"The skin breathes” Ever heard that phrase? Well, it's not just a figure of speech. Under normal conditions, atmospheric oxygen can supply the upper layers of the skin to a depth of 0.25-0.40 mm! For this reason, there are almost no vessels in the epidermis (although oxygen can "reach" the upper layers of the dermis). An identical mechanism of oxygen delivery exists in the cornea (it also has no vessels and is directly fed). This mechanism is possible due to the diffusive properties of oxygen.