November 4, 2022

Cooling and tears: Activating a natural pathway for instant relief

Cooling and tears: Activating a natural pathway for instant relief
Brandon Hauer, PhD
Time Read
8
min

TL;DR: Next time you need rapid dry eye relief, try a minute or two of refreshing cold on your eyes and feel the tears start flowing! Special “TRPM8” channels in your eyes are activated by cold sensations, and directly stimulate the lacrimal gland to produce natural tears. 

 

Imagine it’s around 2pm, Wednesday afternoon (for some of you right now, maybe it is!). You’ve been at your desk all day, sending emails, writing reports, or in several consecutive hours of virtual meetings. The latter one especially can be tricky, because you more or less have to stay planted at your desk, eyes fixed on your monitor.

Before long, you start to feel that itchy, stinging feeling in your eyes. Like you want to rub them, but even that doesn’t produce much relief.

Or maybe you’re rubbing the back of your neck, feeling some tightness or strain there. That, of course, could be feeding into that headache you’ve been fighting all afternoon.

You squeeze your eyes closed to try to get some relief, and maybe get a soothing tear or two as a reward for your efforts.

What I am describing here is digital eye strain. Digital eye strain is exactly this suite of symptoms that many of us have experienced, and can even kick in after only 2 hours using digital devices.

If you’re someone obligated to use devices for much of the day, you have likely experienced some combination of these symptoms before. The answer for many people is a classic “quick fix”: hydrating eye drops.

What we’re craving is that moisture, that feeling of soothing relief. But especially in recent years, we’ve become more aware of a natural pathway that evolved to respond to this type of irritation.

 

Specialized Cold Sensors

Transient receptor potential melastatin 8 (for your and my sake, let’s just refer to these in their abbreviated form as TRPM8) channels exist on your eyes.

There are several important roles served by TRPM8. Firstly, the pathway I mentioned above relies on TRPM8 channels to detect eye surface “dryness.” Their other role is complementary: TRPM8 channels can directly stimulate the lacrimal gland to secrete tears.

In practical terms, imagine it’s a blustery October afternoon. You’re waiting for a friend outside, and are in the unfortunate circumstance of staring into the wind. Your eyes notice right away – that wind rapidly evaporates the moisture on the surface of your eye, and you’ll likely start to blink to compensate.

But if you were to persist through this and, for whatever reason continue to stare unblinking into the wind, your eyes would start to water. It might seem peculiar at first, but it’s a natural adaptation to that evaporative cooling, to protect your eyes by producing tears.

These are the two key roles of TRPM8 channels working together. The eye feels too cool, because tears have started evaporating away, meaning your eyes must be dry. TRPM8 channels activate automatically in response to this, and directly stimulate tear production from the lacrimal gland.

So what am I saying here, that if your eyes feel dry, you should turn the oscillating fan up to max and have a good, hard look at it? Of course not. Instead, you could “shortcut” the system by activating those TRPM8 channels directly: With cold.


A Rapid Shortcut For More Tears

You see, TRPM8 channels respond to cooling sensations, whether from actual environmental thermal changes, or from certain chemicals.

Menthol, for example, with that cool, refreshing sensation you can imagine so easily, activates TRPM8 receptors. While that could, at least in principle, produce more tears, certain contraindications of menthol vapours (eye irritation, discomfort, and potentially damaging effects in patients with dry eyes) limit its usefulness.

Instead, researchers have been turning their attention to novel TRPM8 activators. Namely, a compound called C3 (cryosim-3) can activate TRPM8 channels in patients with dry or strained eyes. This can produce a lasting cooling effect, increasing tear secretion, and without any complaints of irritation or pain.

Other work has looked at regular, repeated application of C3 for the treatment of dry eyes. Topical application four times per day for one month improved Ocular Pain Assessment Survey (OPAS) scores, quality of life, and Schirmer test results in patients with dry and strained eyes.

There is even some evidence of TRPM8 channel dysfunction in those with dry eyes.

Refreshing Cool for Rapid Relief

Of course, all of these studies rely on pharmacological agents to exert their effects. Given that cold can similarly activate TRPM8 channels, we started looking into a chilly refresh as a way to avoid the specialized compounds.

This is the inspiration behind REST’s built-in Rise setting, offering 90 seconds of therapeutic cold. We’ve had countless reports from users who have expressed their surprise and delight at just how quickly and robustly the cold produces tears for them.

Our hope is that we’ll have people reaching for a quick cold session from REST before they reach for their artificial eye drops, whether first thing in the morning, mid-day at work, or whenever they might feel the need for quick relief.

This cooling has the added benefit of reducing inflammation, and especially first thing in the morning, can help users to wake up feeling refreshed and alert.

So the next time you feel any of those digital eye strain symptoms, that need for a break or quick relief, try a minute or two of cooling on your eyes. You might be surprised at how quick the tears start flowing, and you’ll have your TRPM8 channels to thank for kickstarting it.