An Innovative Media for Testing Visual Acuity

Peeraya Sripian, Teerapong Boonlar, Thaweesak Yingthavornsuk

Abstract


The visual acuity test is a routine part of an eye examination or general physical examination, particularly if there is a change in vision or a problem with vision. In most places, the Snellen chart is used to test visual acuity in humans. The Snellen chart relies on viewing the letters or symbols from a certain distance, usually 20 feet away. Human visual acuity is then determined by the smallest letter on the chart he/she is able to identify from that viewing distance. This testing method requires a room with enough viewing distance. With the advent of new technology, computerized visual acuity testing has been proposed and used in some clinical applications. The researchers propose an innovative media to measure visual acuity in human. A hybrid image is an image that changes its meaning according to the viewing distance. It is an image composed of two different spatial frequencies; high and low spatial frequency. Based on the contrast sensitivity function, the best viewing spatial frequency is changed by the viewing distance. With this assumption, we propose the use of hybrid image as a tool to test human visual acuity. From the experiment, it was found that the hybrid images can discriminate between patients with vision problems and patients with normal vision, and that the difference detected is statistically significant.

Keywords


Visual acuity measurement, Hybrid image, Computational visual illusion, Spatial frequency, Visual perception

Full Text:

PDF

References


Oliva, A., Torralba, A., and Schyns, P. G. Hybrid images. ACM Transactions on Graphics (TOG). vol. 25. 2006; 527 - 532.

Campbell, F. W., and Robson, J. Application of Fourier analysis to the visibility of gratings. The Journal of physiology. vol. 197. 1968; 551 - 566.

Schyns, P. G., and Oliva, A. Dr. Angry and Mr. Smile. When categorization flexibly modifies the perception of faces in rapid visual presentations. Cognition. vol. 69. 1999; 243 - 265.

Oliva, A., and Schyns, P. G. Coarse blobs or fine edges? Evidence that information diagnosticity changes the perception of complex visual stimuli. Cognitive psychology. vol. 34. 1997; 72 - 107.

Navon, D. Forest before trees: The precedence of global features in visual perception. Cognitive psychology. vol. 9. 1977; 353 - 383.

Hughes, H. C., Nozawa, G., and Kitterle, F. Global precedence, spatial frequency channels, and the statistics of natural images. Journal of cognitive neuroscience. vol. 8. 1996; 197 - 230.

Lindeberg, T. Detecting salient blob- like image structures and their scales with a scale-space primal sketch: a method for focus-of-attention. International Journal of Computer Vision. vol. 11. 1993; 283 - 318.

Parker, D. M., Lishman, J. R., and Hughes, J. Temporal integration of spatially filtered visual images. Perception. vol. 21. 1992; 147 - 160.

Sripian, P., and Yamaguchi, Y. Shape-free hybrid image. in Proceedings of the Symposium on Non-Photorealistic Animation and Rendering, Eurographics Association. 2012.

Snellen, H. Probebuchstaben zur Bestimmung der Sehschärfe. Cited from Duke-Elder. System of Ophthalmology, London. vol. 55. 1962; 371.

McGraw, P., Winn, B., and Whitaker, D. Reliability of the Snellen chart. BMJ: British Medical Journal. vol. 310. 1995; 1481.

Flom, M. C., Weymouth, F. W., and Kahneman, D. Visual resolution and contour interaction. JOSA. vol. 53. 1963; 1026 - 1032.

Guide, M. U. s. The mathworks. Inc., Natick, MA 5. 1998; 333.