Emerald™ lenses feature a unique reverse geometry lens design. A customized 4 zone lens design employs base curves calculated to be flatter than the flat cornea curvature, reverse zones of steeper radii, and alignment zones that provide improved lens positioning. As result, positive-negative pressures between the Emerald lens and cornea achieve the desired myopic reduction quickly and systematically, while worn during sleep. Emerald lenses are made of Boston® Equalens® II, a stable, high DK extended wear material from Boston, the leader of gas permeable materials and solutions.