Seeing a sudden bright-red patch on the white of your eye can be alarming. In most cases it’s a subconjunctival haemorrhage — a tiny blood vessel has burst beneath the clear surface layer (the conjunctiva), letting blood pool on the white part (sclera). Because the blood sits on the surface and not over the cornea, vision is usually normal. It’s typically painless, with no discharge, and it clears on its own as the eye re‑absorbs the blood — much like a bruise — over one to three weeks.
This article outlines the key triggers, medical risk factors and how serious it usually is; the red flags that need urgent care; what to expect at diagnosis; simple self‑care that actually helps; how long recovery takes; and prevention tips. If a red eye has you worried, the next sections will guide you.
What symptoms you may (and may not) notice
The hallmark of a conjunctival haemorrhage is a sharply defined, bright‑red patch on the white of the eye. It’s usually painless, vision stays normal, and there’s no discharge. Many people discover it in the mirror or when someone points it out. The blood sits under the clear surface, so it won’t wipe away. You might notice mild grittiness or dryness, but most eyes feel completely normal.
- Common signs: Bright‑red patch on one eye; normal vision; eye otherwise feels fine; mild irritation or dryness possible.
- Usually absent: Pain, discharge, swelling or blurred vision. If these occur, they warrant medical advice.
Key triggers that cause a conjunctival haemorrhage
Most conjunctival haemorrhages are set off by a brief rise in pressure in the head and neck (a Valsalva manoeuvre) that makes delicate surface vessels pop. Everyday actions can do this, and minor knocks to the eye can too. Sometimes the cause of conjunctival hemorrhage isn’t obvious and it happens spontaneously.
- Strong coughing or sneezing: Sudden pressure spikes can rupture tiny vessels.
- Straining: Including constipation on the toilet or heavy lifting/bending.
- Vomiting: Forceful retching has the same pressure effect.
- Rubbing the eye hard: Friction can break a surface capillary.
- Minor trauma: A fingertip, makeup wand, or a stray ball can bump or poke the eye.
- Contact lens use: Dryness and friction from lenses or handling can trigger bleeding.
Underlying conditions and risk factors to know
Some people are more prone to subconjunctival haemorrhage because of health or eye factors. If you’re getting repeated bleeds, it’s worth checking for the cause of conjunctival hemorrhage rather than assuming it’s bad luck. The following well‑recognised conditions and risks make fragile surface vessels more likely to leak, so your doctor may review blood pressure, medicines and medical history.
- Ageing (especially 65+): More fragile conjunctival blood vessels.
- High blood pressure: Pressure spikes and vessel stress raise risk.
- Diabetes: Microvascular changes make surface bleeding more likely.
- Blood thinners/aspirin: Warfarin or aspirin can tip minor bleeds.
- Clotting disorders: Conditions like haemophilia or von Willebrand disease.
- Contact lenses/eye surgery/inflammation: Friction or recent procedures irritate the conjunctiva.
Is a subconjunctival haemorrhage serious?
Usually, no. A subconjunctival haemorrhage looks dramatic but is typically harmless, doesn’t affect vision and clears on its own within one to two weeks (larger patches can take a little longer). It becomes more important if it follows significant eye trauma, keeps recurring, or you’re on blood thinners or have high blood pressure or diabetes — in those cases your doctor may check for an underlying cause. Seek care promptly if there’s pain, light sensitivity, discharge or any vision change.
When to seek medical care
Most subconjunctival haemorrhages don’t need treatment, but there are clear times to get help. If the red patch follows a significant eye injury, or if any pain, discharge or vision change develops, don’t wait. Likewise, if episodes keep returning or you’re on blood thinners, it’s sensible to have your blood pressure, medicines and general health reviewed. Most spots fade within one to two weeks (larger ones can take up to three).
Seek same‑day care if: There was eye trauma; you have eye pain, light sensitivity or headache; vision is blurred or shadowed; there’s discharge; or you notice a dark pool of blood in front of the coloured part (possible hyphema).
Book a prompt appointment if: Haemorrhages recur; you’re on warfarin/aspirin or have easy bruising; you have high blood pressure or diabetes; or the redness isn’t improving after two weeks or hasn’t cleared by three.
How doctors diagnose a red eye like this
Doctors usually diagnose a subconjunctival haemorrhage at a glance. They’ll ask about coughs, sneezes, straining, rubbing or trauma, contact lenses and blood‑thinning medicines to identify the likely cause of conjunctival hemorrhage. A brief torch or slit‑lamp exam confirms blood under the conjunctiva, with a clear cornea and normal vision. Blood pressure is often checked; recurrent cases may need clotting tests.
- History: Pressure‑raising triggers, contact lenses, surgery, and anticoagulant use.
