Conjunctiva

The conjunctiva is a thin membrane interlaced with blood vessels that connects the eyeball to the eyebrows. It enables the eyelids to glide over the anterior portion of the eye and, like the tear film, it protects the eye. In the event of excessive irritation/stress from the outside, the blood supply in the blood vessels can increase, boosting the capillary exchange of substances to counter the irritation. When this happens, the eyes redden.