Mild conjunctival congestion manifests only as superficial vascular filling of the conjunctiva, evident in the fornix and decreasing towards the corneal limbus.
Severe congestion manifests as bright red. Rupture of the conjunctival vessels for various reasons manifests as a subconjunctival accumulation of blood, usually dark red, which gradually changes to a yellowish colour containing ferritin with time and gradually returns to the normal conjunctival colour.