A subconjunctival hemorrhage is a bleed beneath the surface of the eye (known as the conjunctiva). The most common cause is a burst blood vessel underlying the conjunctiva. 

The blood vessels which supply the eye are small and fragile. They can be easily damaged by actions such as:

• Sneezing
• Coughing
• Vomiting
• Heavy lifting / straining
• Repeated eye rubbing or other eye trauma
• Extreme g-force

These actions can cause a blood vessel to burst resulting in a subconjunctival hemorrhage. 

First aid for a subconjunctival hemorrhage

Although a subconjunctival hemorrhage can appear dramatic, it is often a harmless and painless condition which resolves with no need for medical intervention.

In some cases a subconjunctival hemorrhage can be a sign of a more serious underlying medical condition such as high blood pressure or problems with the blood clotting (coagulopathy). 

There is no acute first aid treatment for this condition. If concerned you should seek medical attention or visit an optician.