Subconjunctival haemorrhage
Subconjunctival haemorrhage is a superficial bleed beneath the conjunctiva causing a sharply demarcated bright-red patch with normal vision; it is usually harmless, but pain, visual change or trauma means the diagnosis must be reconsidered urgently.
Definition
A subconjunctival haemorrhage is bleeding from a small conjunctival or episcleral vessel into the space between the conjunctiva and sclera. It produces a flat, sharply demarcated red patch and, when isolated, does not affect vision or intraocular structures.
First principles
A superficial vessel has bled outside the eye
A small conjunctival or episcleral vessel ruptures into the loose space over the sclera. The transparent conjunctiva makes the blood look vivid, but the cornea, anterior chamber, retina and optic nerve are not involved, so an isolated bleed should not reduce vision or alter the pupil.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.