The Sleep Tight Video©
Help for sleepless parents
This is literally a "broken blood vessel" on the surface of the eye. It appears as a bright red blood-colored patch of varying size on the surface of the globe of the eye (but not invading the area of the pupil1. It is painless, and the patient is unaware of the condition unless he or she looks in a mirror.
Newborns may exhibit this condition as a result of vaginal delivery (and mothers may have it from pushing extra hard). Later in childhood, it can result a hard sneeze or coughing spell, or even from a blow or scratch to the eye. In this latter case, one would be concerned about a corneal abrasion or hyphema. And sometimes there is no discernible cause at all - it is just there one day.
The prognosis for simple subconjunctival hemorrhage is excellent - they all disappear without any treatment whatsoever in 2-3 weeks.
1. Which would be a hyphema - blood in the pupillary cavity (anterior chamber) of the eye. Hyphemas are serious and need immediate medical attention by an ophthalmologist.