pe·rim·e·try (p -r m -tr )n. The determination of the limits of the visual field. |
perimetry
[pərim′ətrē]
the determination and mapping of the limits of the visual field.
perimetry [pĕ-rim´ĕ-tre]
determination of the extent of the peripheral visual field. adj., adj perimet´ric.
perimetry
The determination of the extent of the visual field, usually for the purpose of detecting anomalies in the visual pathway. See glaucoma; lens rim artifact; perimeter.
frequency doubling p . (FDP) A method of testing the visual field based on the frequency doubling illusion and thus assessing the functional integrity of the large-diameter retinal ganglion M cells, which are very susceptible to early glaucomatous damage. A commercial version of this method, which provides rapid and efficient visual field testing, is available (Humphrey Instruments/Welch Allyn). It is a computerized perimeter in which the stimulus display consists of a low spatial frequency (0.25 c/deg) sinusoidal grating which flickers in a counterphase fashion (i.e. light bars become dark and vice versa) at a rate of 25 Hz. The grating is presented in many locations throughout the visual field and the patient's task is to detect it. See open-angle glaucoma; frequency doubling illusion.
kinetic perimetry Measurement of the visual field with a moving target of fixed luminance.
short wavelength automated p . (SWAP) A valuable procedure for detecting and monitoring visual defects in patients with ocular hypertension and patients with early glaucomatous visual field losses. It uses a blue stimulus on a yellow background, as may be arranged in an automated perimeter. It is a more sensitive and efficient method of detecting and monitoring early visual field losses than standard white-on-white automated perimetry (white stimulus on a white background). See open-angle glaucoma.
static perimetry Measurement of the visual field with a target that can be varied in dimension and luminance. The target can be presented in any part of the visual field.
frequency doubling p . (FDP) A method of testing the visual field based on the frequency doubling illusion and thus assessing the functional integrity of the large-diameter retinal ganglion M cells, which are very susceptible to early glaucomatous damage. A commercial version of this method, which provides rapid and efficient visual field testing, is available (Humphrey Instruments/Welch Allyn). It is a computerized perimeter in which the stimulus display consists of a low spatial frequency (0.25 c/deg) sinusoidal grating which flickers in a counterphase fashion (i.e. light bars become dark and vice versa) at a rate of 25 Hz. The grating is presented in many locations throughout the visual field and the patient's task is to detect it. See open-angle glaucoma; frequency doubling illusion.
kinetic perimetry Measurement of the visual field with a moving target of fixed luminance.
short wavelength automated p . (SWAP) A valuable procedure for detecting and monitoring visual defects in patients with ocular hypertension and patients with early glaucomatous visual field losses. It uses a blue stimulus on a yellow background, as may be arranged in an automated perimeter. It is a more sensitive and efficient method of detecting and monitoring early visual field losses than standard white-on-white automated perimetry (white stimulus on a white background). See open-angle glaucoma.
static perimetry Measurement of the visual field with a target that can be varied in dimension and luminance. The target can be presented in any part of the visual field.
perimetry
Ophthalmology A test in which a topographic 'map' is created of the visual field, to diagnose and evaluate diseases of optic nerve, retina, and neuroophthalmic Goldman perimetry; uses both stationary–static
light sources of increasing intensity and moving light sources to delineate the visual field, defects of which can be either central or peripheral
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