring and driving-fitness assessments.
What Is the Difference Between Visual Acuity and Visual Field?
Visual acuity measures how clearly you can see a small, high-contrast target directly in front of you.
It is commonly recorded as:
- 6/6
- 6/9
- 20/20
- 20/30
A visual-field test measures how widely and sensitively you can see around the central point.
A person may have:
- Excellent 6/6 central vision
- Significant peripheral visual-field loss
- Difficulty detecting hazards from the side
- Problems driving or navigating despite reading the eye chart well
This is why a visual-acuity test alone cannot exclude glaucoma or determine whether the field of vision is adequate for a particular task.
What Does a Normal Visual Field Look Like?
A normal field is not equally sensitive everywhere.
Vision is most sensitive near the centre and becomes less sensitive farther into the periphery.
Each eye also has a natural blind spot where the optic nerve leaves the retina. There are no light-detecting cells at this location.
A normal field therefore includes:
- High central sensitivity
- Gradually lower peripheral sensitivity
- A physiological blind spot
- Predictable changes according to age
Visual-field machines compare the patient’s responses with a reference database of people of a similar age.
A missed light is not automatically abnormal. The interpretation depends on:
- How bright the light was
- Where it appeared
- Whether nearby locations were also affected
- Whether the pattern matches the optic nerve, retina or visual pathway
- Whether the result can be repeated
Why Are Visual Field Tests Performed?
Visual-field tests may be used to:
- Detect glaucoma
- Measure the severity of glaucoma
- Monitor glaucoma progression
- Investigate unexplained visual loss
- Assess optic-nerve disease
- Detect visual-pathway problems from the eye to the brain
- Assess pituitary or other intracranial lesions
- Evaluate retinal disease
- Document visual effects of drooping eyelids
- Assess possible functional or non-organic visual loss
- Evaluate fitness to drive
- Monitor medication-associated retinal toxicity in selected cases
The testing pattern and technique should match the suspected condition.
A glaucoma-monitoring test is not necessarily the same as a neurological or driving-field assessment.
How Does Glaucoma Affect the Visual Field?
Glaucoma damages retinal ganglion cells and the optic-nerve fibres carrying visual information to the brain.
Early defects may include:
- A nasal step
- A paracentral defect
- An arcuate scotoma
- A cluster of reduced sensitivity above or below fixation
- Localised loss corresponding to a retinal nerve-fibre defect
As glaucoma progresses, defects may:
- Become deeper
- Increase in area
- Join with other blind spots
- Cause peripheral constriction
- Approach central fixation
- Leave only a small central or temporal island in advanced disease
A patient may not notice early or moderate defects because the other eye compensates and the brain fills in missing information. Standard automated perimetry remains the main functional test used to assess glaucomatous visual loss.
Does a Normal Visual Field Exclude Glaucoma?
No.
Structural glaucoma damage may be visible on:
- Optic-nerve examination
- Optic-disc photography
- Retinal nerve-fibre layer OCT
- Macular ganglion-cell analysis
before a clear defect is detected on a standard visual-field test.
This is sometimes called pre-perimetric glaucoma.
A normal field also does not exclude:
- Very early disease
- A defect located between the tested points
- Central loss inadequately sampled by the selected test pattern
- An unreliable result
- Disease that is visible only when compared over time
Visual fields and OCT provide complementary information. Neither should automatically replace the other.
What Is Standard Automated Perimetry?
Standard automated perimetry is the most commonly used quantitative visual-field test for glaucoma.
A computer-controlled machine presents small white lights against a uniformly illuminated background.
The patient:
- Covers one eye.
- Places the chin and forehead against the machine.
- Looks steadily at a central target.
- Presses a button whenever a light is seen.
- Avoids looking directly towards the appearing lights.
- Repeats the process with the other eye.
The machine varies the brightness of the lights to estimate the threshold sensitivity at each tested location.
Threshold sensitivity is the dimmest light that can be detected reliably at that point.
Guidelines recommend standard automated perimetry for diagnosing and monitoring chronic open-angle glaucoma and repeating the test when necessary to establish severity or confirm change.
Is the Visual Field Test Painful?
No.
The test is non-invasive and should not cause pain.
Some patients find it:
- Tiring
- Repetitive
- Frustrating
- Difficult to concentrate on
- Uncomfortable because of posture or dry eye
The technician can usually pause the test when necessary.
The machine is designed to present some lights that are too dim to see. Missing lights is expected and does not mean that the patient has failed.
How Long Does a Visual Field Test Take?
The duration depends on:
- Test pattern
- Testing algorithm
- Disease severity
- Patient response speed
- Reliability
- Whether one or both eyes are tested
A routine modern glaucoma threshold test may take only a few minutes per eye.
