SOUTH SAN FRANCISCO, Calif.—A joint project to develop a glucose-sensing contact lens is being put on hold by Verily, the life sciences unit of Google parent Alphabet, and Novartis’ Alcon division. “We are at a point where we have decided, together with Alcon, to put the glucose-sensing lens work on hold, while continuing to focus on the smart accommodating contact lens and smart intraocular lens projects,” Verily CEO Brian Otis wrote in a November 16 post on Verily’s blog. Otis said the project, which began in 2014, has run into difficulties associated with “the challenges of obtaining reliable tear glucose readings in the complex on-eye environment.”

An Alcon spokesperson added, “Substantive clinical work on the glucose-sensing lens demonstrated that there was insufficient consistency in our measurements of the correlation between tear glucose and blood glucose concentrations to support the requirements of a medical device.”

The glucose-sensing contact lens project is part of a broad Smart Lens initiative by Verily and Alcon that includes the development of an accommodating contact lens for presbyopia and a smart intraocular lens for sight improvement post-cataract surgery. A timetable for the commercial release of either lens has not been announced.