[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Ophthalmology](https://durgical.com/en/ophthalmology/) › [Approach by symptom](https://durgical.com/en/ophthalmology/areas/approach/) › Localising a visual field defect

# Localising a visual field defect

- Clinical approach

The shape of a field defect shows the lesion: one eye is the eye or optic nerve, both temples the chiasm, the same side in both eyes the brain behind.

Updated Nov 5, 2026

**See it in 3D:** [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/) · [Optic chiasm](https://durgical.com/en/anatomy/optic-chiasm/) · [Geniculate bodies](https://durgical.com/en/anatomy/lateral-geniculate-body/) · [Visual cortex](https://durgical.com/en/anatomy/cuneus/)

## Key points

- One eye = in front of the chiasm.
- Bitemporal = chiasm (pituitary).
- Homonymous = behind the chiasm, opposite side.
- Pie in the sky = temporal lobe; macular sparing = occipital.

## What it is

Each part of the visual pathway produces a typical field defect. In front of the chiasm, defects affect one eye: a central scotoma in optic neuritis, an altitudinal defect in ischaemic optic neuropathy, an arcuate defect in glaucoma. At the chiasm the crossing nasal fibres are hit, giving a bitemporal hemianopia. Behind the chiasm, the defect is homonymous (the same side in both eyes) and on the side opposite the lesion; the more posterior, the more alike the defects in the two eyes.

## Red flags

- New homonymous hemianopia of sudden onset: stroke, a stroke code.
- Bitemporal defect with sudden headache, vomiting or eye-movement palsy: pituitary apoplexy.
- Bitemporal defect with gradual onset: pituitary adenoma, craniopharyngioma (children) or meningioma.
- Field defect with papilloedema.
- A patient who drives or operates machinery.

## Step-by-step approach

- Test each eye separately by confrontation, then formally with automated perimetry.
- Decide whether the defect is in one eye or both.
- If both: does it respect the vertical midline, and is it on both temporal sides (chiasm) or on the same side (behind the chiasm)?
- Judge congruity: very similar defects in the two eyes point to the occipital lobe.
- Correlate with the rest of the neurological exam and image the suspected level.

## Field defects and where the lesion is

| Defect | Site | Typical cause |
| --- | --- | --- |
| [Loss in one eye, central scotoma](https://durgical.com/en/conditions/optic-neuritis/) | Optic nerve | Optic neuritis, toxic optic neuropathy |
| Upper or lower half of one eye (altitudinal) | Optic nerve head or retina | Ischaemic optic neuropathy, branch artery occlusion |
| [Arcuate defect](https://durgical.com/en/conditions/open-angle-glaucoma/) | Optic nerve head | Glaucoma |
| [Bitemporal hemianopia](https://durgical.com/en/conditions/pituitary-adenoma/) | Chiasm | Pituitary adenoma |
| Homonymous hemianopia, incongruous | Optic tract | Tumour, demyelination |
| [Superior homonymous quadrantanopia](https://durgical.com/en/conditions/ischaemic-stroke/) | Temporal lobe (Meyer loop) | Stroke, tumour |
| [Inferior homonymous quadrantanopia](https://durgical.com/en/conditions/ischaemic-stroke/) | Parietal lobe | Stroke, tumour |
| [Congruous homonymous hemianopia, macula spared](https://durgical.com/en/conditions/ischaemic-stroke/) | Occipital cortex | Posterior cerebral artery stroke |

## Keys to the differential

- Macular sparing in occipital stroke happens because the macular cortex has a dual blood supply from the middle and posterior cerebral arteries.
- Pituitary adenomas compress the chiasm from below, so the superior temporal quadrants are usually lost first.
- Patients with homonymous hemianopia often complain of trouble reading or bumping into things on one side, not of loss in one eye.

## Next step / Initial management

- Sudden homonymous loss: emergency stroke pathway with brain imaging.
- Bitemporal loss: MRI of the pituitary region and a pituitary hormone panel (prolactin, IGF-1, morning cortisol, thyroid tests); refer to neurosurgery and endocrinology.
- Suspected pituitary apoplexy: emergency imaging, corticosteroid replacement and neurosurgery.
- Document the defect with automated perimetry for follow-up, and advise on driving according to the national rules.

## Test yourself

Think of the answer, then tap the question to see it.

## Where is the lesion in a bitemporal hemianopia?

At the optic chiasm, where the crossing nasal fibres from both eyes are compressed, most often by a pituitary adenoma.

## Which field defect does a temporal lobe lesion cause?

A contralateral superior homonymous quadrantanopia, from damage to Meyer's loop.

## Why is the macula often spared in occipital stroke?

Because the occipital pole has a dual blood supply from the posterior and middle cerebral arteries.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/ophthalmology/localising-a-visual-field-defect/)

## Elsewhere in DurgiPedia

- [The visual pathway, pupillary reflexes and eye movements](https://durgical.com/en/physiology/the-visual-pathway-pupillary-reflexes-and-eye-movements/)
- [Eye exam: visual acuity, visual fields and eye movements](https://durgical.com/en/clinical-exam/eye-exam-visual-acuity-visual-fields-and-eye-movements/)

## Connections

## See it in 3D 4

The structures of Durgical's 3D anatomy where it is found.

- [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/)
- [Optic chiasm](https://durgical.com/en/anatomy/optic-chiasm/)
- [Geniculate bodies](https://durgical.com/en/anatomy/lateral-geniculate-body/)
- [Visual cortex](https://durgical.com/en/anatomy/cuneus/)

## Related 4

- [Visual fields: confrontation, Amsler grid and perimetry](https://durgical.com/en/ophthalmology/visual-fields-confrontation-amsler-grid-and-perimetry/)
- [Sudden painless visual loss](https://durgical.com/en/ophthalmology/sudden-painless-visual-loss/)
- [Gradual visual loss in adults](https://durgical.com/en/ophthalmology/gradual-visual-loss-in-adults/)
- [The swollen optic disc: papilloedema or not](https://durgical.com/en/ophthalmology/the-swollen-optic-disc-papilloedema-or-not/)

## Related conditions 5

- [Pituitary adenoma](https://durgical.com/en/conditions/pituitary-adenoma/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)
- [Optic neuritis](https://durgical.com/en/conditions/optic-neuritis/)
- [Open-angle glaucoma](https://durgical.com/en/conditions/open-angle-glaucoma/)
- [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/)

[← All of ophthalmology](https://durgical.com/en/ophthalmology/)

Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once.

Sources: [Neuroanatomy, Visual Pathway](https://www.ncbi.nlm.nih.gov/books/NBK553189/) (StatPearls Publishing (NCBI Bookshelf), 2026); [Neuroanatomy, Optic Chiasm](https://www.ncbi.nlm.nih.gov/books/NBK542287/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Humphrey Visual Field](https://www.ncbi.nlm.nih.gov/books/NBK585112/) (StatPearls Publishing (NCBI Bookshelf), 2025).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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Source: https://durgical.com/en/ophthalmology/localising-a-visual-field-defect/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/ophthalmology/localising-a-visual-field-defect/