Scientists in South Korea have developed experimental contact lenses designed to send electrical signals through the retina and into brain regions linked to mood. In mice, the technology appeared to improve depression-like behaviour.

The idea sounds futuristic: a contact lens that could one day help treat depression by stimulating the brain through the eye. The work is still at a very early stage, with findings so far limited to a single mouse study.

The eye is already one of the body’s most useful access points for medical technology. Light passes through the cornea and lens before reaching the retina, which converts it into electrical signals carried to the brain through the optic nerve. Because of this close connection, researchers have spent years developing technologies that use the eye to monitor disease.

Smart contact lenses have already been designed to monitor some eye conditions, such as glaucoma. Other smart contact lenses can track pupil size as an indicator of nervous system activity, since the iris........

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