Older or more detailed strategies may take longer.
SITA Faster testing was designed to shorten examination time compared with SITA Standard and SITA Fast while preserving clinically comparable results. Official manufacturer information reports that SITA Faster 24-2 is approximately 50% faster than SITA Standard, although actual times vary between patients.
What Is SITA?
SITA stands for Swedish Interactive Thresholding Algorithm.
It is a family of algorithms used by Humphrey visual-field machines to estimate retinal sensitivity efficiently.
Common versions include:
- SITA Standard
- SITA Fast
- SITA Faster
They differ mainly in testing speed and the way responses are sampled and checked.
A faster test may reduce fatigue, but the selected strategy should remain appropriate for:
- The disease
- The patient
- Previous baseline tests
- Progression analysis
Results obtained with different strategies may not always be interpreted as identical without considering the machine and software used.
What Do 24-2, 24-2C, 30-2 and 10-2 Mean?
These numbers describe different patterns of test locations.
24-2
The 24-2 test examines the central approximately 24 degrees of vision, with points spaced six degrees apart.
It is widely used for:
- Glaucoma detection
- Routine glaucoma monitoring
- Optic-nerve disease
It provides broad coverage while keeping the test reasonably short.
24-2C
The 24-2C pattern is based on the 24-2 grid but adds ten locations in the central region where glaucomatous defects commonly occur.
It aims to improve central sampling without requiring a separate full 10-2 test for every patient.
A 2025 systematic review concluded that 24-2C testing was faster than 24-2 Standard and 10-2 strategies in the reviewed studies and detected more central visual-field defects than the conventional 24-2 pattern.
30-2
The 30-2 test examines a slightly wider central area than the 24-2.
It is commonly used for:
- Neurological field assessment
- Optic neuropathy
- Pituitary or chiasmal disease
- Selected glaucoma cases
It takes longer because it tests more locations.
10-2
The 10-2 test examines the central ten degrees using points spaced approximately two degrees apart.
It provides much denser central testing.
It may be particularly useful when:
- Glaucoma threatens fixation
- A paracentral defect is suspected
- Macular ganglion-cell loss is present
- The 24-2 appears normal despite central structural damage
- Advanced disease leaves a small central field
- Toxic maculopathy is being assessed using an appropriate strategy
Studies have shown that conventional 24-2 testing may miss some central defects detected by 10-2 testing. The 10-2 test should therefore be considered when the clinical findings suggest central involvement.
Is 10-2 Always Better Than 24-2?
No.
The 10-2 examines the central field in much greater detail but does not adequately assess the wider peripheral area covered by a 24-2 or 30-2 test.
A patient may require:
- 24-2 alone
- 24-2C alone
- 24-2 plus 10-2
- Different tests at alternating visits
The choice depends on:
- Disease pattern
- Stage
- OCT findings
- Location of visual-field loss
- Risk to central fixation
- Available testing time
Research suggests that 10-2 testing may modestly shorten the time required to detect central progression in eyes already known to have early central abnormalities.
What Is Kinetic Perimetry?
Kinetic perimetry uses a moving target.
The examiner moves a light from an area where it cannot be seen towards an area where it becomes visible.
The patient indicates when the light is first detected.
The responses are used to draw boundaries called isopters, representing areas of equal visual sensitivity.
Kinetic testing may be useful for:
- Very advanced field loss
- Neurological disease
- Retinal dystrophy
- Children
- Patients unable to perform reliable automated threshold testing
- Mapping very peripheral vision
- Disability or functional assessments
Goldmann perimetry is the traditional example, although newer automated machines can also perform kinetic testing.
What Is Confrontation Visual-Field Testing?
Confrontation testing is a quick clinical screening method.
The examiner compares the patient’s field with their own by presenting fingers or targets in different areas.
It can detect:
- Large field defects
- Hemianopia
- Severe peripheral loss
- Gross asymmetry
It is not sensitive enough to exclude early glaucoma or small defects.
A normal confrontation field does not replace automated perimetry.
What Is Frequency-Doubling Perimetry?
Frequency-doubling technology presents flickering striped patterns that create an optical frequency-doubling illusion.
It has been used as:
- A glaucoma-screening test
- A functional assessment in patients unable to complete longer threshold tests
- A supplementary test in selected settings
An abnormal screening result generally requires confirmation with a comprehensive eye examination and standard automated perimetry.
What Is an Esterman Visual Field Test?
The Esterman test is a suprathreshold visual-field assessment designed to evaluate functional binocular vision.
Unlike routine glaucoma fields:
- Both eyes are generally tested together for the binocular version.
