Patients with "early" posterior subcapsular (PSC) cataracts often complain of severe visual impairment, despite maintenance of relatively good Snellen acuity. The Arden grating test of contrast sensitivity provides a simple method of evaluating visual function in a manner more nearly approximating the real visual world. This test often reveals profound loss of contrast sensitivity in patients with early PSC cataracts who maintain relatively good acuity (20/40 or better) on Snellen's test. Examination of 122 such eyes revealed wide variations in contrast sensitivity, with Arden scores showing better correlation with subjective complaints than with Snellen acuity levels. While Snellen's test measures only one end of the spatial modulation transfer function (MTF), the Arden test plates provide an overall picture of MTF and help us to better understand the effect of PSC cataracts on visual function.