The equivalent concept for optical instruments and sensors is the field of view (FOV).
In optometry and ophthalmology 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 or a reduction in sensitivity (increase in threshold).
The normal human visual field extends to approximately 60 degrees nasally (toward the nose, or inward) from the vertical meridian in each eye, to 100 degrees temporalily (away from the nose, or outwards) from the vertical meridian, and approximately 60 degrees above and 75 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 17 degrees diameter of the visual field; the fovea to the central 5.2 degrees, and the foveola to 1–1.2 degrees diameter.
Measuring the visual field
The visual field is measured by perimetry. This may be kinetic, where spots of light are shown on the white interior of a half sphere and moved inwards until the observer sees them, or static, where the light spots are flashed at varying intensities at fixed locations in the sphere until detected by the subject. Commonly used perimeters are the automated Humphrey Field Analyzer, the Heidelberg Edge Perimeter, or the Oculus.
Another method is to use a campimeter, a small device with a flat screen designed to measure the central visual field.
Light spot patterns testing the central 24 degrees or 30 degrees of the visual field, are most commonly used. Most perimeters are also capable of testing the full field of vision.
Another method is for the practitioner to hold up 1,2, or 5 fingers in the four quadrants and center of a patient's visual field (with the other eye covered). If the patient is able to report the number of fingers properly as compared with the visual field of the practitioner, the normal result is recorded as "full to finger counting" (often abbreviated FTFC). The blind spot can also be assessed via holding a small red object between the practitioner and the patient. By comparing when the red object disappears for the practitioner, a patient's abnormally large blind spot can be identified. There are many variants of this type of exam (e.g. wiggling fingers at visual periphery in cardinal axes).
Visual field loss
|This section may need to be rewritten entirely to comply with Wikipedia's quality standards, as this categorization is not generally agreed upon (e.g. heteronymous hemianopia is missing). (August 2015)|
- Altitudinal field defects, loss of vision above or below the horizontal – associated with ocular abnormalities
- Bitemporal hemianopia, loss of vision at the sides (see below)
- Central scotoma, loss of central vision
- Homonymous hemianopia, loss at one side of the visual field for both eyes – defect located behind optic chiasm (see below)
The good vision island
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The visual field is uneven. It is not uniform and has its maximum definition in its central part.
Harry Moss Traquair describes in 1927 that our visual field as "an island of vision or hill of vision surrounded by a sea of blindness". The 'island of vision' corresponds to a sudden change of definition we have. Its empirical elliptical limits in the longest (horizontal) axis, are our Blind Spots.
Kim Lloveras i Montserrat, argues that in the Romanesque age, people were aware of the particularities of our blinds spots as horizontal limits of the central good vision. Further, they know that more than a change in definition there is a strong change of perception of space. The observer feels inside the central area and understands their borders as 'their enveloping', making them a very helpful principle for architectural design. The exhibit La experiencia del Espacio Personal at the Barcelona School of Architecture explored this phenomenon, using a large ellipse (TK), which is 3.10 meters tall (twice the height of a person) and has a major axis of 3.94, located 6.38 m from the observer (these dimensions are very similar to those proposed by Traquair for the limits of the "visual island").
- Smythies J (1996). "A note on the concept of the visual field in neurology, psychology, and visual neuroscience". Perception 25 (3): 369–71. doi:10.1068/p250369. PMID 8804101.
- Robert H. Spector (1990). Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.
- Strasburger, H.; Rentschler, I.; Jüttner, M. (2011). "Peripheral vision and pattern recognition: a review". Journal of Vision 11 (5): 1–82.
- Polyak, S. L. (1941). The Retina. The University of Chicago Press.
- Jay WM (1981). "Visual field defects". American Family Physician 24 (2): 138–42. PMID 7258077.
- Traquair,Harry Moss. An Introduction to clinical perimetry. London, Henry Kimpton,1927,pp.264.
- MedlinePlus Encyclopedia Visual Field
- Patient Plus
- Quadrantanopsia Visual Fields Teaching Case from MedPix
- Strasburger, Hans; Rentschler, Ingo; Jüttner, Martin (2011). Peripheral vision and pattern recognition: a review. Journal of Vision, 11(5):13, 1–82.
- Software for visual psychophysics; VisionScience.com