- Targets are presented across a wide field.
- The result focuses on whether targets were detected rather than measuring detailed threshold sensitivity.
It may be used in selected assessments of:
- Driving fitness
- Functional visual disability
- Binocular visual capacity
The Esterman test does not replace monocular glaucoma fields because it can hide damage in one eye when the other eye compensates.
Research confirms that binocular field loss can affect driving response and that the Esterman test has recognised use in driving-related assessments, although licensing requirements vary by jurisdiction.
What Is a Monocular Visual Field?
A monocular field tests one eye while the other is covered.
This is necessary for diagnosing and monitoring disease because it identifies:
- Which eye is affected
- The location of the defect
- Asymmetry between the eyes
- Progression in each eye separately
Routine Humphrey 24-2, 24-2C and 10-2 tests are usually monocular.
What Is a Binocular Visual Field?
A binocular field measures the combined area visible with both eyes open.
The two monocular fields overlap substantially.
A binocular test reflects everyday functional vision better for tasks such as driving but may conceal severe loss in one eye.
Monocular and binocular fields answer different clinical questions.
How Should I Prepare for a Visual Field Test?
Before testing:
- Bring your current spectacles.
- Bring an updated medication list.
- Use glaucoma drops as normally prescribed unless instructed otherwise.
- Tell the technician if you are tired or unwell.
- Mention neck, back or shoulder problems.
- Remove contact lenses if advised.
- Inform the clinic if you have significant dry eye.
- Use the toilet before a long test.
- Avoid rushing into the test when very breathless or distressed.
Sleep deprivation, fatigue and poor concentration may make the test more variable.
You do not need to memorise a pattern or practise clicking rapidly beforehand.
Should I Wear My Glasses During the Test?
The machine may require an appropriate trial lens for the tested distance.
The correction depends on:
- Age
- Distance prescription
- Test pattern
- Instrument
- Working distance
The patient may not wear their ordinary spectacles inside the bowl because:
- The frame can block peripheral targets.
- The lenses may sit at the wrong distance.
- Progressive or bifocal zones may distort the test.
The technician will provide the required correction.
How Can I Perform the Test More Reliably?
Keep Looking at the Central Target
Do not chase the lights with your eyes.
The machine is testing what you can see away from fixation.
Looking towards each light changes the part of the retina being tested and may create misleading results.
Press Only When You Actually See a Light
Some lights will be extremely faint.
It is normal not to see every presentation.
Avoid pressing because:
- You think a light should appear
- You hear a machine sound
- You are worried about missing one
- You want the test to finish faster
Do Not Wait for a Perfectly Bright Light
Press when you believe you saw a light, even if it was:
- Dim
- Brief
- Small
- Uncertain but genuinely visible
The test repeatedly checks the threshold and does not expect absolute certainty.
Blink Normally
Blinking keeps the corneal surface clear.
You may blink at any time.
Try not to hold the eye open continuously, as dryness can reduce vision and make lights harder to detect.
Ask for a Pause
The test can usually be paused if you need to:
- Blink repeatedly
- Stretch
- Reposition
- Rest
- Ask a question
A short pause is preferable to continuing with poor concentration.
Keep Breathing
Relax your jaw, shoulders and forehead.
The test is not a reaction-speed competition.
Should I Click When I Am Not Sure?
Press the button when you believe you genuinely saw something.
Do not click for every possible flicker or sensation.
A useful approach is:
- Seen or reasonably perceived: press
- Only expected or imagined: do not press
The algorithm presents stimuli repeatedly and can tolerate occasional uncertainty.
Why Does the Test Sometimes Seem to Show No Lights?
The machine intentionally presents lights near and below your detection threshold.
Periods without visible targets are normal.
Do not assume:
- The machine has stopped
- You are performing badly
- You need to click to restart it
Remain focused on the central target.
Why Is the First Visual Field Often Less Reliable?
Visual-field testing has a learning effect.
New patients must learn:
- How faint the lights can be
- How to maintain fixation
- When to press
- How quickly the test proceeds
- How to ignore machine noise
- How to remain relaxed
Performance often improves after one or more tests.
Studies have found measurable improvements in reliability and global indices with repeat testing, particularly among inexperienced patients.
An abnormal first test should therefore be interpreted cautiously when it does not match the optic nerve or OCT.
Why Must an Abnormal Visual Field Be Repeated?
A defect may be caused by:
- True disease
- Fatigue
- Poor fixation
- Excessive button pressing
- Inattention
- Dry eye
- Incorrect trial lens
- Lens-rim obstruction
- Drooping eyelid
- Cataract
- Small pupil
- Poor positioning
- Learning effect
Glaucoma diagnosis and progression should generally rely on a reproducible pattern rather than one isolated abnormal field.
