Fig. 13. Double slab-off lens with thin zones inferiorly and superiorly that cause the lens to rotate to the proper position and then remain in place. (Stein HA, Freeman MI, Stein RM, Maund LD (eds): Basics of Soft Contact Lenses. In: Contact lenses: Fundamentals and Clinical Use, p 88. Thorofare, NJ, Slack, 1996)