What Has Dopamine Got to Do with Myopia?

Most of us have heard of dopamine—it’s that chemical tied to pleasure, reward and motivation. But here’s an interesting twist: dopamine might also play a role in short-sightedness, or myopia.

If you haven’t yet read up on what myopia is, here’s a short aside: Myopia is an increasingly common eye condition that is affecting a high proportion of children globally. Primarily, lifestyle factors are to blame for this epidemic of myopia. The issue is the eyeball grows too much, due to the way our eyes work when we do too much close work, or spend too much time indoors.

One of the most established theories behind the development and progression of myopia is lack of outdoor time and too much time doing near work . One suggestion for this occurring is reduced dopamine levels. Apparently, dopamine can help prevent eyeball elongation (increase in axial length). Outdoor time helps to increase our dopamine levels, and outdoor time has been shown to be protective against the onset of myopia and may help slow the progression of the condition.

The theories of myopisation. ©Jason Higginbotham

A contact lens manufacturer, Safilens, has come up with a rather novel idea. They’ve developed a daily disposable soft lens called Delivery Tyro. Not only does it correct a child’s vision, like any standard lens, but it also contains tyrosine embedded in the lens material. Over the course of the day, this substance is released into the eye and appears to mimic the action of dopamine, helping to regulate the development of the eye’s structure.

 30-day supply box of Delivery Tyro daily disposable contact lenses

Early evidence has shown considerable effectiveness in slowing the rate of eyeball growth. According to Safilens’ internal studies, the Delivery Tyro helped reduce eyeball growth by up to 85% from expected levels. This study used 159 subjects between 9 and 23 years old. It goes to show also that myopia management continues well beyond the teenage years.

According to Safilens’ internal studies, the Delivery Tyro helped reduce eyeball growth by up to 85% from expected levels. The study involved 159 participants aged 9 to 23 years—which also highlights an important point: myopia management doesn’t necessarily stop in the teenage years.

 Table showing the effects of the Tyro lens (orange) against expected rates of eyeball growth (grey).

A larger scale study known as an independent peer-reviewed clinical trial is underway with much larger numbers of subjects in the study.

The contact lens acts as a sponge, holding the tyrosine in the body of the lens. During the day, whilst being worn, the tyrosine leaves the lens and is absorbed by the cornea (the front surface of the eye that the contact lens rests on).

The eye absorbs the tyrosine, and it is acted upon by natural chemicals in the eye and has the effect of increased levels of dopamine, the natural substance that is released when we spend time outdoors in sunlight that has been shown to slow growth of the eyeball.

Body temperature, blinking and natural pressure from the eyelids causes the Tyrosine to be released constantly over the course of the day.

Lots of studies have been shown that children are excellent at complying with the correct techniques and protocols for safely wearing contact lenses.

They will also be more able to take part in many outdoor sports and activities that may be less convenient with spectacles.

It will be interesting to see the results of the larger clinical trial to see just how effective these lenses and Tyrosine are.

It could be, with those levels of efficacy, that many children will avoid high myopia in later life, a major cause of sight threatening conditions as sufferers get older.