NICE guidance specifically recommends repeating visual-field testing when clinically necessary to establish diagnosis or severity.
What Are Reliability Indices?
Visual-field reports contain indicators intended to help assess test quality.
Common indices include:
- Fixation losses
- False-positive responses
- False-negative responses
- Gaze tracking
- Test duration
- Response patterns
These values should not be used as rigid pass-or-fail criteria.
The clinician should assess the whole test, including:
- Whether the defect is anatomically plausible
- Whether it matches OCT or optic-disc findings
- Whether the same pattern occurred previously
- Whether the patient appeared attentive
- Whether artefacts are present
Research shows that traditional reliability indices have limitations and should be interpreted in context.
What Are Fixation Losses?
Fixation losses estimate how often the patient responded to a target presented in the physiological blind spot or appeared to move away from central fixation.
A high value may occur because:
- The patient looked around
- The blind spot was mapped inaccurately
- Head position changed
- The eye drifted
- The machine recorded pseudo-fixation losses
Fixation-loss percentages can sometimes look poor even when the field is clinically usable.
Modern gaze-tracking displays may provide additional information about eye movement during testing.
What Are False Positives?
False positives occur when the patient presses the button even though no valid visible stimulus was presented.
Possible reasons include:
- Anticipating the lights
- Clicking to machine sounds
- Trying too hard
- Anxiety
- Pressing repeatedly
- Misunderstanding the task
A high false-positive rate can make the field look artificially better than it really is.
Possible clues include:
- Unusually high sensitivity
- Excessively white areas
- An abnormal “trigger-happy” pattern
- Implausibly good responses despite known disease
False positives are often among the most clinically important reliability problems, although no single percentage should be interpreted without reviewing the entire field.
What Are False Negatives?
False negatives occur when the patient fails to respond to a brighter light at a location where a dimmer light was previously seen.
They may reflect:
- Fatigue
- Inattention
- Fluctuating response
- Advanced glaucoma
- Local retinal sensitivity variability
High false-negative rates do not always mean the patient performed poorly.
They are more common in damaged visual fields because diseased locations naturally produce less consistent responses.
The result should be interpreted alongside disease severity and the response pattern rather than rejected automatically.
What Is Gaze Tracking?
Gaze tracking records eye movement during the test.
It can help identify:
- Looking away from the central target
- Sudden eye movements
- Blinks
- Poor head position
- Periods of lost tracking
A few gaze movements are common.
The pattern is more useful than expecting a perfectly flat tracing throughout the test.
What Is the Grayscale Plot?
The grayscale plot provides a visual map of sensitivity.
Darker areas indicate lower sensitivity.
It is easy to understand visually but should not be used alone because:
- Small numerical changes can look dramatic.
- Cataract may darken the whole field.
- Scaling can exaggerate differences.
- Artefacts may resemble disease.
The numerical and probability plots provide more precise information.
What Are Threshold Values?
Threshold values are expressed in decibels, or dB.
A higher number indicates greater sensitivity to dim light.
A lower number indicates reduced sensitivity.
Decibels are logarithmic rather than linear. A change of several decibels therefore represents a substantial change in light sensitivity.
Sensitivity normally decreases with:
- Increasing age
- Greater distance from fixation
- Cataract or media opacity
- Retinal or optic-nerve disease
What Is the Total Deviation Plot?
The total deviation plot compares the patient’s measured sensitivity at each point with the expected sensitivity for a healthy person of similar age.
It shows areas that are:
- Better than expected
- Within the expected range
- Reduced relative to normal
Diffuse conditions such as cataract may make much of the total-deviation field appear depressed.
What Is the Pattern Deviation Plot?
The pattern deviation plot adjusts for a generalised reduction in sensitivity and highlights localised defects.
It is useful for detecting focal loss such as:
- Glaucomatous arcuate defects
- Nasal steps
- Localised scotomas
However, the adjustment can become less reliable in very advanced disease or when generalised loss is severe.
The clinician interprets total and pattern deviation together.
What Is Mean Deviation?
Mean deviation, or MD, summarises the overall difference between the patient’s field and the age-matched normal field.
It is expressed in decibels.
In general:
- A value near zero suggests an approximately normal overall field.
- A more negative value indicates greater generalised loss.
MD may be affected by:
- Glaucoma
- Cataract
- Small pupils
- Defocus
- Retinal disease
- Poor test performance
It is useful for staging and progression but should not replace point-by-point analysis.
What Is Pattern Standard Deviation?
Pattern standard deviation, or PSD, reflects how irregular the field is compared with the expected smooth shape.
