In the 1950s, chronic corneal hypoxia and its attendant complications were associated with scleral contact lenses (ScCLs) compared to corneal contact lenses (CCLs).¹ Changes in mechanical design to improve transfer of oxygenated tears between the corneal-tear film interface were partially successful, but accompanied by increased complexity of lens fitting and design.² These included fenestrations, slots, truncations, and channels. Apart from being time consuming and technically difficult to manufacture, these modifications were almost invariably associated with trapping of air bubbles behind the ScCL, resulting in reduced vision and localised corneal desiccation. Without a sealed tear film, the ScCL rested progressively more on the corneal apex and limbus—that is, settling back, which caused corneal erosions, scarring, and hypoxia.

The advent …