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2 edition of Clinical application of contrast sensitivity in visual dysfunction found in the catalog.

Clinical application of contrast sensitivity in visual dysfunction

Maurice K. H. Yap

Clinical application of contrast sensitivity in visual dysfunction

an investigation into the use of contrast sensitivity testing as a clinical screening technique for visual abnormalities and a test of residual visual performance in low vision patients.

by Maurice K. H. Yap

  • 385 Want to read
  • 28 Currently reading

Published in Bradford .
Written in English


Edition Notes

Ph.D. thesis. Typescript.

SeriesTheses
ID Numbers
Open LibraryOL13979927M

Contrast sensitivity testing can also tell the clinician about the patient’s dominant eye and their overall quality of vision. Finally, contrast sensitivity testing helps clinicians to monitor changes in visual functioning over time. Slide 17 In general, if contrast sensitivity function is down, the patient will need more magnification. Contrast sensitivity is a measure of how faded or washed out an image can be before it becomes indistinguishable from a uniform field. It has been experimentally determined that the minimum discernible difference in gray scale level that the eye can detect is about 2% of full brightness.

The global or full-field electroretinogram (ERG) is a mass electrical response of the retina to photic stimulation. The ERG is a test used worldwide to assess the status of the retina in eye diseases in human patients and in laboratory animals used as models of retinal disease. The basic method of recording the electrical response known as the. The contrast required for the visual system to reach a certain threshold can be expressed as a sensitivity on a decibel (dB) scale (contrast sensitivity in dB = log 10 C). A plot of (contrast) sensitivity versus spatial frequency is called the spatial contrast sensitivity function (SCSF, or usually abbreviated to CSF).

Research: A listing of clinical research, papers, reports, and correspondence that uses, relies on, or otherwise refers to contrast sensitivity testing. The test offered on this website is a screening test only and cannot, by itself, be used to diagnose any condition. Contrast Sensitivity Function and Visual Performance Because the image of any object can be described as a set of spatial frequencies at various orientations, amplitudes, and phases (see Appendix C), there is the potential that an observers contrast sensitivity function can be used to predict visual performance with more complex visual material.


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Clinical application of contrast sensitivity in visual dysfunction by Maurice K. H. Yap Download PDF EPUB FB2

Medical Definition of Visual contrast sensitivity. Medical Author: William C. Shiel Jr., MD, FACP, FACR; Coronavirus COVID Latest News and Information. Visual contrast sensitivity: The ability to perceive differences between an object and its background. CONTINUE SCROLLING OR CLICK HERE FOR RELATED SLIDESHOW.

Visual threshold to determine the smallest difference in contrast between the visible and invisible is the threshold contrast, the reciprocal of which provides contrast sensitivity. Contrast Sensitivity Tests Contrast Sensitivity Tests 7 Which Luminance Level Should Be Used.

An international recommendation does not exist on the luminance level for contrast sensitivity testing, but there is a recommendation for visual acuity testing. It recommends a luminance level equal or higher than 85 candelas per square meter.

Abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia October Progress in Neuro-Psychopharmacology and Biological Psychiatry 30(7)   Medical Definition of Contrast sensitivity, visual. Contrast sensitivity, visual: The ability to perceive differences between an object and its background.

SLIDESHOW Pink Eye (Conjunctivitis) Symptoms, Causes, Treatments See Slideshow. Health Solutions From Our Sponsors. Peripheral color contrast. A new screening test for preglaucomatous visual loss. Invest Ophthalmol Vis Sci. Sep; 32 (10)– Verbaken J.

Role of the contrast sensitivity function in clinical practice. Am J Optom Physiol Opt. Apr; 64 (4)– Ginsburg AP. A Cited by:   Contrast sensitivity was also determined through the telescopic low-vision aids of selected patients.

In general, the patients have a substantial loss of contrast sensitivity for all spatial frequencies.

The preferred eye of these patients appeared to be related to the peak of the CSF more so than to the Snellen visual or resolution by: Contrast sensitivity testing with sine-wave or square-wave gratings may be a useful adjunct in the evaluation of vision loss. 17,18 Conventional visual acuity measures spatial resolution at high contrast, while contrast sensitivity testing assesses spatial resolution when contrast varies.

In one variation of the test, the patient is asked to identify in which direction the gratings, which span.

INTRODUCTION. Visual acuity (VA) is the conventional and standard test of visual function in patients with cataracts. However, some patients retain relatively good VA, yet complain of poor vision. 1 – 3 In these patients, other tests of visual function such as contrast sensitivity (CS) should be evaluated.