PSD may increase when localised defects develop.
It may become less useful in very advanced disease when most of the field is severely depressed.
A high PSD does not diagnose glaucoma by itself because localised retinal, optic-nerve or artefactual defects can also increase it.
What Is the Visual Field Index?
The Visual Field Index, or VFI, is a percentage intended to summarise visual-field function.
A value close to 100% represents relatively preserved function, while lower values indicate greater loss.
VFI gives greater weighting to central locations because central vision is particularly important for daily function.
It may be used in trend analysis to estimate:
- Rate of field loss
- Whether progression is statistically significant
- A projected future course if the same rate continued
The projected course is not a guarantee because progression and treatment may change over time. VFI correlates strongly with MD but has its own limitations, particularly in early or advanced disease.
What Is the Glaucoma Hemifield Test?
The Glaucoma Hemifield Test compares corresponding areas above and below the horizontal midline.
Glaucoma commonly affects one side of the horizontal meridian more than the matching area on the other side.
Possible classifications include:
- Within normal limits
- Borderline
- Outside normal limits
- General reduction of sensitivity
- Abnormally high sensitivity
The result is a screening interpretation and does not confirm glaucoma by itself.
What Does “Outside Normal Limits” Mean?
It means the test result differs statistically from the reference database according to the machine’s criteria.
It does not automatically mean:
- Definite glaucoma
- Permanent damage
- Rapid deterioration
- Legal visual disability
The result must be compared with:
- Optic-nerve appearance
- OCT
- Previous fields
- Reliability
- Cataract status
- Retinal findings
- Neurological history
What Are Common Glaucoma Visual-Field Patterns?
Nasal Step
A defect close to the nasal horizontal midline.
It reflects the arrangement of retinal nerve fibres and may be an early glaucomatous pattern.
Paracentral Scotoma
A defect close to central fixation.
It may significantly affect reading or detailed vision even when overall MD remains relatively mild.
A 10-2 or 24-2C field may be useful.
Arcuate Scotoma
A curved defect following the retinal nerve-fibre pathway from the blind spot towards the nasal field.
Temporal Wedge
A less common defect caused by damage to nasal retinal fibres.
Peripheral Constriction
The remaining visual field becomes progressively narrower.
Central or Temporal Island
Advanced glaucoma may leave only a small area of usable vision.
Can a Visual Field Show a Stroke or Brain Problem?
Yes.
The visual pathway extends from both eyes through the optic nerves, optic chiasm, optic tracts and brain.
Neurological patterns may include:
- Bitemporal hemianopia
- Homonymous hemianopia
- Quadrantanopia
- Central or cecocentral scotomas
- Vertical-meridian defects
A defect that respects the vertical midline may suggest a neurological rather than typical glaucomatous pattern.
Possible causes include:
- Stroke
- Pituitary tumour
- Brain tumour
- Optic-nerve compression
- Multiple sclerosis
- Trauma
- Other neurological disease
Unexpected neurological field patterns may require neuroimaging or specialist assessment.
What Is Bitemporal Hemianopia?
Bitemporal hemianopia is loss of the outer half of the visual field in both eyes.
It may indicate compression at the optic chiasm, where fibres from the two optic nerves cross.
A pituitary lesion is one possible cause, but other conditions can also produce this pattern.
The visual-field finding must be correlated with:
- Symptoms
- Pupil reactions
- Colour vision
- Optic-nerve appearance
- Neuroimaging
What Is Homonymous Hemianopia?
Homonymous hemianopia is loss of the same side of the visual field in both eyes.
For example, a right homonymous hemianopia affects the right visual field of each eye.
It usually indicates damage behind the optic chiasm, such as:
- Stroke
- Brain tumour
- Trauma
- Neurological inflammation
A sudden field defect may require urgent medical assessment.
Can Retinal Disease Affect the Visual Field?
Yes.
Visual-field loss may occur with:
- Retinal detachment
- Retinitis pigmentosa
- Retinal vascular occlusion
- Macular disease
- Laser scars
- Retinal toxicity
- Chorioretinal inflammation
The pattern should be interpreted with retinal examination and imaging.
Can Cataract Affect the Visual Field?
Yes.
Cataract can cause a generalised reduction in sensitivity.
The field may appear:
- Darker overall
- More depressed on total deviation
- Worse in mean deviation
- Less reliable because of reduced contrast
Localised cataract or lens opacity can sometimes create uneven defects.
Visual-field results may improve after cataract surgery even though true glaucomatous nerve damage remains.
Can Dry Eye Affect the Test?
Yes.
An irregular or drying tear film may cause:
- Fluctuating blur
- Reduced contrast
- Missed lights
- Variable responses
Blinking normally and using prescribed lubrication before testing may help.
