Smart Contact Lenses Treat Depression-Like Behaviour in Mice

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

Credit: UNSPLASH

This work is still at an early stage, with findings so far limited to a single mouse study. The eye is a useful access point for medical technology, with light passing through the cornea and lens before reaching the retina.

The retina converts light into electrical signals carried to the brain through the optic nerve. Smart contact lenses have previously been designed to monitor eye conditions like glaucoma, track pupil size, and monitor glucose levels.

The latest research attempts something different: using the eye as a route into the brain itself. The contact lenses contain tiny electrodes that send mild electrical signals through the retina.

Researchers used a technique known as temporal interference, where two slightly different electrical frequencies are delivered simultaneously. The signals are designed to become fully active only where they overlap, allowing researchers to target specific brain regions linked to mood regulation.

This process is compared to two weak torch beams crossing to create a brighter point where they meet. In theory, the approach could stimulate brain circuits known to be linked to depression.

The experiments were carried out in mice injected with a stress hormone to create depression-like behaviour. Researchers acknowledge this does not fully reflect human depression.

For the study, miniature contact lenses were fitted to mice with damaged photoreceptors, meaning their vision was already impaired. This was necessary because normal visual activity would interfere with the electrical signals passing through the eye.

The technique, as tested, would therefore not work in animals or people with healthy retinas. Human eyes constantly adjust focus by changing the shape of the lens, something mouse eyes do not do in the same way.

That movement could disrupt signals delivered through a contact lens placed on the cornea. The technology also faces practical challenges, including careful fitting to avoid damaging the cornea and needing to be kept clean to reduce infection risk.

Any medical data collected by smart lenses would also require strong safeguards. Making the lenses is very expensive, and researchers note the technology is not yet commercially viable on a large scale.

A recent review highlighted the manufacturing difficulties involved in creating smart contact lenses. Depression itself is also difficult to model in laboratory animals.

Symptoms, causes, and severity vary widely between patients, making it hard to draw direct comparisons from experiments involving stressed mice raised in controlled laboratory conditions. Non-invasive brain stimulation is an established area of medical research, and this work may help with future studies.

However, results from a small mouse experiment involving animals with impaired vision are still a long way from a treatment that could be used in humans. Nonetheless, the idea of treating depression using smart contact lenses is intriguing, and this early work adds a creative new thread to the broader search for novel treatments for depression.

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Scientists in South Korea developed experimental smart contact lenses.

The lenses appeared to improve depression-like behaviour in mice.

The technology sends electrical signals through the retina to mood-linked brain regions.

Source: The Conversation