Abstract
Cataract is one of the most typical age-related eye diseases. As the cataract progresses, the crystalline lens becomes hazier and the visual ability deteriorates. Since the main cause of visual impairment is light scattered by the hazy crystalline lens inside eyeball, both brighter environments and hazier lenses worsen visual ability. In this study, increase of contrast thresholds were measured for pseudo-cataract subjects (young subjects with foggy filters of known haze factor) when the intensity of scattering light was increased. The rate of increase was larger with higher haze factor of lens. We propose, as an easy method for assessing the degree of cataract, the haze estimation of crystalline lens using the obtained contrast threshold as a function of scattering light intensity.