Hikers have enough to worry about without making a big issue about their eyes. They worry about hydration, nutrition, fatigue, heat, cold and getting lost. Yes, many hikers wear sunglasses to reduce glare and keep their eyes from getting quite so tired. And yes, they wear sweat bands to keep the perspiration out of their eyes. And yes, both these precautions are well advised. But still, vision is usually not their highest priority.
No matter what precautions a hiker takes or doesn’t take, it’s important to understand exactly what is happening to their eyes when they go on a long, exhausting hike, or when they are exposed to glare, or when they get perspiration in their eyes. Is getting perspiration in the eyes dangerous or is it completely harmless? Can it cause permanent damage? What can be done to keep eyes comfortable and working properly when hiking?
Here are some answers: When you get dehydrated from perspiration and strenuous activity, it tends to affect your eyes long before other body systems. As a result, your eyes produce less tears and the all-important protective tear film, which is critical to vision, becomes under-moisturized. As a result of too little water, the salt concentration in the tear film increases, causing burning, discomfort, fatigue, etc. The really bad news is that too little moisture and too much salt in the tear film can very quickly begin to cause ulceration of the protective membrane over the cornea. If nothing is done about it, this can be lead to permanent eye damage and even blindness.
The good news is that beginning corneal ulcerations usually heal very quickly once the tear film’s water/salt balance is restored. Still, it’s wise not to take changes or let it go too long.
Solar glare and UV radiation can also cause tear film moisture loss, thereby increasing the salt concentration.
Now you might ask, if the tear film is made up of salt, water and oil, and perspiration is also made up of salt, water and oil, why is to so uncomfortable to get sweat in your eyes? The reason is that perspiration contains far more salt than do tears. Just a little perspiration in the eyes can cause the tears to start eating into the cornea’s protective membrane.
In short, not only is getting sweat in the eyes uncomfortable, it absolutely can cause damage.
Suggestions: Wear your sunglasses, wear your headband and carry a pure-water eye mist moisturizer that, when applied to the eyes, will instantly restore the tear film’s water-to-salt ratio.