Understanding Visual Field Assessment for Student Nurses
Learn how to recognise visual field changes, compare vision with the patient's normal baseline and understand when sudden visual disturbance may indicate neurological deterioration.
What is a visual field?
The visual field is the area a person can see while looking straight ahead. Neurological disease or injury can affect part of this field even when the eyes themselves appear normal.
What is directly ahead?
Central vision helps a person focus on what they are looking at directly.
What can be seen around the edges?
Peripheral vision helps detect objects and movement outside the centre of gaze.
Vision depends on the brain
Visual pathways extend from the eyes through the nervous system to the brain, so neurological problems can alter visual fields.
What might a visual field problem look like?
Not noticing one side
The patient may repeatedly fail to notice people or objects on one side.
Bumping into surroundings
A new tendency to collide with furniture or door frames may reflect impaired visual awareness.
Parts of text may be missed
The patient may struggle to see words or lines on one side of a page.
Food may be left untouched
A patient may repeatedly leave food on one side of the plate because it is not being noticed.
The patient may report missing vision
They may describe a dark area, missing section or unusual visual disturbance.
Timing matters
A new visual field change is more concerning than a stable, long-standing deficit.
Compare visual awareness systematically
Visual field assessment should be performed using the technique taught and approved in your clinical area and within your level of competence. The aim is to recognise asymmetry or change rather than diagnose the neurological lesion.
Establish baseline
Ask whether the patient has existing visual impairment, wears glasses or has a known visual field problem.
Observe function
Notice whether the patient sees and responds to objects from both sides.
Compare sides
Where appropriate, use the locally taught method to compare visual awareness in corresponding parts of the field.
Document the change
Describe what the patient can or cannot see and whether the finding differs from previous observations.
Visual change can form part of a focal neurological pattern
Any limb weakness?
Visual disturbance with new one-sided weakness increases concern about acute neurological deterioration.
Has communication changed?
New aphasia or dysarthria may occur alongside visual changes.
Any numbness?
Sudden sensory loss and visual disturbance may form part of the same focal neurological presentation.
Are movements accurate?
Poor coordination may accompany acute visual or neurological changes.
Is mobility different?
Visual field loss can affect safe walking and may occur with other neurological causes of imbalance.
Is alertness changing?
Visual disturbance with reduced consciousness requires urgent assessment.
New visual field disturbance associated with weakness, sensory change, speech difficulty or poor coordination should be escalated urgently.
When visual changes need urgent escalation
- Sudden new loss of part of the visual field.
- Sudden inability to see normally from one side.
- Visual change with new facial or limb weakness.
- Visual change with aphasia or dysarthria.
- Visual change with new numbness or sensory loss.
- Visual disturbance with severe new imbalance or poor coordination.
- Visual change following a head injury.
- Visual disturbance associated with reduced consciousness.
Not seeing and not attending are not identical
A patient may fail to respond to one side because of visual field loss, reduced attention to that side, or another neurological problem. Distinguishing these can require specialist assessment.
Part of the visual field is missing
The patient's visual pathway may prevent information from part of the field being seen normally.
Attention to one side is reduced
The patient may fail to attend to one side despite the eyes and visual pathways not fully explaining the behaviour.
Observe and report
Your priority is to recognise the functional change and communicate it clearly rather than attempting to diagnose the exact cause.
Visual field changes can create immediate risk
Mobility can become unsafe
The patient may not see hazards, furniture or people approaching from the affected side.
Important items may be missed
Food, drinks, call bells and personal items can be overlooked if placed in an affected area.
Follow the care plan
Use locally recommended mobility and communication strategies while awaiting further assessment.
Place visual change within the wider assessment
Airway
Assess airway patency and respond immediately to compromise.
Breathing
Assess respiratory rate, oxygen saturation, pattern and work of breathing.
Circulation
Assess pulse, blood pressure and perfusion within the overall clinical picture.
Disability
Assess consciousness, pupils, vision, strength, sensation, speech, coordination and blood glucose according to local practice.
Exposure
Look for injury, illness or other findings that may explain deterioration while maintaining dignity.
Escalate
Report significant new visual or neurological change promptly and follow the relevant local pathway.
Recognising sudden visual change
Example
A patient who was reading normally earlier begins repeatedly missing objects on the left side of their bedside table.
They tell you that part of their vision seems to have disappeared. You also notice new weakness in their left arm.
You recognise the pattern: sudden visual disturbance + new focal limb weakness.
You perform a structured assessment, establish when the patient was last known to be at their normal neurological baseline and escalate immediately according to the local emergency pathway.
Describe what the patient is missing
Example escalation
“I'm concerned about Mrs Ahmed. She was reading normally earlier but has suddenly started missing objects on her left side and reports that part of her vision has disappeared. She also has new left arm weakness.”
This communicates the baseline, sudden visual change, side affected and associated neurological deficit.
Visual assessment errors to avoid
- Assuming every visual problem originates in the eye.
- Failing to establish the patient's usual vision.
- Ignoring a sudden functional change such as missing objects on one side.
- Failing to connect visual change with weakness, speech or sensation.
- Documenting only “poor vision” without describing what changed.
- Ignoring the effect of visual loss on falls risk.
- Trying to diagnose visual field loss or neglect without appropriate assessment.
- Waiting for visual symptoms to resolve before escalating an acute change.
Observe → compare → connect → escalate
Notice visual behaviour
Look for objects being missed, collisions, reading difficulty or reported loss of vision.
Check baseline and neurological signs
Establish whether the change is new and connect it with movement, sensation, speech, balance and coordination.
Report acute visual changes
Describe exactly what changed, when it changed and what other focal neurological findings are present.
Build a more complete neurological assessment
Visual field changes become more meaningful when connected with pupils, speech, strength, sensation, coordination, balance and the patient's normal neurological baseline.
Explore Clinical Confidence →