نتایج جستجو برای: contrast sensitivity functions

تعداد نتایج: 1162208  

Journal: :Vision Research 2002
David A Atchison Dion H Scott

We investigated the influence of the Stiles-Crawford effect (SCE) of the first kind on the contrast sensitivity function using the apodisation model of the SCE. The SCE was measured for the right eyes of two subjects using an increment threshold technique involving a two-channel Maxwellian-viewing system. Filters made of photographic film neutralised or doubled the SCE. Contrast sensitivities w...

2016
William H. Swanson Mitchell W. Dul Douglas G. Horner Victor E. Malinovsky

This data article contains data referenced in "Individual Differences in the Shape of the Nasal Visual Field" [1]. The data were gathered from volunteers free of eye disease ages 21-85 who were tested with Contrast Sensitivity Perimetry (CSP), which uses a stimulus resistant to effects of defocus and reduced retinal illumination. Some subjects were tested only once or a few times, and others we...

Journal: :Vision Research 2015
Abinaya Priya Venkataraman Simon Winter Peter Unsbo Linda Lundström

A prolonged exposure to foveal defocus is well known to affect the visual functions in the fovea. However, the effects of peripheral blur adaptation on foveal vision, or vice versa, are still unclear. In this study, we therefore examined the changes in contrast sensitivity function from baseline, following blur adaptation to small as well as laterally extended stimuli in four subjects. The smal...

Journal: :Vision Research 2008
Kara A. Stavros Lynne Kiorpes

We measured the developmental time course for temporal contrast sensitivity in macaque monkeys. The animals, aged 5 weeks to 4 years, detected an unpatterned field of light sinusoidally modulated over time at frequencies ranging from 1 to 40 Hz. Young infants showed reduced sensitivity for all frequencies, and a reduced range of detectable frequencies. Sensitivity to high and low frequencies de...

2015
Nadine Hollbach Christoph Tappeiner Anna Jazwinska Volker Enzmann Markus Tschopp

Sensitivity to spatial and temporal patterns is a fundamental aspect of vision. Herein, we investigated this sensitivity in adult zebrafish for a wide range of spatial (0.014 to 0.511 cycles/degree [c/d]) and temporal frequencies (0.025 to 6 cycles/s) to better understand their visual system. Measurements were performed at photopic (1.8 log cd m(-2)) and scotopic (-4.5 log cd m(-2)) light level...

Journal: :Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians 2010
Cynthia L Clark Joseph L Hardy Vicki J Volbrecht John S Werner

BACKGROUND Our lab has previously demonstrated losses in contrast sensitivity to low spatial frequencies under scotopic conditions with older adults. It is not clear, however, whether the temporal frequency of a stimulus alters the relation between age and the spatial contrast sensitivity function (sCSF) under scotopic conditions. METHODS A maximum-likelihood, two-alternative, temporal forced...

Journal: :Vision Research 1996
Julian J. Nicholas Charles A. Heywood Alan Cowey

The effects of early monocular form deprivation on the developing mammalian visual system, and the anatomical and physiological consequences of early monocular enucleation, suggest that the remaining eye of human subjects who had the other eye removed early during development might be capable of supernormal performance. To test this inference, the achromatic contrast sensitivity of the remainin...

Journal: :Journal of the Optical Society of America. A, Optics, image science, and vision 2000
P M Pearson W H Swanson

A model of foveal achromatic and chromatic sensitivity [Vision Res. 36, 1597 (1996)] was extended to the peripheral visual field. Threshold-versus-illuminance functions were analyzed to determine effects of eccentricity on absolute thresholds and gain constants of chromatic and luminance mechanisms. The resulting peripheral model successfully predicted peripheral contrast sensitivity as a funct...

Journal: :Investigative ophthalmology & visual science 1977
D M Levi R S Harwerth

Contrast sensitivity functions for sinusoidal gratings of different spatial frequencies and stimulus durations have been determined for both eyes of amblyopic subjects. For both long and short stimulus durations, the entire contrast sensitivity function of the amblyopic eyes is lower than that of the nonamblyopic eyes. When the gratings were flickered at 10 Hz, the sensitivity for pattern and f...

Journal: :بینا 0
محمدرضا جعفری نسب mr jafarinasab تهران- پاسداران- بوستان نهم- بیمارستان لبافی نژاد- مرکز تحقیقات چشم احمدرضا باقی ar baghi تهران- پاسداران- بوستان نهم- بیمارستان لبافی نژاد- مرکز تحقیقات چشم فرید کریمیان f karimian تهران- پاسداران- بوستان نهم- بیمارستان لبافی نژاد- مرکز تحقیقات چشم مهدی یاسری m yaseri تهران- پاسداران- بوستان نهم- بیمارستان لبافی نژاد- مرکز تحقیقات چشم

purpose: to compare tecnis z9000 and acrysof iq aspheric intraocular lenses (iols) regarding spherical aberration and contrast sensitivity. methods: thirty-four eyes of 34 patients undergoing phacoemulsification cataract surgery were randomly assigned to implantation of tecnis or iq iols. three months postoperatively, best-corrected visual acuity (bcva), spherical aberration (with 4 and 6 mm pu...

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