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fieldA locus on a data collection tool—usually a case report form—for recording or displaying a data element.
electromagnetic fieldAbbreviation: EMF
field of fixation
field of Forel
gradient-induced electric field
pulsing electromagnetic fieldAbbreviation: PEMF
The field is prepared by meticulously washing and scrubbing the patient on whom an operation will be performed with disinfectant solution. Sterile drapes and towels are placed over the patient to cover any unprepared skin or clothing with sterilized fabric. All surgical instruments that enter the operative theatre are cleansed according to decontamination and sterilization practices. Finally, all surgical personnel scrub for prescribed time periods with disinfectants before entering the operating room. They must wear sterile gloves, gowns, masks and shoe covers and replace these if any of them contact nonprepared items during surgery.
useful field of viewAbbreviation: UFOV
field of vision
binocular visual field An approximately circular zone of radius about 60º centred on the point of fixation (slightly larger in the lower part of the field) in which an object stimulates both retinas simultaneously. Beyond that area on each side, the visual field is monocular. See visual field.
field of excursion See field of fixation.
field of fixation The area in space over which an eye can fixate when the head remains stationary. The field of fixation is smaller than the field of vision. It extends to approximately 47º temporally, 45º nasally, 43º upward and 50º downward. Syn. field of excursion; motor field. See apparent field of view; real field of view; visual field.
field glasses See binoculars.
keyhole visual field A term used to describe a visual field defect in which there is a bilateral homonymous hemianopia with macular sparing. An occipital lobe lesion sparing the posterior tips of the occipital lobe usually causes this lesion.
field lens See eyepiece.
motor field See field of fixation.
receptive field The retinal area within which a light stimulus can produce a potential difference in a single cell. Retinal ganglion receptive fields are circular, often with a response different in the centre than in the periphery (also referred to as on-centre/off-centre or centre/surround organization). Ganglion cell receptive fields are very small in the macular region and large in the periphery of the retina. Receptive fields also exist in the lateral geniculate bodies where they are similar to those of the retina. In the visual cortex they have various shapes and sizes and may only respond to either a vertical bar or a black dot moving in a given direction and at a given speed, etc. Receptive fields reflect the interaction between excitation and inhibition between neighbouring neurons. The term can also describe the region of space that induces these neural responses (Fig. F2). See complex cell; hypercomplex cell; simple cell; lateral inhibition; summation.
field stop See diaphragm.
surrounding field That area of the field of view surrounding any object.
field of view The extent of an object plane seen through an optical instrument.
field of view, apparent Angle subtended by the exit port of a sighting instrument or an empty frame aperture at the centre of the entrance pupil of the eye. Syn. apparent peripheral field of view. Note: when referring to the apparent field of fixation, the reference point is the centre of rotation of the eye. Syn. apparent macular field of view (Fig. F3). See field of fixation.
field of view, real Angle subtended by the effective diameter of a lens at the point conjugate with the centre of the entrance pupil of the eye. Syn. real peripheral field of view; true field of view. Note: when referring to the real field of fixation, the reference point is the centre of rotation of the eye. Syn. real macular field of view (Fig. F3). See jack-in-the-box phenomenon.
field of vision See visual field.
visual field (VF) The extent of space in which objects are visible to an eye in a given position. The extent of the visual field tends to diminish with age. The visual field can be measured either monocularly or binocularly. In the horizontal plane meridian the visual field extends to nearly 190º with both eyes open, the area seen binocularly, that is the region where both eyes can see the simulus is about 120º, and the area seen by one eye only is about 154º. Syn. field of vision. See binocular visual field; kinetic perimetry; static perimetry; confrontation test; island of vision.
visual field expander An optical system designed to enlarge the field of vision. The most common types are reverse telescopes (e.g. looking through the objective of a galilean telescope), which minify objects being viewed but present more information by means of the enlarged visual field. They are usually of low power because of the reduction in visual acuity induced by the minification of the image. Prisms can also be used to expand the visual field. These systems are used mainly to improve mobility in patients with glaucoma and retinitis pigmentosa who have constricted visual fields or tunnel vision.
|Table F2 Average extent of the normal visual field (in degrees) of one eye of a young adult looking in the straight-ahead position, and measured with a white target subtending 1.0º under normal room illumination|
|down and temporally||88º|
|down and nasally||54º|
|up and nasally||56º|
|up and temporally||64º|
Patient discussion about field
Q. is there like a big break through in the field of autism therapy and approaching?
Q. My mother works in the medical field. I don’t want to discuss with my parents.I would appreciate your answer. I have some of the symptoms of ADHD for the past recent months. I am aware of the symptoms and now I feel the symptoms in me. People only notice these things as funny little quirks but this affects me severely. My mother works in the medical field. I don’t want to discuss with my parents. I would appreciate your answer.