Prentice Medal lecture: contact lens wettability--myths, mysteries, and realities.

The author shows that the wetting of contact lens on the eye is a complex process. Measuring the contact angle is possible by several techniques but knowing the contact angles (advancing and receding) is not enough to define wettability in scientific terms. A contact lens on the eye, bathed in lacrimal fluids and subjected to a number of pressures, presents a challenging problem in physics as well as in clinical vision care.