The clinical progression of the cataract may be influenced by drugs which reduce the denaturation of lens proteins. One of the most promising drugs is the bendazac-lysine salt. The drug was used in a double-blind study of a group of patients with initial cortical cataract in order to evaluate the changes in visual acuity and contrast sensitivity by means of a psychophysical and an electrophysiological method. After 6 months of treatment with bendazac the mean values of visual acuity showed a statistically significant increase in respect to baseline values, as well as an improvement of the threshold of contrast for most spatial frequencies. In the eyes treated with placebo there was no statistical difference between the visual acuity at baseline and after the treatment, but an increase of the contrast threshold for many spatial frequencies. The treatment with bendazac, when compared to the administration of placebo, leads to a statistically significant improvement of the contrast threshold and induces a global improvement on the visual conditions.