The eyes are not afraid of cold on cold days mainly because of the special structure of the eyes. The human body surface is distributed with many receptors that can feel the change of heat and cold, in a cold environment, the body surface temperature will also fall, thus stimulating the body surface of the heat and cold receptors, and then through the nervous system to transmit the “cold” signal to the brain, so that people feel the “cold The presence of “cold”. The eyes are not afraid of cold mainly because of the lack of heat and cold receptors, the weakness of heat dissipation, the blinking and turning of the eyes and the eyelid skin that protects the eyeball. First, the eye is composed of a variety of tissues, including the eyeball, orbit, appendages (eyelids, conjunctiva, lacrimal apparatus) and blood vessels, nerves, etc. Although the eye is rich in tactile and nociceptive nerves, there are no nerves for sensing heat and cold, i.e., cold and heat receptors, and very few cold and heat receptors on the conjunctiva and eyelid skin, so the eye is extremely slow to sense changes in heat and cold. In cold weather, there are no cold and heat receptors to send signals to the brain, and the eyes are not afraid of cold. Secondly, there are no blood vessels in the cornea and iris that make up the eye, so heat dissipation is weak, and the rate of feeling cold is slowed down, so if the heat emitted is less than the heat absorbed, the cold will not be felt. In addition to this, the constant blinking of the eyes and the constant turning of the eyeballs generate abundant heat. In addition, the eyeball is protected by the skin of the eyelid in front of the eye, which keeps the eye at a certain temperature while reducing heat dissipation, so even though the eye is always exposed, it is not afraid of being cold on cold days. However, although the eyes will not feel the cold on a cold day, they may tear in the wind if they are in a cold wind, which can easily lead to dry eyes and other eye diseases, so you still need to pay attention to protection.