01Purpose and principlesWhat the assessment is for and the core concepts behind it.
The visual field is the part of the surrounding scene that can be perceived while fixation remains steady. Testing it asks a different question from reading a central letter chart. A patient may have 6/6 acuity and lose a large part of their peripheral world, leading to collisions, missed food on a plate or difficulty following a line of text. Begin with the patient's description and test the two eyes separately. People often describe a homonymous defect as loss in one eye because the missing side feels like one side of the face; careful occlusion and testing clarifies the pattern.
Confrontation is a practical screening examination. Sit facing the patient at approximately arm's length with eyes at the same height. Ask them to cover one eye without pressure and look steadily into your open eye opposite their tested eye; close your other eye if comparing against your own field. Present a small target approximately midway between you, so the geometry is reasonably comparable. Your own field is only a usable reference if normal. Watch the patient's fixation throughout, since looking toward the moving stimulus can mask a defect.
Assess several positions within each quadrant rather than merely moving a large hand around the outer boundary. A finger-counting or target-identification task can sample central portions of the quadrants; a small moving target brought in from outside the field can explore a suspected boundary. Use consistent target size, distance and speed. Test near the vertical meridian when a hemianopic pattern is suspected, and compare corresponding positions across eyes. Repeat an unexpected result with clear instructions. Marked asymmetry can be detected, but subtle scotomata and early glaucomatous loss are often missed.
Field patterns help localise a lesion without proving its cause. A monocular deficit commonly arises from the retina or optic nerve. Temporal loss in both eyes suggests involvement of crossing fibres at the optic chiasm. A homonymous defect affects the same side of the visual field in each eye and indicates a lesion behind the chiasm on the opposite side. A left homonymous deficit therefore directs attention to the right retrochiasmal pathway. Quadrant patterns can refine localisation, but bedside reliability is insufficient for overconfident anatomical precision when the deficit is small or testing is limited.
Attention can also alter responses. First establish whether the patient detects stimuli presented separately on each side. Then, if appropriate during a neurological assessment, present bilateral simultaneous stimuli and ask what is seen. Failure to report one side only during simultaneous presentation is extinction, suggesting an attentional disorder rather than simply absence of visual sensitivity at that location. Neglect may include nonvisual behaviours and can coexist with hemianopia. Extend the neurological examination and seek specialist assessment instead of forcing every missed stimulus into a retinal or optic-nerve explanation.
Formal visual-field testing measures sensitivity more systematically using a defined method and is selected for the clinical question. Standard automated perimetry is important in glaucoma assessment; kinetic approaches may help map certain neurological or peripheral defects. Reliability depends on fixation, comprehension, response consistency, refractive correction and test conditions. Neither a normal bedside screen nor an unreliable automated plot is definitive. If a plausible acute field symptom suggests stroke or a retinal emergency, specialist assessment takes priority over obtaining a polished field printout.
Key points
- Confrontation screens visual fields around fixation; it is not a precise map of retinal sensitivity and cannot replace formal perimetry.
- Sit at the patient's eye level and assess each eye separately, with the patient fixing your open opposite eye and the fellow eye covered.
- Present comparable targets in all quadrants while watching fixation; use several positions and approaches rather than a single finger sweep.
- A defect confined to one eye usually points anterior to the chiasm; loss of the same side of space in both eyes suggests a contralateral retrochiasmal lesion.
- Temporal field loss in both eyes raises concern for chiasmal disease, particularly with endocrine symptoms or headache.
- Distinguish failure to see a single stimulus from extinction during simultaneous stimulation; sensory field loss and visual neglect can coexist.
- Record the side, eye, distribution and reliability of any deficit, arrange formal testing when indicated and address mobility and driving safety.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
Patients may leave food untouched, lose the beginning or end of lines or collide with objects on one side. Ask whether the problem remains when either eye is covered and perform monocular testing.
A new shadow or curtain after flashes and floaters suggests a retinal process. The visible extent may change, and a normal central acuity score does not remove the need for urgent retinal examination.
Loss toward the outer side of each eye can be subtle in daily life. Ask about headache and endocrine symptoms, assess acuity and pupils, and arrange assessment for possible chiasmal disease.
Eye movements toward the target, fatigue, confusion, language difficulties and severe visual impairment can create misleading results. Document which parts were testable and adapt the examination without inventing a normal field.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Monocular quadrant confrontationFirst step - Why
- Screen for reproducible asymmetry in visual function around fixation.
- Interpretation and limitations
- Keep the target geometry consistent and watch the patient's gaze. Record findings for each eye, including sampled quadrants and limitations; a grossly full result does not exclude small or shallow defects.
