Your brain actively edits out your nose from your vision
In short: You can see your nose right now, yet you don't notice it. This isn't a trick of the light; it is a sophisticated feat of neural processing. While your eyes capture a vast spatial array, your brain filters the data to prioritize what matters for navigation and interaction.
The human visual field is defined as the portion of space visible during steady fixation in one direction. In a single eye (monocular vision), this extends approximately 60 degrees nasally and 107 degrees temporally from the vertical meridian, reaching about 70 degrees above and 80 degrees below the horizontal meridian. When both eyes work together (binocular vision), these fields superimpose to create a wider spatial array of visual sensations.
Because the nose is situated within the field of view of both eyes, it should technically be visible at all times. Nevertheless, because the brain performs subsequent analysis, this occurs unperceptibly throughout typical sight activities. This highlights the distinction between 'field of view'—the raw area captured by the organ—and the 'visual field,' which is often understood as a perceptual concept or the functional capacity recorded through perimetry.
Clinically, doctors map these fields to identify specific pathologies. For example, glaucoma typically causes peripheral field defects due to damage to the retinal nerve fiber layer, while macular degeneration affects the central 10 to 17 degrees of diameter responsible for high-resolution tasks like reading. By identifying distinct patterns—such as 'Bjerrum's area' (10°-20° from fixation) or 'bitemporal hemianopia' caused by chiasm lesions—neurologists can pinpoint exactly where a visual pathway is failing.
Testing these fields involves various methods, ranging from automated perimeters that flash light spots to 'confrontational field testing,' where a practitioner holds up fingers for the patient to count. These tools allow experts to measure the threshold of sensitivity and detect scotomas (blind spots) or generalized depressions in vision.
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Sources
- Summary by Intellect · source: Visual field
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