Contrast Sensitivity FunctionDownload from Apple Store
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ClinicCSF is an application developed for measuring the Contrast Sensitivity Function. The App has been validated through two research studies that report the validity and reproducibility.
Contrast Sensitivity is a psychophysical measurement of Visual Function. It is defined as the inverse of the minimum quantity of contrast that an observer would be able to detect. A general definition of spatial contrast is that it is a physical dimension referring to the light-dark transition of a border or an edge of an image that delineates the existence of a pattern or object. Contrast is defined as the ratio of the difference in the luminance of these two adjacent areas to the lower or higher of these luminance values (Owsley, 2003).
There are two common ways in vision for expressing contrast. These ways are associated with the different kinds of Clinical Test. The Michelson contrast usually applies to periodic patterns such as Sinusoidal or Square Grattings. At the rightimage we show a Clinic CSF stimulus calculated by Michelson Contrast. In other way, no periodical patterns as optotypes are presented on spatially extended white backgrounds, contrast is tipically defined as luminance of the background (Lmax) minus of the luminance of the letter (Lmin), divided by the luminance of the background (left Image). For measuring Visual Acuity at Low Contrast, please visit VisionC: ETDRS chart and SLOAN letters .
- Sinusoidal Grattings as stimulus.
- 4 spatial frequencies (3,6,12,18 c.p.d).
- Sound Feedback after pressing a button.
- Comparison of results with normal age ranges.
- A Fixation Mask to recognize where the stimulus is included to make easy its localization on the screen by the patient.
- Results showed on a Figure with normal values for different ages.
- Stimulus generated after calibration with Spyder4Elite on IPad 2 and IPad Retina.
The ClinicCSF can be used to measure the visual performance with different optical compensations (spectacles, contact lenses, surgery procedures) or for evaluating any disease that affects to the Visual Pathways. The patient should wear the best correction with spectacles or monofocal contact lenses (for evaluating the optical pathways).
- The test is conducted in monocular vision, with each one of the eyes.
- The distance between the test and the patient should be 2 m.
- The Optometrist should explain the procedure to the patient, El Optometrista debe explicar el procedimiento del test al paciente, haciendo hincapié en que en ciertas ocasiones es posible que no lo perciba puesto que vamos a examinar los límites de su visión.
- The Optometrist should press the button indicating the response of the patient. If the patient refers not seeing, Optometrist should press any of button alleatory.
- Test automatically calculates the next contrast and spatial frequency to present. Optometrist should only worry about motivate patient to blink after each response until the test is completed and the results window is showed.
- There are no scheduled updates for this app.