4 – 7 Contrast sensitivity measures visual performance under real-life conditions. Ophthalmology Jan;95(1) Eeffectof visual blur on contrast sensitivity. Clinical implication Marmor MF, Gawande A Age: There occurs a definite decrease in contrast sensitivity with increasing age.

The pathogenesis of this decline in vision is likely involves changes in the spherical aberration of the crystalline lens Luminance and contrast. Whatever the test distance, the chart must be adequately illuminated and of high contrast.

Illumination standards vary from cd/m 2 in the USA to cd/m 2 in Germany. Increasing chart luminance improves visual acuity in normal subjects, but reaches a plateau at about cd/m 2.

12 Various types of visual dysfunction can change the effects of luminance on acuity. contrast thresholds, a reciprocal measure (1/threshold), termed the contrast sensitivity score, is computed.

Measures of visual contrast sensitivity, rather than measures of refractory visual acuity, have been presented as better appraisals of visual dysfunction resulting.

Vision Perception and Cognition, Fourth Edition is a concisely structured text that expertly addresses clinical reasoning and decision making for the entire evaluation and treatment process of the adult with acquired brain injury.

Provided are theoretical information, guidelines for both static and dynamic assessment, information on specific standardized evaluations, guidelines for adaptive 5/5(1). Luminance and contrast. Whatever the test distance, the chart must be adequately illuminated and of high contrast.

Illumination standards vary from cd/m 2 in the USA to cd/m 2 in Germany. Increasing chart luminance improves visual acuity in normal subjects, but reaches a plateau at about cd/m 2. 12 Various types of visual dysfunction can change the effects of luminance on acuity.

Age-adjusted visual contrast sensitivity (VCS) was significantly lower and the presence of PEAS-associated symptoms was much higher in the estuary cohort (n = 77) than in combined-control cohorts (n = 87), one without exposure to bodies of water (n = 53) and one with exposure to marine waters (n = 34).

contrast sensitivity and low contrast letter acuity view these tests as complementary and in the final analysis each in its ownwayattempts to measure 'sensitivity to contrast' Ona practicallevel, owingto generalfamiliarity withthenatureof the task, letter contrast sensitivity testing usually proceeds uneventfully and without the need for Cited by:   Evaluate visual outcomes and contrast sensitivity for subjects undergoing bilateral myopic LASIK procedure using the kHz WaveLight® FS Femtosecond Laser and the WaveLight® Allegretto Wave® Eye-Q Laser.

The use of advanced technology may decrease the loss of contrast sensitivity and improvement of postoperative visual acuity results. Ophthalmology Jan;95(1) Eeffectof visual blur on contrast sensitivity. Clinical implication Marmor MF, Gawande A Age: There occurs a definite decrease in contrast sensitivity with increasing age.

The pathogenesis of this decline in vision is likely involves changes in the spherical aberration of the crystalline lens. Biological contrast sensitivity. According to Campbell and Robson (), the human contrast sensitivity function shows a typical band-pass filter shape peaking at around 4 cycles per degree with sensitivity dropping off either side of the peak.

This finding has led many to claim that the human visual system is most sensitive in detecting contrast differences occurring at 4 cycles per degree. Medical Research Archives, Vol.

5, Issue 5, May Pediatrics Norms for Visual Contrast Sensitivity Using an APT VCS Tester Copyright KEI Journals. Visual contrast sensitivity is a measure of the ability of the visual system to distinguish objects from the background.

Tests usually involve the presentation of letters or digits that are adjusted to become increasingly similar in brightness to the background until they can no longer be seen (Fig. ).Alternatively, gratings of parallel bars with different spatial frequencies are sometimes.Evaluation of contrast sensitivity and other visual function outcomes in neovascular age-related macular degeneration patients after treatment switch to aflibercept from ranibizumab Donald R Nixon, Nicholas AP Flinn Trimed Eye Center, Barrie, ON, Canada Purpose: This study evaluated visual function and anatomic and vision-related quality-of-life outcomes in recalcitrant neovascular age-related Cited by: 1.Evaluation of contrast sensitivity and other visual function outcomes in diabetic macular edema patients following treatment switch to aflibercept from ranibizumab Donald R Nixon, Nicholas AP Flinn Trimed Eye Center, Barrie, ON, Canada Purpose: This study aims to investigate changes in contrast sensitivity (CS), visual acuity (VA), central retinal thickness (CRT), and vision-related quality of Cited by: 4.