From oxygen to the ocular surface: where next for GP lens materials?

   For over half a century, rigid gas permeable (GP) contact lens material development has focused on increasing oxygen permeability (Dk). Modern hyper-Dk materials such as Optimum Infinite and Breathe have largely overcome corneal hypoxia, but further gains in Dk offer diminishing clinical returns and make it increasingly difficult to maintain the overall balance of material properties. Today, the main barriers to successful GP lens wear are comfort-related, determined not only by wettability but also by surface lubricity and the interaction of the lens with the tear film, eyelids and ocular surface. Future progress is shifting from modifying the bulk material towards developing durable or renewable surface technologies that become an integral part of the lens and ensure harmonious interaction with the eye.