Visual Field Defects

Overview

A visual field defect is a loss of vision in part of the area you can normally see while looking straight ahead. Rather than affecting how sharp your vision is, these defects create blind spots or missing zones, which may be in the center, the sides (peripheral vision), or one half of the field of view.

The visual field depends on the eyes, the optic nerves, and the visual pathways through the brain. A problem anywhere along this path can cause a field defect, and the pattern of loss often helps point to where the problem lies. Some causes, such as stroke, are emergencies, so sudden visual field loss should be treated urgently.

The way the visual pathway is wired means the pattern of loss often reveals where the problem is. For example, damage in front of where the optic nerves cross tends to affect one eye, while damage behind that point tends to affect the same half of the field in both eyes. Mapping the defect carefully therefore does more than measure vision; it gives doctors important clues about the location and nature of the underlying cause.

Symptoms

Visual field defects can be subtle or obvious, depending on their size and location:

• Missing or dim areas within your field of view
• Loss of side (peripheral) vision, sometimes described as tunnel vision
• Loss of one half of the visual field in each eye
• A blind spot in the center of vision
• Bumping into objects or missing things to one side
• Difficulty reading, driving, or judging where things are

Because some defects develop gradually, they may be noticed only during an eye exam. Sudden loss of part of the visual field can be a stroke and needs emergency care.

Causes

Visual field defects can arise from problems anywhere along the visual pathway:

• Glaucoma: A leading cause of gradual peripheral vision loss.
• Retinal conditions: Such as retinal detachment or macular disease.
• Optic nerve problems: Including inflammation or damage from pressure.
• Stroke or brain injury: Affecting the visual pathways, often causing loss of one half of the field.
• Brain tumors: Such as a pituitary adenoma pressing on the visual pathway.
• Migraine: Causing temporary visual disturbances.

Risk Factors

• Older age
• Glaucoma or a family history of it
• High blood pressure, diabetes, and other stroke risk factors
• Eye diseases affecting the retina or optic nerve
• Brain tumors or prior brain injury
• History of migraine with visual symptoms

Diagnosis

Evaluation aims to map the defect and find its cause:

• Visual field testing (perimetry): Maps exactly where vision is reduced or missing; the pattern helps locate the problem.
• Eye examination: Including the retina and optic nerve.
• Imaging: MRI or CT of the brain and eye structures when a nerve, brain, or tumor cause is suspected.
• Other tests: Such as eye pressure measurement for glaucoma.

Treatment

Treatment depends on the underlying cause:

• Treating the cause: Such as lowering eye pressure in glaucoma, emergency stroke care, repairing a detached retina, or treating a tumor.
• Vision rehabilitation: Strategies, training, and devices to help people adapt to permanent field loss and stay safe and independent.
• Monitoring: Repeat field testing to track stability or progression.
• Safety guidance: Including advice about driving, which may be restricted with significant field loss.

Catching and treating the cause early offers the best chance of preserving vision.

Prevention

Not all field defects can be prevented, but risk can be reduced by:

• Having regular eye exams, especially with a family history of glaucoma
• Controlling blood pressure, blood sugar, and other stroke risk factors
• Not smoking
• Seeking prompt care for any sudden vision change
• Following treatment for known eye or neurological conditions

When to See a Doctor

See an eye doctor for any new or gradually worsening loss of side or central vision. Seek emergency care right away if you have:

• Sudden loss of part of your visual field, especially on one side
• Sudden vision loss with weakness, numbness, or trouble speaking (possible stroke)
• A curtain or shadow moving across your vision (possible retinal detachment)
• Sudden vision loss with eye pain, redness, or severe headache

Related Topics

Frequently Asked Questions

References

1. National Eye Institute (NEI). Glaucoma.
2. American Academy of Ophthalmology. Visual Field Test.
3. MedlinePlus, U.S. National Library of Medicine. Visual field.
4. National Institute of Neurological Disorders and Stroke (NINDS). Stroke.