One side of space, rather than one eye
Homonymous hemianopia affects the same side of the visual world in each eye. It comes from damage in the brain’s visual pathways, rather than simply a problem in the right or left eye. Stroke is one possible cause, but the cause must be established clinically. [1]
People may miss objects on the affected side, have difficulty reading or navigating, or be incompletely aware of the loss. Visual neglect is an attention problem that can coexist, but is not the same thing as the field defect. [1]
Same side
Right-side or left-side loss occurs in both eyes.
Awareness varies
A person may not experience a literal dark half-screen.
Different assessments
Field loss and visual attention need distinct consideration.
Terms in this guide
- Homonymous
- Affecting the corresponding side of the visual world through both eyes.
- Macular sparing
- Preserved central visual function within a field defect.
One condition. Different experiences.
These original schematics mark an affected side and an example of central sparing. They are not photographs of perception or predictions of recovery.
Original VisualSim schematic illustrations, informed by the cited clinical descriptions. These are not study figures, patient recordings or validated severity levels. Clinical basis: source 1. Artwork: © VisualSim; see image provenance.
Visual pathways, fields and central sparing
Visual information from corresponding halves of the two eyes is processed by the opposite side of the brain. The location and extent of injury influence the field pattern. Some people retain central visual function, described as macular sparing. [2]
Blanking part of a picture is a teaching convention. A person’s awareness, adaptation, eye movements and attention are not recreated by the overlay. A simulation cannot determine whether someone is safe to drive or navigate independently.
What can look similar?
One-eye sight loss
A problem confined to one eye differs from loss of the same side of the world through either eye.
Visual neglect
Neglect involves attention to space and can coexist with a field defect. [1]
Other field patterns
Outer-half or quarter-field defects have different descriptions and possible causes; this guide keeps the homonymous pattern.
Similar-looking symptoms can have different causes. A matching picture cannot establish a diagnosis.
What an assessment may involve
Assessment can include visual-field testing, eye-movement and attention assessment and neurological investigation appropriate to the cause. Explain reading, mobility and awareness difficulties, not only what a shaded picture looks like. [1]
The European Stroke Organisation guideline considers screening, assessment and several types of visual impairment after stroke. Its scope is broader than hemianopia: eye movements, visual attention and other visual functions may need separate consideration in a rehabilitation plan. [4]
- Map the descriptionWhich side of the scene is difficult through either eye?
- Assess function and attentionAsk about reading, mobility, attention and the measured field.
- Plan rehabilitationSet practical goals and understand any legal or safety assessment requirements.
What may help—and what is still being studied
Rehabilitation can include strategies to improve awareness and performance on daily tasks. It is important to distinguish compensation from restoring a damaged visual field. Treatments should be assessed by the outcomes that matter to the person. [3]
The 2025 SEARCH trial compared visual scanning training with sham training after stroke. Both groups improved, without a significant between-group difference. This does not mean nobody benefits from rehabilitation; it limits claims about that specific training protocol. [3]
What this can mean for daily life
Describe the missed information
Use examples such as leaving part of a line unread or missing objects on one side of a desk.
Plan practical support
Ask an orthoptist, occupational therapist or rehabilitation team about individual goals. The simulator is not a driving assessment.
Bring a clearer description to your appointment
Choose the questions you want to discuss. These choices stay in this page’s memory.
Research, with the context left in
A visual-field change, improved scanning and improved quality of life are different outcomes. Keep them separate when interpreting rehabilitation claims.
What the evidence supports
Rehabilitation research distinguishes task compensation, optical substitution and restoration of the visual field. The 2025 SEARCH trial is essential context: a particular scanning-training protocol did not outperform its active sham comparison. This does not justify withdrawing individualized rehabilitation.
How we select and interpret researchRowe et al.: SEARCH trial
Scanning and sham slow-tracking groups both improved, with no significant between-group difference on the reported primary or secondary outcomes at 26 weeks.
Limits and applicability: Only 104 had primary-outcome data. No untreated control separates training, recovery and support effects. Results do not show that all rehabilitation is useless or that scanning restores the missing field.
How to read this evidence: A strong comparative design tests this particular scanning program; missing outcomes and an active comparator limit interpretation.
Pollock et al.: Interventions for visual field defects after stroke
Evidence was insufficient for firm conclusions on daily-activity benefits or field restoration. Scanning had limited quality-of-life evidence; prism evidence was uncertain and headaches were reported.
Limits and applicability: Search ended in May 2018 and predates SEARCH. Small studies, inconsistent outcomes and sparse adverse-event reporting restrict conclusions.
How to read this evidence: Systematic methods are valuable, but the review judged much of the underlying evidence limited and uncertain.
