The Use of Guide Tubes and Plastic Covers in Testing Ophthalmic Lenses for Impact Resistance

This paper studies the effect of drop ball testing through a protective plastic envelope or film, and of the use of a tube to guide the ball in its fall to the lens. In addition, comments are made on the special dispensation given by the Food and Drug Administration to the design testing of raised ledge multifocals and other lenses, rather than drop ball testing each lens individually.