If artificial tears are required, the technician can advise on timing so that vision is not blurred by a thick gel or ointment.
Can a Drooping Eyelid Affect the Field?
Yes.
A significant drooping upper eyelid may block superior targets.
The technician may tape the eyelid upward when appropriate.
Visual-field testing may also be used to document functional impairment before ptosis or excess-eyelid-skin surgery.
Can the Nose or Brow Block the Field?
Facial anatomy, head position and poor alignment may create apparent peripheral defects.
Possible artefacts include:
- Brow obstruction
- Nose-related field loss
- Deep-set eyes
- Incorrect chin position
- Head tilt
The technician should reposition the patient when necessary.
What Is a Trial-Lens Artefact?
A trial lens or its rim can block peripheral test points if:
- It is positioned too far from the eye.
- The lens holder is not centred.
- The prescription lens is too small.
- The patient moves backwards.
This may create a curved peripheral defect that does not represent disease.
What Is a Cloverleaf Field?
A cloverleaf pattern can occur when the patient responds well at the beginning but stops concentrating as the test progresses.
The machine may establish relatively normal sensitivity at a few initial points in each quadrant, while surrounding points appear markedly reduced.
It may be associated with:
- Fatigue
- Poor attention
- Confusion
- Discomfort
- Cognitive impairment
- Desire to finish quickly
The field may need to be repeated using improved instructions, rest breaks or a shorter strategy.
Can Face Masks Affect the Test?
A poorly fitted mask may:
- Fog the trial lens
- Cause fluctuating blur
- Increase fixation losses
- Increase false-positive responses
- Encourage head movement
Research during the COVID-19 period found that poorly fitting masks could reduce standard automated perimetry reliability.
The mask should be secured to prevent fogging when its use is required.
Can Anxiety Affect the Test?
Yes.
Anxious patients may:
- Press too often
- Hold their breath
- move their head
- Chase lights
- Become fatigued
- Misinterpret machine noises
Clear instructions and reassurance improve performance.
The test is not an examination that the patient passes or fails.
Can Children Perform Visual Field Tests?
Many children can complete automated fields, but success depends on:
- Age
- Attention
- Understanding
- Motivation
- Disease
- Test duration
A shorter strategy, kinetic field or specialised paediatric approach may be used.
Several practice attempts may be necessary.
Can Older Adults Perform the Test Reliably?
Yes.
Age alone does not prevent useful testing.
Adjustments may include:
- Comfortable positioning
- Shorter algorithms
- Clear instructions
- Rest breaks
- Proper near correction
- Management of dry eye
- Assistance for hearing or mobility limitations
Cognitive impairment or severe fatigue may limit reliability.
What Happens If I Cannot Complete the Test?
The test may be:
- Paused
- Repeated another day
- Shortened
- Changed to a different strategy
- Replaced with kinetic testing
- Supplemented with OCT or other assessments
A poor test does not mean the patient has failed.
The clinical team should choose the most useful available method.
Why Are Several Baseline Fields Needed?
Visual-field measurements naturally fluctuate.
A single test cannot reliably establish a personal rate of progression.
Several tests help the clinician:
- Confirm the defect
- Estimate normal test-to-test variability
- Establish a baseline
- Detect rapid progression earlier
- Separate learning effects from disease
More frequent testing early after diagnosis may help identify patients whose fields are deteriorating quickly.
What Is Visual-Field Progression?
Progression means that visual function has worsened beyond expected test variability.
It may be assessed using:
- Event analysis
- Trend analysis
- Point-by-point comparison
- Mean deviation slope
- VFI slope
- Comparison of defect depth and area
Event Analysis
Event analysis compares follow-up results with baseline tests and identifies locations that have worsened beyond expected variability.
Trend Analysis
Trend analysis estimates the rate of change over time.
For example, it may calculate the yearly change in:
- MD
- VFI
- Individual test locations
A statistically significant slope is interpreted alongside age, life expectancy, disease severity and treatment.
What Is Guided Progression Analysis?
Guided Progression Analysis is software that compares serial visual fields with baseline tests.
It can identify:
- Possible progression
- Likely progression
- Rate of VFI change
- Locations repeatedly showing deterioration
The result depends on:
- Reliable baseline tests
- Compatible testing strategies
- Sufficient follow-up examinations
- Consistent testing conditions
Software does not replace clinical judgement.
How Often Should Visual Fields Be Repeated?
The interval depends on:
- Diagnosis
- Disease severity
- Rate of progression
- Reliability
- Treatment changes
- Risk to central vision
- Age and life expectancy
A stable low-risk glaucoma suspect may be tested less often.
