Smart contact lenses (CLs) have long captured the imagination, featuring in headlines as futuristic devices capable of diagnosing disease, delivering drugs and even displaying digital information. The field is advancing rapidly, but how close to fruition is the full potential of smart CLs?

“There’s an enormous amount of research going on that will keep us busy in the clinic tomorrow,” says Dr Debarun Dutta MCOptom, Senior Lecturer and Lead for Contact Lens Education at Aston University. Yet he is quick to emphasise that most technologies remain investigational, with only a handful approaching meaningful clinical translation (Kazanskiy et al, 2023).

Interest in smart CLs is growing fast in what is a fascinating combination of biomedical engineering and clinical application, as well as regulatory and commercial viability (Seo et al, 2023). Despite this momentum, no fully integrated smart lens is currently available for mainstream clinical practice. Instead, the near-term picture is one of niche applications, cautious progress and realistic expectations.

At the heart of smart lens development is the tear film, which is an often-overlooked but information-rich biological fluid.

“The tear film is easily accessible, continuously replenished, and reflects both ocular and systemic physiology,” says Professor Ali K Yetisen, Director of the Centre for Biochemical Sensors at Imperial College London. “It contains biomarkers such as electrolytes, inflammatory cytokines, proteins and metabolites, which can change early in conditions such as dry eye, glaucoma, neurodegenerative and infectious eye diseases.”

This makes tears an attractive target for minimally invasive monitoring. Unlike blood sampling, tear analysis could be continuous and unobtrusive, at least in theory. The challenge lies in translating this promise into devices that are safe, comfortable and clinically meaningful.