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Originally Posted On: https://bluefinvision.com/blog/why-a-sudden-blood-red-eye-looks-frightening-but-is-usually-harmless/
A bright red patch spreading across the white of your eye can be alarming. It looks dramatic, even painful. Yet in most cases, this striking appearance is caused by something entirely benign: a subconjunctival haemorrhage.
I was recently asked to comment on a case widely covered in the media, where a prominent public figure appeared with a visibly bloodshot eye. You can read the full article in the Daily Mail. The coverage prompted many people to ask the same question: should a blood-red eye be a cause for concern?
Here is what you need to know.
What Is a Subconjunctival Haemorrhage?
A subconjunctival haemorrhage occurs when a tiny blood vessel breaks just beneath the conjunctiva, the clear membrane covering the white of the eye. Blood pools in this space, creating a vivid red or dark patch that can look far worse than it feels.
Most people notice no symptoms at all beyond the appearance. There is usually no pain, no discharge, and no change to vision.
What Causes It?
The most common causes include:
- Sneezing, coughing, or straining (such as lifting something heavy)
- Rubbing the eye
- Minor trauma or a knock to the face
- High blood pressure
- Blood-thinning medications such as aspirin or warfarin
In many cases, there is no obvious trigger at all. The vessel simply breaks spontaneously, often during sleep.
When Should You Be Concerned?
A subconjunctival haemorrhage on its own is rarely serious. However, there are situations where further assessment is sensible:
- Recurrent episodes: If this happens repeatedly, blood pressure and clotting function should be checked
- Associated symptoms: Pain, vision changes, or discharge suggest a different condition
- Recent significant trauma: A blow to the head or eye area may warrant examination to rule out deeper injury
- Use of anticoagulants: Patients on blood thinners should mention this to their GP or eye specialist
If none of these apply, the haemorrhage will typically resolve on its own within seven to fourteen days. The red patch gradually fades to yellow or brown before clearing completely, much like a bruise elsewhere on the body.
What It Is Not
A subconjunctival haemorrhage is not the same as conjunctivitis. There is no infection, no itching, and no sticky discharge. It is also unrelated to problems inside the eye, such as retinal bleeding or glaucoma. The bleeding sits on the surface only.
A Consultant-Led Approach to Eye Health
At Blue Fin Vision®, we understand that any sudden change to your eye’s appearance can feel worrying. Our consultant-led assessments use advanced diagnostic imaging, including OCT scanning, to ensure nothing is missed and to provide clear, evidence-based reassurance.
If you have experienced a subconjunctival haemorrhage and are unsure whether further investigation is needed, book a consultation with our team. We are here to explain what is happening – and, just as importantly, what is not.