- Examination: Vision and pupils, cornea and anterior chamber; rule out hyphema.
Treatment, self-care and what helps symptoms
Good news: most subconjunctival haemorrhages don’t need treatment and clear on their own. There’s no drop that speeds the blood’s re‑absorption, but you can ease any mild irritation. Use lubricating artificial tears as needed and avoid rubbing or pressing on the eye. If you’re on blood thinners, don’t stop them unless your doctor advises. If episodes recur, address the likely triggers and have your blood pressure and medicines reviewed.
- Artificial tears: Preservative‑free lubricating drops can soothe dryness or grittiness.
- Hands off: Avoid rubbing or touching the eye while it heals.
- Pause contact lenses: Switch to glasses until the eye feels comfortable again.
- Ease pressure spikes: Try not to strain; manage coughs/sneezes gently where possible.
- Treat the cause, not the spot: Recurrent bleeds merit a check of blood pressure, diabetes status and anticoagulant levels with your GP or eye specialist.
How long it lasts and what healing looks like
A subconjunctival haemorrhage is a surface bruise of the eye. Most clear without treatment in about one to two weeks; larger patches can take up to three. Vision should stay normal throughout. As the trapped blood breaks down, the colour shifts — you’ll see it fade rather than vanish overnight — and mild grittiness may settle with lubricating drops.
- Days 1–3: Bright, sharply outlined red patch that won’t wipe away.
- Days 4–7: Colour deepens to maroon/brown; edges soften.
- Week 2+: Yellow tint as it resolves.
- See a doctor: If no improvement by two weeks or not cleared by three.
Prevention tips to reduce future episodes
Not every subconjunctival haemorrhage can be prevented, but small habits can limit common triggers behind the cause of conjunctival hemorrhage. Focus on reducing pressure spikes, protecting the eye and keeping the surface comfortable. If you have risks, review them with your GP.
- Don’t rub; lubricate: Use preservative‑free artificial tears.
- Avoid straining: Treat coughs/constipation; go easy lifting/bending.
- Contact lens care: Keep lenses clean, well‑fitted; take breaks.
- Protect the eye: Wear safety eyewear for sport or DIY.
- Manage risks: Check blood pressure; discuss blood thinners; recurrent bleeds—screen for diabetes/clotting disorders.
Special situations and what to do
Some situations call for more than simple watch‑and‑wait. They don’t usually change the good outlook, but they can point to the cause of conjunctival haemorrhage or raise the bar for caution. If any of the following apply, take the specific next step.
- Newborns: Common post‑birth; mention to your midwife/GP.
- Children/trauma: Any blow or unexplained bruise—get checked.
- Contact lenses: Pause wear; review fit/hygiene first.
- Blood thinners or recent surgery: Don’t stop; call GP/surgeon.
How this differs from conjunctivitis and other red eyes
Not every red eye is “pink eye”. A subconjunctival haemorrhage is a sharply bordered, bright‑red patch on the white of the eye, with normal vision and no discharge or pain. Conjunctivitis generally makes the whole eye look pink or red and brings irritation and discharge. Other causes of red eye tend to add pain, light sensitivity, or blurred vision — features you don’t see with a simple surface bleed from the cause of conjunctival hemorrhage.
- Subconjunctival haemorrhage: Sharp, bright‑red patch; painless; no discharge; vision normal.
- Conjunctivitis (viral/bacterial/allergic): Diffuse redness; itching/grit; watery or sticky discharge, crusting on waking; may be contagious.
- Corneal scratch/infection: Marked pain, tearing and light sensitivity; possible blur — needs prompt assessment.
- Hyphema: Dark pool of blood in front of the iris with pain/vision change — urgent, same‑day care.
Frequently asked questions
Still worried about that sudden red patch? These quick answers cover the questions patients ask most about subconjunctival haemorrhage — daily life, how long it lasts, and when to be cautious.
- Is it contagious? No — it’s a surface bleed, not infection.
- How long, and do drops help? Usually 1–2 weeks (larger up to three). No treatment speeds healing; artificial tears can soothe.
- Will it affect vision? Vision should be normal; any blur, pain, discharge or light sensitivity needs prompt care.
- Is it linked to blood pressure or blood thinners? High BP and blood thinners raise risk; don’t stop them without medical advice.
Key takeaways
Most subconjunctival haemorrhages look dramatic but are usually harmless, painless and self‑resolving within one to three weeks. Common triggers include coughing, sneezing, straining, rubbing and minor knocks; risks rise with high blood pressure, diabetes and blood thinners. Seek care if there’s pain, discharge, vision change, significant trauma or repeated episodes.
For expert reassurance or rapid assessment in Sydney’s Eastern Suburbs, book with Bright Sight Eye Specialists.