Assessment of human vision for spatial patterns and its clinical applications

Abstract

Human vision for spatial pattern depends on information processes in the visual system for several basic physical variables, such as luminance, spatial frequency (or size), contrast and orientation, which determine characteristics of the pattern. Therefore, assessment of visual performance or visual quality needs to systematically measure the ability of the visual system in response to these variables. Because visual acuity only tests the resolution power under high luminance and high contrast, techniques capable of comprehensively assessing visual ability, such as the contrast sensitivity and contrast visual acuity tests, have been developed and widely applied in both eye research and clinical practice. Studies have shown that visual test under varied contrasts could be effectively used to ①diagnose many common eye diseases in the early stage and monitor effects of ophthalmic intervention and treatment; ②diagnose some specific visual disorders; and ③assess problems in daily performances which are associated with visual defects. Due to its highly standardization, and superior reliability, repeatability and accuracy in visual measurement,computerized technique will be the method for assessing visual performance in the future. Key words: Visual acuity; Contrast sensitivity; Computers