Sixty-five-year-olds should drive cars with windshields because with age the eye's lens becomes transparent.

The answer is untinted; more cloudy.  The normal 50-year-old driver needs twice as much light to see too after dark as a 30-year-old. In dim or dark light, eyes adjust by broadening the pupils to let in light as could reasonably be expected. The iris contains small muscles that control the span of the pupil. As you get older, these muscles debilitate and don't react too to the need to let in more light. The outcome is a small pupil when you try to find in poor light.