To determine if patients with unilateral cataract experience the Pulfrich effect and to quantify the magnitude of this effect with different grades of cataract.

To determine if the perception of the Pulfrich effect is dependent on the time duration after the cataract surgery.

To determine the relative impact of luminance difference, pupillary size and interocular blur difference in producing the Pulfrich effect in patients with unilteral cataract.