One can envision the eyeball as a hallow onion with three layers: the innermost being the retina and its supporting structures (the light sensitive layer which enables vision), the next layer out the sclera (the "white" part of the eye) and the outermost layer the conjunctiva, the "skin" of the eye which covers the white part going back and folds on itself to cover the inner part of the eyelid.

There are thousands of small invisible blood vessels that course between the conjunctiva and sclera and should one of them break, which can happen with trauma, eye movement, straining, coughing, then blood collects in the space between the sclera and conjunctiva and is technically referred to as a "subconjuctival hemorrhage" - blood underneath the conjunctiva. In general, there is little sensation associated with this and most people are unaware of the hemorrhage until someone points it out or they look in the mirror. In about half the cases, there is an association with increased blood pressure. In rare cases there are known associates with disorders of blood vessel fragility and possible extension of blood vessel disorders within the eye-socket (orbit). With the use of blood thinners, the subconjuctival hemorrhage can get quite large and needs closer monitoring.

If there is any pain, decreased vision or a recurrence of the hemorrhage, then a visit with an ophthalmologist would be helpful to rule-out any vision threatening problems.

Aarchan Joshi, M.D.
Diplomate, American Board of Ophthalmology
Member, South Bay Independent Physicians Medical Group, Inc.