Amblyopia is a disturbance of spatial or form vision that develops early in life, usually in association with strabismus, anisometropia, high refractive errors and so on. It was reported that the visual functions obtained from the foveal region of an amblyopic eye rresembled those obtained from the peripheral retina rather than central retina of a normal eye. We designed this experiment which examines the effects of diffusion blur on gration and Snellen acuity in normal and amblyopic eyes, using a liquid crystal window. We obtained the value of diffsuion blur in 26 amblyopic eyes and then compared the result with that of normal eyes. The diffusion blur had a strong negative effect on both the snellen and grating acuity but it had a more potent effect on gration acuity. Becauses there is a significant difference in the diffusion blur produced by an amblyopic eyes and a normal eye at the same vision, there is a difference between visual function of amblyopic eyes and that of normal central retina