This is an extremely red eye that occurs when a blood vessel on the surface of the eye ruptures. The white part of the eye (the sclera) is covered by a very thin layer of skin called the conjunctiva. You can see this skin when looking in a mirror, as red blood vessels course through it and look like “lines” on the eye. If one of these blood vessels bursts for some reason, such as after a cough or sneeze, blood will track underneath the conjunctiva and make the eye look extremely red. It only takes a few drops of blood to make the eye look bright red and this can look quite alarming in the mirror. A subconjunctival hemorrhage is almost always harmless, but warrants a check to make sure there is no bleeding inside the eye (a hyphema or vitreous hemorrhage) and to make sure the cornea isn’t drying out.