Visual Field Defects

How the visual field works

Each eye sees about 90 to 100 degrees to the side and 60 degrees toward the nose, and the two fields overlap in the center. Light from the right half of your world lands on the left half of each retina, and vice versa.

The fibers from each retina travel in the optic nerve. At the optic chiasm, just above the pituitary gland, fibers from the nasal (inner) half of each retina cross to the other side. From there, the optic tracts and optic radiations carry information from the opposite half of the world to the occipital lobe at the back of the brain.

This wiring means each type of damage leaves a recognizable pattern.

Types of visual field defects

Symptoms

Many field defects go unnoticed, because the brain fills in gaps and the other eye covers for a defect in one eye. Glaucoma can destroy a large part of the field before a person is aware of it. When people do notice, they describe:

• bumping into door frames or people on one side
• missing food on one side of the plate
• difficulty reading, losing the start or end of lines
• not seeing cars or pedestrians coming from one side
• a dark, blurry or missing patch in vision
• trouble finding things that are "right in front of you"
• trouble driving, especially changing lanes

Causes

Eye causes

• glaucoma
• retinal detachment, retinal vein or artery occlusion
• retinitis pigmentosa and other inherited retinal diseases
• macular degeneration (central field)
• toxic or nutritional damage, for example from certain medicines

Optic nerve causes

• optic neuritis, often linked to multiple sclerosis
• ischemic optic neuropathy, including giant cell arteritis
• optic disc swelling from pseudotumor cerebri (idiopathic intracranial hypertension)
• compression by tumors, thyroid eye disease

Brain causes

• stroke, the most common cause of homonymous hemianopia in adults
• brain tumors, including pituitary adenomas and meningiomas
• head injury
• brain infections, MS and other inflammatory conditions

Temporary field defects

A migraine aura can cause a shimmering zigzag line or blind spot lasting 5 to 60 minutes. A transient blackout of vision in one eye (amaurosis fugax) can warn of a stroke and needs urgent assessment.

How visual field defects are diagnosed

1. Confrontation test: the examiner sits facing you and checks whether you can see fingers in each quarter of your vision. Quick but only detects larger defects.
2. Automated perimetry (such as Humphrey 24-2): you look at a central point and press a button when you see small flashes of light. It maps the field precisely and tracks changes over time.
3. Goldmann kinetic perimetry: moving lights mapped by an examiner, useful for very constricted fields.
4. Amsler grid: a square grid used to check central vision for distortion or missing areas.
5. Eye exam and optical coherence tomography (OCT): examine the retina and optic nerve.
6. MRI of the brain and orbits: when the pattern points to the optic nerve, chiasm or brain.
7. Blood tests: such as inflammatory markers for giant cell arteritis, and hormone tests for pituitary tumors.

Treatment

Treatment depends on the cause:

• Glaucoma: pressure-lowering eye drops, laser or surgery to stop further loss (lost field does not return).
• Retinal detachment: urgent surgery to reattach the retina.
• Stroke: emergency stroke treatment; some field recovery can occur over 3 to 6 months.
• Pituitary tumors: medicine or surgery; vision often improves after the pressure on the chiasm is relieved.
• Optic neuritis: often improves on its own; steroids may speed recovery.
• Raised brain pressure: weight loss, medicines and sometimes surgery to protect the optic nerves.

Living with permanent field loss

• Visual scanning training: learning to move the eyes deliberately toward the blind side
• Prism glasses: shift images from the missing side into the seeing field
• Reading strategies: using a ruler or finger to find line edges
• Low vision services: magnifiers, lighting and home adaptations
• Driving: many field defects, particularly homonymous hemianopia, may disqualify you from driving. Rules vary by US state and country; ask your eye doctor and licensing authority.

Frequently asked questions

What are the types of visual field defects?

Main types include central scotoma, arcuate defects (glaucoma), altitudinal defects, tunnel vision, bitemporal hemianopia (pituitary tumors), homonymous hemianopia (stroke or brain injury) and quadrantanopia. The pattern helps doctors locate the damage along the visual pathway.

What is the most common cause of visual field loss?

Glaucoma is the most common cause of gradual visual field loss, usually starting in the side vision without symptoms. Stroke is the most common cause of sudden loss of the same half of vision in both eyes.

What does a visual field test show?

It maps how much you can see around a central point and how sensitive each area is. It detects blind spots and missing areas, shows their pattern, and is repeated over time to see whether conditions like glaucoma are stable or getting worse.

Can visual field loss be restored?

Sometimes. Field loss from retinal detachment, pituitary tumors pressing on the nerves, optic neuritis and some strokes can partly or fully recover with treatment. Loss from glaucoma and long-standing nerve damage is usually permanent, but treatment stops further loss.

Can I drive with a visual field defect?

It depends on the size and type of defect and where you live. Many licensing authorities require a minimum field width, and homonymous hemianopia often disqualifies people from driving. Your eye doctor can test your field and advise on local requirements.