Contrast Sensitivity of Air-Breathing Nonprofessional Scuba Divers at a Depth of 40 Meters

1992 ◽  
Vol 75 (1) ◽  
pp. 275-283
Author(s):  
Nico A. M. Schellart
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Fresh Water ◽  
Test Pattern ◽  
Sine Wave ◽  
Air Breathing ◽  
Scuba Divers ◽  
Visual Contrast ◽  
Sine Wave Gratings ◽  
Visual Contrast Sensitivity

Photopic contrast sensitivity of air-breathing scuba divers was measured with a translucent test pattern at depths up to 40 m. The pattern was composed of sine wave gratings with spatial frequency and contrast changing logarithmically. The spatial transfer characteristics were measured at various depths under controlled optical conditions in seawater and in fresh water. Analysis indicates that the visual contrast sensitivity, and therefore probably also acuity, of sport divers is not affected up to depths of 40 m. This holds under ideal as well as poor diving conditions.

Low Spatial Frequency Contrast Sensitivity Deficits in Migraine are not Visual Pathway Selective

Cephalalgia ◽  
2009 ◽  
Vol 29 (5) ◽  
pp. 539-549 ◽  
Author(s):  
AM McKendrick ◽  
GP Sampson
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Parvocellular Pathway ◽  
Functional Deficits ◽  
Visual Contrast ◽  
Sensitivity Loss ◽  
Significant Difference ◽  
Pathway Function ◽  
Migraine Group ◽  
Visual Contrast Sensitivity

Some people who experience migraine demonstrate reduced visual contrast sensitivity that is measurable between migraines. Contrast sensitivity loss to low spatial frequency gratings has been previously attributed to possible impairment of magnocellular pathway function. This study measured contrast sensitivity using low spatial frequency targets (0.25–4 c/deg) where the adaptation aspects of the stimuli were designed to preferentially assess either magnocellular or parvocellular pathway function (steady and pulsed pedestal technique). Twelve people with migraine with measured visual field abnormalities and 17 controls participated. Subjects were tested foveally and at 10° eccentricity. Foveally, there was no significant difference in group mean contrast sensitivity. At 10°, the migraine group demonstrated reduced contrast sensitivity for both the stimuli designed to assess magnocellular and parvocellular function ( P < 0.05). The functional deficits measured in this study infer that abnormalities of the low spatial frequency sensitive channels of both pathways contribute to contrast sensitivity deficits in people with migraine.

scholarly journals Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

2005 ◽  
Vol 8 (2) ◽  
pp. 113-118
Author(s):  
Miguel A. García-Pérez
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Light Level ◽  
Sine Wave ◽  
Retinal Illuminance ◽  
Visual Functioning ◽  
Photopic Vision ◽  
Spatial Frequencies ◽  
Grating Acuity ◽  
Sine Wave Gratings

Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber's law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber's laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies.

scholarly journals Impacts of Mild and Moderate Acute Hypoxia on Visual Contrast Sensitivity

2021 ◽  
Author(s):  
Weiming Yan ◽  
Guanhua Zhao ◽  
Pan Long ◽  
Meizhu Chen ◽  
Zuoming Zhang ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Acute Hypoxia ◽  
Color Contrast ◽  
Blood Oxygen Saturation ◽  
Visual Contrast ◽  
Spatial Frequencies ◽  
Temporal Quadrant ◽  
Student’S T ◽  
Visual Contrast Sensitivity

Abstract Introduction: Acute hypoxia could hamper the visual performance during the aviation. In the study, we aimed to investigate the effects of acute hypoxia on the contrast sensitivity (CS) and the color contrast sensitivity (CCS).Methos: 12 healthy volunteers (aged 20-22 years old) were selected for CS and CCS examination at altitude of 300m, 3000m and 4500m by applying the hypobaric cabin to simulate acute hypoxia (3000m in height = mild hypoxia; 4500m = moderate hypoxia). All data were collected after the heart rate and the blood oxygen saturation became stable, and were analyzed by the paired student’s t-test. Results: The CS at the spatial frequency of 1.5 Cpd was significantly increased at the altitude of 3000m (P<0.05), while CS at the higher spatial frequencies was not significantly affected. The CS of 1.5 and 3.0 Cpd was increased at the altitude of 4500m (P<0.05), while the CS of higher spatial frequency did not change significantly. With the increased degree of hypoxia, the overall CCS was increased with a statistical difference at 4500m (P<0.05). The CCS of the temporal superior and inferior quadrants were significantly affected (P<0.05), while those in other quadrants were significantly changed. Conclusions: Mild and moderate acute hypoxia could affect the CS in the low spatial frequency. With the increased degree of acute hypoxia, CCS deteriorates with the temporal quadrant more vulnerable to be affected.

scholarly journals Visual Contrast Sensitivity in Early-Stage Parkinson's Disease

2016 ◽  
Vol 57 (13) ◽  
pp. 5696 ◽  
Author(s):  
Wendy Ming ◽  
Dimitrios J. Palidis ◽  
Miriam Spering ◽  
Martin J. McKeown
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Contrast Sensitivity ◽  
Early Stage ◽  
Visual Contrast ◽  
Visual Contrast Sensitivity

Light therapy increases visual contrast sensitivity in seasonal affective disorder

2004 ◽  
Vol 126 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Zoltán Szabó ◽  
Andrea Antal ◽  
Zsolt Tokaji ◽  
János Kálmán ◽  
Szabolcs Kéri ◽  
...  
Keyword(s):  
Affective Disorder ◽  
Contrast Sensitivity ◽  
Seasonal Affective Disorder ◽  
Light Therapy ◽  
Visual Contrast ◽  
Visual Contrast Sensitivity

The Dependence of Monocular Rivalry on Spatial Frequency

Perception ◽  
1973 ◽  
Vol 2 (2) ◽  
pp. 127-133 ◽  
Author(s):  
J Atkinson ◽  
F W Campbell ◽  
A Fiorentini ◽  
L Maffei
Keyword(s):  
Spatial Frequency ◽  
Sine Wave ◽  
Ambiguous Figures ◽  
Alternation Rate ◽  
Higher Harmonics ◽  
Square Wave ◽  
Sharp Edges ◽  
Harmonic Components ◽  
Sine Wave Gratings

The effect of change in spatial frequency on the alternation rate of two crossed gratings was measured. The rate was found to decrease with increase in spatial frequency, but to change only little with contrast. Low alternation rate was observed for crossed square-wave gratings compared to crossed sine-wave gratings; here the rate of rivalry is largely dependent upon the presence or absence of the first three harmonic components rather than the higher harmonics which contribute to the sharp edges of the square wave. The results are compared with those for some ambiguous figures.

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