- 02
Target movement across a suspected boundary - Why
- Clarify the distribution of an apparent field deficit.
- Interpretation and limitations
- Repeat from different starting positions with a small consistent stimulus and compare both eyes. A coarse bedside outline guides localisation but should not be presented as a precise perimetric measurement.
- 03
Single and simultaneous bilateral stimulation - Why
- Differentiate a sensory field deficit from an additional attentional abnormality.
- Interpretation and limitations
- Interpret extinction only after confirming detection on each side separately. Neglect and field loss may overlap, so the result requires a broader neurological and functional assessment.
- 04
Formal perimetry with reliability review - Why
- Measure visual-field sensitivity using a standardised specialist method.
- Interpretation and limitations
- Choose the programme and technique for the suspected disease, inspect reliability information and correlate the plot with examination. Do not postpone emergency referral to obtain routine automated testing.
- 05
Retinal, optic-nerve and neurological localisation - Why
- Identify the lesion associated with a confirmed or strongly suspected field defect.
- Interpretation and limitations
- Acuity, pupils, colour, optic-disc examination and the neurological findings determine whether retinal examination, neuroimaging or other specialist investigations are required.
04Clinical next stepsHow the result changes management or prompts escalation.
01Bedside techniqueScreen both monocular fields carefullyFirst stepA visual complaint or neurological examination requires assessment beyond central acuity.+
- 1Explain fixation and the response required, position your eyes at the patient's level and cover the untested eye without pressure.
- 2Present targets in multiple positions in every quadrant, maintaining comparable distance and checking that the patient does not follow the stimulus.
- 3AlternativeRepeat any apparent defect with a clear alternative presentation and record the affected eye and side of visual space.
02Acute deficitEscalate before definitive field mappingDefinitiveEscalationThe field change is sudden or accompanied by an evolving retinal or neurological symptom.+
- 1Establish the onset or last known normal time and assess associated weakness, speech disturbance, headache, flashes, floaters and ocular pain.
- 2Arrange immediate stroke assessment for an acute homonymous or neurological pattern, or urgent emergency eye assessment for a likely retinal or optic-nerve presentation.
- 3Communicate acuity and pupil results with the field pattern and testing limitations, and provide safe assistance with movement and transport.
03Ongoing assessmentConfirm stable defects and support functionA nonacute or uncertain deficit remains after the initial clinical evaluation.+
- 1Arrange appropriate formal perimetry and specialist assessment, choosing urgency from symptoms and progression rather than from the bedside test alone.
- 2Review the results alongside structural examination and repeat unreliable measurements with suitable communication, correction and supervision.
- 3Discuss reading, falls and navigation, involve rehabilitation services where needed and assess driving against the relevant licensing authority's requirements.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Describe whether the defect is monocular, bitemporal or homonymous and draw or label its distribution clearly, always from the patient's visual perspective.
- Document test reliability and repeat findings after meaningful clinical change, without claiming that a single confrontation comparison quantifies progression.
- Check that patients with field loss can navigate unfamiliar surroundings and access written information, offering scanning strategies and specialist rehabilitation assessment.
- Advise patients with a newly significant field defect to stop driving pending assessment; apply DVLA guidance in Great Britain and DVA guidance in Northern Ireland.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Fixation is part of the test
A patient who turns their eyes toward each target is demonstrating that the target can eventually be found, not that it was visible at the intended field location. Re-establish fixation before accepting the response.
Describe space before naming anatomy
Writing 'left eye field loss' can mean left monocular loss or loss of the left side of space. Specify each eye's temporal and nasal findings or use a labelled diagram to prevent an incorrect referral interpretation.
An intact pupil response has limits
A retrochiasmal visual lesion may leave pupil responses relatively normal. Preserved light reactions alongside a homonymous deficit should prompt localisation beyond the anterior afferent pathway rather than dismissal of the symptom.
Perimetry is a clinical measurement
Automated testing produces numbers and maps, but these still depend on how well the patient understands and performs the task. Correlation with history, structural findings and repeated reliable tests prevents overdiagnosis from artefact.
07Common pitfallsFrequent interpretation and management errors.
- 01
Relying on normal distance acuity or a normal FAST result to dismiss a sudden field deficit that may represent an isolated visual stroke.
- 02
Testing both eyes together and then labelling a deficit monocular without establishing the separate distribution in each eye.
- 03
Allowing the patient to track a moving target and documenting full fields despite failure to maintain fixation.
- 04
Treating confrontation as adequate glaucoma exclusion or as the formal visual-field assessment required for a driving decision.