The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments" (J. Smythies [1]), while field of view "refers to the physical objects and light sources in the external world that impinge the retina". In other words, field of view is everything that (at a given time) causes light to fall onto the retina. This input is processed by the visual system, which computes the visual field as the output. This article or section does not adequately cite its references or sources. ... The field of view is the part of the observable world that is seen at any given moment. ... This article is about the psychological process of introspecting. ... Human eye cross-sectional view. ... The visual system is the part of the nervous system which allows organisms to see. ...

The term is often used in optometry and ophthalmology, where a visual field test is used to determine whether the visual field is affected by diseases that cause local scotoma or a more extensive loss of vision. Optometry (Greek: optos meaning seen or visible and metria meaning measurement) is the health care profession concerned with examination, diagnosis, and treatment of the eyes and related structures and with determination and correction of vision problems using lenses and other optical aids [1]. An optical refractor (also called a phoropter... This does not adequately cite its references or sources. ... A visual field test is an examination that may be performed to analyze a patients visual field. ... The word scotoma is derived from the Greek word for darkness. ... Visual loss results in the absence of vision where it existed before, which can happen either acutely or over a long period of time. ...

Normal limits

The normal human visual field extends to approximately 35 degrees nasally (toward the nose, or inward) in each eye, to 90 degrees temporally (away from the nose, or outwards), and approximately 50 degrees above and below the horizontal meridian. In the United Kingdom, the minimum field requirement for driving is 60 degrees either side of the vertical meridian, and 20 degrees above and below horizontal. The macula corresponds to the central 13 degrees of the visual field; the fovea to the central 3 degrees. Human eye cross-sectional view. ... The fovea, a part of the eye, is a spot located in the center of the macula. ...

Measuring the visual field

The visual field is measured by perimetry. This may be dynamic (eg. Goldmann), where points of light are moved inwards until the observer sees them, or static, where points of light are flashed onto a white screen and the observer is asked to press a button if he or she sees it. The commonest perimetry used is the automated Humphrey (static) perimeter. It usually tests either the central 24 degrees or 30 degrees of the visual field. As can be noted from the above legal requirement in the UK (60 degrees to the central vertical) the tests most often performed by Opthalmologists (or usually their assistants)do NOT test for peripheral defects. There are machines capable of doing FULL FIELD tests (Medmont). This machine is popular with Optometrists in Australia whilst the Humphrey and Goldman seem favoured by Opthalmologists. Perimetry is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. ...

Still, most health care professionals regardless of their profession usually only perform a central screening test. Patients should ask for a full field test as peripheral defects could be miss with a central test and the patient falsely reassured they have no defect. Studies have also shown that a flickering focused target image produces the most reliable results but many professionals and/or their assistants seem unaware of this and test without a corrective lens with non-flickering targets.

Visual field loss

Visual field loss may occur due to disease or disorders of the eye, optic nerve, or brain. In humans, confrontational testing and other forms of perimetry are used to detect and measure visual field loss. Different neurological difficulties cause characteristic forms of visual disturbances, including hemianopsias (shown below without macular sparing), quadrantanopsia, and others. A human eye. ... This article is about the anatomical structure. ... In animals the brain, or encephalon (Greek for in the head), is the control center of the central nervous system, responsible for thought. ... Perimetry is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. ... Hemianopsia is the loss of half the vision in both eyes. ... Human eye cross-sectional view. ...

Paris as seen with full visual fields

Paris as seen with bitemporal hemianopsia

Paris as seen with binasal hemianopsia

Paris as seen with left homonymous hemianopsia

Paris as seen with right homonymous hemianopsia

Image File history File links Download high resolution version (1183x595, 1238 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 1238 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 703 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 703 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Paris as seen with full visual fields Paris as seen with bitemporal hemianopsia Bitemporal hemianopsia is the medical description of a type of partial blindness that is associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary... Image File history File links Download high resolution version (1183x595, 730 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 730 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Binasal hemianopsia is the medical description of a type of partial blindness that is associated with certain lesions of the eye, and of the central nervous system, such as congenital hydrocephlus. ... Image File history File links Download high resolution version (1183x595, 691 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 691 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Homonymous hemianopsia is a medical term for a type of partial blindness resulting in a loss of vision in the same visual field of both eyes. ... Image File history File links Download high resolution version (1183x595, 713 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (1183x595, 713 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Homonymous hemianopsia is a medical term for a type of partial blindness resulting in a loss of vision in the same visual field of both eyes. ...

External links

• MedlinePlus Encyclopedia 003879
• Diagram linking defects to damage, at Brown
• University of Toronto
• Patient Plus
• IXMUS Color Field Test Blue-Yellow and Blue-Red Color Visual Field Testing for Macular Degeneration and Optic Nerve Disease