Humans cannot survive without oxygen, and the eyes cannot breathe without oxygen. However, because the cornea does not have blood vessels, it cannot obtain sufficient oxygen from the blood, and wearing contact lenses will hinder the eyes from obtaining oxygen from the atmosphere, so the wearer often causes discomfort due to corneal hypoxia. How can this be avoided?
Under normal circumstances, tears cover the cornea to form a thin tear film. Oxygen in the atmosphere will first dissolve in the tear film and then be absorbed by the cornea. When wearing contact lenses, the lens is attached to the outside of the tear film, which will affect the exchange of oxygen, and may also destroy the protective effect of the tear film. In the case of prolonged hypoxia, corneal cells may be damaged, and if you wear contact lenses to sleep, it will cause the cornea to "suffocate", and in severe cases, it will lead to lesions or blindness.
Compared with transparent films, the currently popular colored contact lenses are actually even worse in terms of oxygen permeability, because colored contact lenses often adopt a "sandwich" process in which the colored layer is sandwiched between two lenses. This not only increases the thickness of the lens, but also further affects the oxygen throughput.
So, what can we do to prevent corneal hypoxia? Although high water content means that the lens contains more water, if the lens is worn for a long time or the environment is dry, the lens will absorb tears to replenish water, so if the eyes are already dry, you can choose a contact lens with a lower water content. If you are in an indoor environment for a long time, your eyes will lose water quickly, and you will be prone to dryness and fatigue when wearing contact lenses. Care should be taken to use your eyes properly and drop a few drops of artificial tears or eye moisturizers when necessary to relieve them.