Visual Fields

By: Carmen Willings
teachingvisuallyimpaired.com
​Updated June 13, 2025
The visual field refers to the entire area a person can see when looking straight ahead, including central and peripheral vision. This field is measured in degrees of angle.
  • A person with normal vision can typically see about 160–180 degrees horizontally (side to side), and about 120 degrees vertically (up and down).
  • The central one-third of the visual field is where both eyes overlap in vision.
  • Visual field loss can affect any area—central, peripheral, or both.
  • A person is considered to have low vision if the visual field in their better-seeing eye is 40 degrees or less, with severe impairment defined as 20 degrees or less.​​

Central Vision

Central vision—also called macular vision—is often referred to as the "what system." It is responsible for:
  • Sharp, detailed vision
  • Color perception
  • Reading and other critical visual tasks, both near and far
This is the part of vision typically improved by corrective lenses. However, if the macula is damaged or underdeveloped (as in cataracts or macular degeneration), glasses will not improve vision.
Common conditions affecting central vision:
  • Macular Degeneration
  • Cone Dystrophies
  • Central Scotomas
Note: A student with central vision loss may appear to see normally but struggle with reading or detailed tasks—even if they do not wear glasses.

Peripheral Vision

Peripheral vision is the "where system." It is important for:
  • Detecting movement
  • Navigating in dim lighting
  • Mobility and spatial awareness
Common conditions affecting peripheral vision:
  • Glaucoma
  • Retinitis Pigmentosa
  • Retinal Detachment
  • Chorioretinitis

​Combined Central and Peripheral Vision Loss

Some conditions affect both central and peripheral fields simultaneously. These include:
  • Coloboma
  • Optic Nerve Atrophy
  • Optic Nerve Hypoplasia
  • Septo-Optic Dysplasia
  • Hemianopsia
  • Stroke-related vision loss
  • Other optic nerve disorders

Types of Visual Field Loss

There are different types of visual field loss. 
  • Scotoma: A blind spot anywhere in the visual field
  • Hemianopsia: Loss of half the visual field in one or both eyes
  • Tunnel Vision: Loss of peripheral vision with retention of central vision
Note: Losing vision in one eye does not reduce vision by 50%. While the affected side loses visual input and depth perception is diminished, the unaffected eye still provides substantial central and peripheral vision.
It is possible to:
  • Have good central vision with limited peripheral vision
  • Have good peripheral vision with limited central vision​​

Eccentric Gaze

Students with scotomas (blind spots) may adopt an eccentric gaze. This means:
  • They may look slightly above, below, or to the side of an object to see it clearly.
  • This can appear as if they’re not looking directly at what they are trying to see, even though they are using their best remaining vision.
*Ward, Marjorie E., Foundations of Low Vision: Clinical and Functional Perspectives. AFB Press 2004. p. 73 
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