More frequent testing may be needed when:
- Glaucoma is newly diagnosed
- Baseline fields are being established
- Disease is advanced
- Progression is suspected
- Pressure remains above target
- Treatment has changed
- The defect threatens fixation
- Previous results were unreliable
Guidelines recommend repeating fields according to clinical risk rather than using one fixed interval for every patient.
Why Did My Field Improve?
Possible reasons include:
- Learning effect
- Better concentration
- Improved correction
- Less dry eye
- Cataract surgery
- Better eyelid position
- Reduced fatigue
- Ordinary test variability
True glaucomatous nerve loss does not usually recover.
An improved field therefore does not necessarily mean that glaucoma damage has reversed.
Why Did My Field Suddenly Become Worse?
Possible explanations include:
- True disease progression
- Cataract
- Incorrect trial lens
- Dry eye
- Fatigue
- Poor fixation
- Excessive false-positive or false-negative responses
- Drooping eyelid
- Small pupil
- Neurological disease
- Retinal disease
- Learning or attention variation
An unexpected result may need repeating before major treatment decisions are made, unless other findings confirm urgent deterioration.
Can OCT Replace Visual-Field Testing?
No.
OCT measures structure.
Visual-field testing measures function.
The two tests may disagree because:
- Structural damage may appear before measurable field loss.
- Functional loss may progress after OCT measurements reach a floor.
- OCT may contain segmentation artefacts.
- High myopia may distort the scan.
- Visual fields may be unreliable.
Both are valuable for long-term glaucoma monitoring.
Can Visual Fields Replace OCT?
No.
A field may appear normal despite early structural loss.
OCT can help identify:
- Retinal nerve-fibre thinning
- Macular ganglion-cell loss
- Progression that has not yet produced a clear field defect
The tests should be interpreted together with optic-nerve examination and pressure history.
Can I Drive If My Visual Field Is Abnormal?
It depends on:
- Which eye is affected
- The combined binocular field
- Location and depth of loss
- Central vision
- Local licensing standards
- Other eye conditions
- Functional ability
A person may have severe loss in one eye but a relatively preserved binocular field because the other eye compensates.
Another patient may have moderate loss in both eyes that overlaps and creates significant binocular impairment.
A specific binocular driving field, often an Esterman-type test, may be requested.
Passing a driving field does not mean that glaucoma is mild, and failing a monocular glaucoma field does not automatically mean the patient cannot drive.
Can I Memorise the Test and Improve My Result?
No.
The location, timing and brightness of the lights vary.
Familiarity may improve technique and reduce anxiety, but it cannot reliably conceal a real visual-field defect.
Trying to anticipate lights usually increases false-positive responses and reduces reliability.
Frequently Asked Questions
Why are some lights bright and others very dim?
The machine changes brightness to determine the minimum sensitivity at each location.
Am I supposed to see every light?
No.
Some lights are intentionally below your visual threshold.
Should I look towards a light when I notice it?
No.
Keep looking at the central target and press the button.
Can I blink during the test?
Yes.
Blink normally.
Can I pause the test?
Usually, yes. Tell the technician when you need a break.
Why does the machine repeat the same area?
It may be confirming the threshold or checking an unexpected response.
Why is one eye tested at a time?
Testing separately identifies which eye contains the defect and prevents the better eye from hiding it.
Why is the test harder in one eye?
That eye may have:
- Worse disease
- More blur
- Cataract
- Dryness
- A poorer prescription
- Greater fatigue if tested second
Why does my field show a blind spot?
Every normal eye has a physiological blind spot where the optic nerve exits the retina.
Is a dark area always permanent?
No.
It may reflect disease, cataract, eyelid obstruction, poor performance or an artefact.
Can glaucoma defects improve?
True glaucomatous damage is generally irreversible, but measured results can improve because of learning, variability or removal of cataract.
What does “reliable field” mean?
It means the responses appear sufficiently consistent and interpretable. Reliability cannot be judged by one percentage alone.
Is a field with high fixation losses useless?
Not necessarily.
The blind-spot method can overestimate fixation loss. Gaze tracking and the overall pattern should also be considered.
Are high false positives worse than high false negatives?
False positives can make a damaged field look artificially normal. False negatives may reflect fatigue but also increase naturally in advanced disease.
Why does the visual field test take longer when my glaucoma is worse?
Damaged locations often require more presentations because responses are more variable.
What does an MD of –3 dB mean?
It indicates mild overall depression relative to the age-matched reference, but severity cannot be determined from MD alone.
What does VFI 90% mean?
It indicates relatively preserved summarised function, weighted towards central vision. It does not mean that exactly 10% of vision has been lost.
