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
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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