에 의해 작성된 Nasanen
1. Letter contrast sensitivity function for various spatial frequencies can be measured using the same band-pass filtered letters as used in the visual field measurement.
2. The stimulus size increases towards larger eccentricities (eccentricity = sideward angular distance from the fixation point) for obtaining a roughly equal cortical representation as well as a roughly equal sensitivity across the visual field if the field is healthy.
3. ● Cortical Perimeter - by Nasanen and Raninen - is a software tool for the evaluation of contrast sensitivity of the visual field at very low cost using ordinary computer displays.
4. Vision is trained in defective visual field locations by measuring contrast sensitivity repeatedly for numerous times during weeks or months.
5. ● Further, with the ‘Training mode’, Cortical Perimeter can be used for training possible residual vision at defective visual field locations.
6. Large displays allow measurement of larger visual field areas.
7. The measurement can be done using different combinations of stimuli and tasks: Detection of static rings, Detection of flickering rings, Identification of static letters, or Identification of flickering letters.
8. Some scientific studies suggest that the function of peripheral vision at defective areas after cortical lesion can be improved by intensive training, at least in some cases.
9. With a 27-inch display and a viewing distance of 40 cm, the maximum field dimensions are 30 deg horizontally and 19 deg vertically.
10. ● In addition, it is possible to evaluate the ‘Letter Contrast Sensitivity Function’ (LCSF) of central vision.
11. ● If a sufficiently large display and short viewing distance (e.g., 27-inch viewed at a distance of 20 cm) is used, a full 30-deg-field can be measured.
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