Tunnel vision is the loss of

peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in th ...

with retention of central vision, resulting in a constricted circular

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

-like

field of vision The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...

Causes

Tunnel vision can be caused by:

Eyeglass users

Eyeglass Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples ...

users experience tunnel vision to varying degrees due to the

corrective lens A corrective lens is a lens (i.e. a transmissive optical device) that is typically worn in front of the eye to improve daily vision. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. G ...

only providing a small area of proper focus, with the rest of the field of view beyond the lenses being unfocused and blurry. Where a naturally sighted person only needs to move their eyes to see an object far to the side or far down, the eyeglass wearer may need to move their whole head to point the eyeglasses towards the target object. The eyeglass frame also blocks the view of the world with a thin opaque boundary separating the lens area from the rest of the field of view. The eyeglass frame is capable of obscuring small objects and details in the peripheral field.

Mask, goggle, and helmet users

Activities which require a protective mask, safety goggles, or fully enclosing protective helmet can also result in an experience approximating tunnel vision. Underwater

diving mask Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), ...

s using a single flat transparent lens usually have the lens surface several centimeters from the eyes. The lens is typically enclosed with an opaque black rubber sealing shell to keep out water. For this type of mask the peripheral field of the diver is extremely limited. Generally, the peripheral field of a diving mask is improved if the lenses are as close to the eye as possible, or if the lenses are large, multi-window, or is a curved wrap-around design. Protective helmets such as a welding helmet restrict vision to an extremely small slot or hole, with no peripheral perception at all. This is done out of necessity so that

ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

emitted from the

welding arc Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as braz ...

does not damage the welder's eyes due to reflections off shiny objects in the peripheral field.

Optical instruments

Binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...

s, and

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisi ...

s induce an experience of extreme tunnel vision due to the design of the optical components. A wide field microscope or telescope generally requires much larger diameter and thicker lenses, or complex parabolic mirror assemblies, either of which results in significantly greater cost for construction of the optical device. Wide-field binoculars are possible, but require bulkier, heavier, and more complex eyepieces. The diameter of the objective lenses is unimportant for field of view. The widest-angle eyepieces used in telescopes are so large that two would not fit side-by-side for use in binoculars.

References

External links