Can cataract make glaucoma look worse?
Yes.
Cataract may produce generalised sensitivity loss and worsen MD.
Should I use my eye drops before the test?
Usually, yes. Follow the normal schedule unless instructed otherwise.
Can pupil dilation affect the field?
A very large or small pupil may alter sensitivity. Routine glaucoma fields are often performed before dilation.
Can I wear contact lenses during the test?
Follow the clinic’s instructions. They may need to be removed so the correct trial lens can be used.
Can a field test detect a brain tumour?
It may reveal a pattern suggesting compression of the visual pathway, but imaging is required to diagnose the cause.
Can the test diagnose a stroke?
It can document a field defect consistent with a stroke, but neurological evaluation and brain imaging establish the diagnosis.
Can home or tablet fields replace clinic testing?
Portable and tablet-based systems are developing and may help with screening or monitoring, but they do not currently replace comprehensive clinical assessment for every patient.
A Practical Checklist for Patients
Before the Test
- Bring your glasses.
- Take medication as usual.
- Tell the technician about dry eye or physical discomfort.
- Ask questions before starting.
- Sit comfortably.
During the Test
- Look only at the central target.
- Blink normally.
- Press only when a light is genuinely seen.
- Do not worry about missing lights.
- Keep breathing and remain relaxed.
- Ask for a pause when needed.
After the Test
- Do not interpret the grayscale alone.
- Ask whether the result was reliable.
- Ask whether the pattern matches OCT or optic-nerve findings.
- Ask whether the test needs repeating.
- Compare results over time rather than focusing on one number.
The Bottom Line
A visual-field test measures how sensitively you can see across central and peripheral vision while looking straight ahead.
It is used to:
- Detect glaucoma
- Monitor glaucoma progression
- Assess optic-nerve and neurological disease
- Investigate retinal conditions
- Evaluate functional vision and driving fields
Standard automated perimetry presents lights of different brightness while the patient keeps looking at a central target.
Common test patterns include:
- 24-2 for routine glaucoma assessment
- 24-2C for broader testing with additional central points
- 10-2 for detailed central-field assessment
- 30-2 for selected neurological and optic-nerve conditions
- Esterman for selected binocular functional assessments
A good test requires:
- Steady central fixation
- Normal blinking
- Pressing only for genuinely seen lights
- Avoiding excessive anticipation
- Rest breaks when necessary
Visual fields naturally vary. Abnormal or unexpected results often need repeating.
Interpretation should include:
- Reliability
- Numerical sensitivity
- Total and pattern deviation
- Mean deviation
- Visual Field Index
- Defect pattern
- Comparison with previous fields
- Correlation with the optic nerve and OCT
The visual-field test is not an examination that you pass or fail. Its purpose is to build an accurate map of your vision so that real disease—and real change over time—can be detected as early as possible.
References
- American Academy of Ophthalmology. Visual Field Test and Blind Spots. Updated 2025.
- National Eye Institute. Glaucoma: Diagnosis and Visual-Field Testing. Updated November 2025.
- National Institute for Health and Care Excellence. Glaucoma: Diagnosis and Management. Guideline NG81.
- Jampel HD, et al. Assessment of Visual Function in Glaucoma: A Report by the American Academy of Ophthalmology. Ophthalmology. 2011.
- Jin E, et al. A Systematic Review of the 24-2C Test Grid. 2025.
- De Moraes CG, et al. 24-2 Visual Fields Miss Central Defects Shown on 10-2 Tests in Glaucoma Suspects, Ocular Hypertensives and Early Glaucoma. Ophthalmology. 2017.
- Wu Z, et al. Comparing 10-2 and 24-2 Visual Fields for Detecting Progressive Central Visual Loss in Glaucoma. Ophthalmology Glaucoma. 2019.
- Rao HL, et al. Role of Visual-Field Reliability Indices in Ruling Out Glaucoma. JAMA Ophthalmology. 2015.
- Heijl A, et al. False-Positive Responses in Standard Automated Perimetry. American Journal of Ophthalmology. 2022.
- Rana J, et al. Impact of the Learning Effect on Reliability Factors and Global Indices in Standard Automated Perimetry. 2023.
- Fujimoto S, et al. Reliability of the Binocular Esterman Visual-Field Test. 2024.
- Crabb DP, et al. A Practical Approach to Measuring the Visual Field Component of Fitness to Drive. British Journal of Ophthalmology. 2004.
- ZEISS Medical Technology. Humphrey Field Analyzer 3: SITA Faster and 24-2C Testing Strategies.
- Phu J, et al. The Effect of Testing Reliability on Visual-Field Sensitivity and Global Indices. Ophthalmology. 2018.