Canadian Stroke Best Practices: Visual and visual-perceptual impairment
Addresses visual problems, eye movements, fields, neglect, functional goals and referral within stroke rehabilitation.
Limits and applicability: Recommendation strength varies across interventions. Hemianopia and visual neglect are different problems; treatment should not be copied between them without assessment.
How to read this evidence: A practical guideline separates screening, assessment and tailored rehabilitation from a single treatment claim.
Horton, Economides and Adams: The mechanism of macular sparing
Explains how preserved central visual cortex can support macular sparing and why unstable fixation can create misleading field maps.
Limits and applicability: Does not predict an individual’s recovery or establish that training restores damaged visual cortex. Simulator pixels are not measured visual degrees.
How to read this evidence: Useful mechanistic explanation with careful discussion of testing artifacts; not a treatment trial.
Questions researchers still need to answer
- Which components of scanning, tracking, clinician contact and information produce meaningful functional gains?
- How should studies measure reading, mobility, fatigue and quality of life alongside carefully fixation-controlled field testing?
- Which strategies help when field loss coexists with neglect, eye-movement problems or cognitive difficulties?
These are editorial interpretations, not formal GRADE ratings or independent clinical review. A large sample, recent date or well-known publisher does not make every claim certain.
Trusted places to go next
Selected clinical references, research and support organizations. Each link explains who it is for.
NANOS: homonymous hemianopia
Clinical explanation and patient/clinician brochures.
British and Irish Orthoptic Society
Find information about orthoptic assessment and vision after stroke.
American Stroke Association: visual disturbances
Understanding visual difficulties and recovery after stroke.
SEARCH trial
Methods and results of the scanning-training comparison.
European Stroke Organisation guideline
Screening, assessment and management of visual impairment after stroke.
Organizations & ways to connect
Selected charities, professional organizations and communities, with their scope and region. Official pages checked 24 October 2026. Community discussions are peer support; each external service has its own privacy and moderation rules.
North American Neuro-Ophthalmology Society
Patient and clinician information about same-side field loss, causes, function and assessment. This is not a peer-support community.
British and Irish Orthoptic Society
Separate patient resources for visual fields, eye movements, inattention, perception and driving after stroke or brain injury.
Stroke Association
Staff-moderated conversation for survivors, carers and families. It is broader than visual-field loss; peer contributions are not medical advice.
Connections listed by the organization.
American Stroke Association
Information, local support-group routes and the AHA/ASA Support Network. Peers can discuss living after stroke but do not replace a vision or rehabilitation assessment.
Connections listed by the organization.
Headway: the brain injury association
Practical brain-injury support and an organization-linked HealthUnlocked forum. Particularly relevant when brain injury is the cause; peer advice is not clinical guidance.
Connections listed by the organization.
RNIB
Practical and emotional support, accessible technology, employment guidance and regional Connect communities. Peer discussions complement clinical care and are not medical advice.
Connections listed by the organization.
Questions you may still have
Is right hemianopia blindness in the right eye?
No. It concerns the right side of the visual world in both eyes. [1]
Is the dark overlay what everyone sees?
No. It marks a location schematically. Awareness and adaptation differ.
Can training restore the missing field?
Compensation, task performance and field restoration are different claims. Ask which outcome a proposed treatment has evidence for.
Sources, image credits and review status
Compiled by VisualSim from clinical references and published research. Sources checked 24 October 2026. Independent clinical review has not been recorded; no named clinical reviewer or clinical validation is claimed. Research evidence and its limitations are linked below.
- North American Neuro-Ophthalmology Society. Homonymous hemianopia. Clinical information; sources checked 24 October 2026.
- Horton et al. The Mechanism of Macular Sparing (2021). Clinical information; sources checked 24 October 2026.
- Rowe et al. Scanning Eye trAining as a Rehabilitation Choice for Hemianopia after stroke: SEARCH (2025). Clinical information; sources checked 24 October 2026.
- European Stroke Organisation. Guideline on visual impairment in stroke (2025). Clinical information; sources checked 24 October 2026.
- Rowe et al.: SEARCH trial (2025). Multicenter double-blind randomized trial; 161 randomized adults, 4–26 weeks after stroke
- Pollock et al.: Interventions for visual field defects after stroke (2019). Cochrane systematic review; 20 studies, 732 randomized participants
- Canadian Stroke Best Practices: Visual and visual-perceptual impairment (2025). Stroke rehabilitation guideline
- Horton, Economides and Adams: The mechanism of macular sparing (2021). Anatomical and neurophysiological research review
The simulator helps people communicate an experience. It cannot diagnose a condition, measure a visual field, or establish that someone is safe to drive.