Whats the cause of one bloodshot eye?
Bright redness of the whites of the eyes can occur when the tiny blood vessels covering the whites of the eyes rupture from trauma or changes in pressure within the head (for example, after forceful laughing or vomiting, when diving under water, or even bending upside down). This condition is called subconjunctival hemorrhage, it is generally harmless. It causes a local area of the white portion of the eye (the sclera) to become brilliantly reddened.
