Visual Field – Definition, Defects & Diagnosis
The visual field is the entire area that an eye can perceive without moving the gaze. Defects in the visual field may indicate eye or neurological conditions.
Wissenswertes über "Visual Field"
The visual field is the entire area that an eye can perceive without moving the gaze. Defects in the visual field may indicate eye or neurological conditions.
What Is the Visual Field?
The visual field refers to the complete extent of what an eye can see at any given moment without moving the gaze. It encompasses both central vision and peripheral (side) vision. Under normal conditions, the visual field of a single eye extends approximately 60 degrees upward, 70–75 degrees downward, 100 degrees outward (temporal), and 60 degrees inward (nasal). Combined, both eyes produce a binocular visual field of approximately 200 degrees horizontally.
Importance of the Visual Field
The visual field is essential for spatial orientation, safe driving, reading, and many everyday tasks. Changes or losses in the visual field can significantly impact quality of life and are often a critical diagnostic indicator for diseases of the eye or the nervous system.
Causes of Visual Field Defects
Visual field defects (also called scotomas or visual field loss) can result from various conditions:
- Glaucoma: One of the most common causes; elevated intraocular pressure damages the optic nerve, initially causing peripheral visual field loss.
- Retinal diseases: Including retinal detachment, age-related macular degeneration, or retinal vascular occlusions.
- Optic nerve disorders: Such as optic neuritis (inflammation of the optic nerve), frequently associated with multiple sclerosis.
- Cerebral causes: Stroke, brain tumors, or injuries along the visual pathway can cause characteristic defects such as hemianopia (loss of half the visual field).
- Migraine with aura: Temporary visual disturbances in the form of scintillating scotomas (flickering blind spots).
- Raised intracranial pressure: Can compress the optic nerve and restrict the visual field.
Symptoms and Perception of Visual Field Defects
Patients often notice visual field defects only at a late stage, as the brain tends to unconsciously fill in missing information. Common signs include:
- Dark or gray patches in the field of vision (scotomas)
- Tunnel vision (severe restriction of peripheral vision)
- Bumping into objects or people on one side
- Difficulty reading or recognizing faces
- Flickering or flashes of light (in migraine aura)
Diagnosis: Perimetry
The primary diagnostic tool for assessing the visual field is perimetry. The patient fixates on a central point while light stimuli are presented at various positions within the visual field. Based on the responses of the patient, a detailed map of the visual field is generated.
Types of Perimetry
- Automated static perimetry: The gold standard in modern ophthalmology; precise, reproducible, and standardized (e.g., Humphrey Field Analyzer).
- Kinetic perimetry (Goldmann perimetry): A moving light stimulus is brought from the periphery toward the center; particularly suitable for patients with limited cooperation ability.
- Confrontation test: A simple bedside screening method requiring no specialized equipment.
Treatment
Treatment of visual field defects depends on the underlying cause:
- Glaucoma: Reduction of intraocular pressure through eye drops, laser treatment, or surgery.
- Retinal diseases: Depending on the cause, laser therapy, intravitreal injections (injections into the eye), or surgery.
- Optic neuritis: Corticosteroid therapy to accelerate recovery.
- Cerebral causes: Treatment of the underlying condition (e.g., stroke management); additionally, visual rehabilitation programs may help patients partially compensate for lost areas.
Some visual field defects are permanent; therefore, early diagnosis and timely treatment are critical to prevent further damage.
References
- European Glaucoma Society (EGS): Terminology and Guidelines for Glaucoma. 5th Edition. EGS, 2021.
- Kanski, J. J.; Bowling, B.: Clinical Ophthalmology: A Systematic Approach. 8th Edition. Elsevier, 2015.
- Quigley, H. A.; Broman, A. T.: The number of people with glaucoma worldwide in 2010 and 2020. British Journal of Ophthalmology, 90(3):262–267, 2006.
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