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Have you ever wondered why our eyes not only never freeze, but don't even feel cold? They are not covered with wool that could warm them. And the vitreous body, which for the most part consists of the organ of vision, contains Susan Standring; Neil R. Borley; et al., eds. (2008). Gray’s anatomy: the anatomical basis of clinical practice (40th ed.) 98% water. So what's the point then?
Well, Mother Nature should be thanked for that. Our eyes are designed so that they can be used in any weather.
Somehow, the American military wanted to know if it was safe to wear lenses during combat operations in cold regions. And in 1982, the biomedical company LinCor Biosciences conducted an experiment on their order J. F. Socks. Contact lenses in extreme cold environments: response of rabbit corneas / Am J Optom Physiol Opt to understand whether these products can "freeze" to the eye.
Experiments were conducted on rabbits. They were put on contact lenses and exposed to wind for 3 hours, the speed of which reached 125 km/h. At the same time, the air temperature was -28.9 °C, and the wind-cold index (that is, the subjective feeling when exposed to frost and wind at the same time) was J. F. Socks. Contact lenses in extreme cold environments: response of rabbit corneas / Am J Optom Physiol Opt as much as -67.8 °C! But none of the poor rabbits lost their eyesight, and none of the lenses froze to their eyes. The subjects had only a slight redness, which disappeared after a couple of hours.
David Thomas, a marine biologist from the University of Wales and a polar explorer, writes in his book "Survival in Antarctica" D. N. Thomas, R. Mears. Surviving Antarctica that the resistance of eyes to frost is explained by their location. That is, by the fact that they are suddenly in your head. And it maintains a temperature of about 36.5–37 ° C, as in the whole body. Therefore, the eyes are never cooled enough to freeze.
The eyeballs of a dead body will really freeze. But as long as you are alive and radiating heat, this will not happen.
Add in the fact that the eyes are constantly being washed D. N. Thomas, R. Mears. Surviving Antarctica tears, and their production in the cold increases. They consist mainly of water, but they also contain a lot of salt, which lowers the freezing point. This allows our visual organs to stay hydrated even in the cold.
In addition, the cornea, the most prominent transparent part of the eye that refracts light, is small J. K. Slettedal, A. Ringvold. Why doesn’t the cornea freeze? / ARVO Journals is prone to frostbite. The fact is that there are no blood vessels in it. And the space between it and the iris, which is called the anterior chamber, is filled with watery moisture (Latin humor aquosus). And it also nourishes the cornea.
In 2014, scientists from the University Hospital of Oslo conducted a study J. K. Slettedal, A. Ringvold. Why doesn’t the cornea freeze? / ARVO Journals by freezing donor corneas with liquid nitrogen to -40 °C. And they found out that watery moisture, consisting of water, electrolytes and amino acids, due to its composition provides a constant eye temperature of about 37 °C.
Does this mean that they are completely immune to the cold? No, low temperatures can cause How to Protect Your Eyes in the Winter / Boulder Medical Center dryness and rapid evaporation of tear fluid. And if you put up with it for a long time, you can earn serious vision problems.
In addition, the already mentioned cornea may freeze for a short time under the influence of strong wind and cold T. A. Cope, A. Kropelnicki. Case Report: Eye injuries in the extreme environment ultra-marathon runner / BMJ Case Rep , which is fraught with its abrasion. This condition is accompanied by severe discomfort, redness of the eyes, lacrimation and sensitivity to light. Marathon runners and rock climbers who neglect safety glasses suffer from corneal abrasion.
But if you use drops to moisturize and avoid dehydration, as well as close your eyes from the wind, you have nothing to fear even on the coldest days.
