Method for performing a contrast vision test
First Claim
1. A contrast vision test method for determining a contrast sensitivity function of a subject, said method comprising the steps of:
- (a) displaying visually to the subject, under a specified ambient viewing condition, a sinusoidal grating pattern, said grating pattern having a first axis, a second axis, a spatial frequency and a contrast, said spatial frequency changing continuously along said first axis, said contrast changing continuously along said second axis, said second axis being perpendicular to said first axis;
(b) determining, based on a response of the subject to viewing said grating pattern under said ambient viewing condition of step (a), a visual contrast sensitivity curve of the subject which defines the ability of the subject to visually discern said grating pattern under said ambient viewing condition of step (a);
(c) repeating steps (a) and (b) at least once with each respective repetition being carried out under a different respective said ambient viewing condition to determine at least one respective additional visual contrast sensitivity curve of the subject, each respective said additional visual contrast sensitivity curve defining the ability of the subject to visually discern said grating pattern under a respective one of said different ambient viewing conditions, and(d) statistically determining a contrast sensitivity function of the subject based on said visual contrast sensitivity curve and said at least one additional visual contrast sensitivity curve.
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Abstract
The invention relates to a method for performing a contrast vision test on a subject in order to determine a contrast sensitivity function. According to said method, an image of a continuous sinusoidal grid is presented to the subject for viewing, the spatial frequency continuously changes in the direction of a first axis, and the contrast continuously changes in the direction of a second axis that extends perpendicular to the first axis. The subject'"'"'s contrast sensitivity function is defined by means of a curve that encloses an area of the sinusoidal grid in which the subject perceives the sinusoidal grid pattern during viewing.
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Citations
20 Claims
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1. A contrast vision test method for determining a contrast sensitivity function of a subject, said method comprising the steps of:
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(a) displaying visually to the subject, under a specified ambient viewing condition, a sinusoidal grating pattern, said grating pattern having a first axis, a second axis, a spatial frequency and a contrast, said spatial frequency changing continuously along said first axis, said contrast changing continuously along said second axis, said second axis being perpendicular to said first axis; (b) determining, based on a response of the subject to viewing said grating pattern under said ambient viewing condition of step (a), a visual contrast sensitivity curve of the subject which defines the ability of the subject to visually discern said grating pattern under said ambient viewing condition of step (a); (c) repeating steps (a) and (b) at least once with each respective repetition being carried out under a different respective said ambient viewing condition to determine at least one respective additional visual contrast sensitivity curve of the subject, each respective said additional visual contrast sensitivity curve defining the ability of the subject to visually discern said grating pattern under a respective one of said different ambient viewing conditions, and (d) statistically determining a contrast sensitivity function of the subject based on said visual contrast sensitivity curve and said at least one additional visual contrast sensitivity curve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13)
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12. The apparatus as claimed in 11, further comprising an illumination apparatus arranged in the region of said display device such that said ambient viewing condition comprises a glare condition.
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14. A method for performing a contrast vision test on a subject in order to determine a contrast sensitivity function, said method comprising the steps of:
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(a) displaying visually to the subject a sinusoidal grating pattern, said grating pattern having a first axis, a second axis, a spatial frequency and a contrast, said spatial frequency changing continuously along said first axis, said contrast changing continuously along said second axis, said second axis being perpendicular to said first axis; (b) determining a visual contrast sensitivity curve of the subject based on a response of the subject to viewing said grating pattern; (c) assessing said curve based on a metric, said metric being a metric calculable using a calculation which includes multiplicatively;
(i) a maximum identified visual acuity of said curve on said first axis, (ii) a minimum identified contrast ratio of said curve on said second axis and (iii) a distance between a first point and a second point, said first point corresponding to a maximum contrast ratio and a minimum visual acuity, said second point corresponding to a point of intersection of said curve with a straight line extending between said first point and a corner point, said corner point corresponding to said minimum identified contrast ratio and said maximum identified visual acuity. - View Dependent Claims (15, 16, 17, 18, 20)
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19. The apparatus as claimed in 18, further comprising an illumination apparatus mounted for illuminating said display device such that said viewing condition comprises a glare condition.
Specification