Eye Health · Patient Series
You woke up with
a red patch on your eye.
It looks worse than it is.
A flat, bright red blotch on the white of the eye, no pain, normal vision. That is the classic subconjunctival hemorrhage — a tiny surface vessel that has leaked under a membrane thinner than cling film. Why it happens, how it fades, and the few situations where it deserves a proper examination.
to clear
not inside, the eye
needed
Section 01 — What You Are Looking At
A bruise you can see,
on a membrane
you never noticed.
The white of the eye is the sclera, a tough coat of collagen. Over it lies the conjunctiva: a thin, clear, slightly loose membrane carrying a fine network of small blood vessels. When one of those vessels leaks, the blood is trapped in the thin space between conjunctiva and sclera. It spreads out flat, under a transparent cover, against a white background — which is exactly why a few drops look so dramatic.
Elsewhere on the body the same leak would be a bruise hidden under opaque skin. Here it is on display. Because the blood sits on the outside of the eyeball rather than inside it, it does not cloud the cornea or reach the retina, and in a simple spontaneous bleed it does not change how well you see.
A subconjunctival hemorrhage is blood trapped under the conjunctiva, the clear skin over the white of the eye. It is flat, sharply edged and bright red, usually painless, and it does not affect vision. Most are spontaneous or follow a pressure spike such as coughing, sneezing, vomiting or straining; risk rises with age, high blood pressure, diabetes and blood-thinning medicines. No treatment speeds it up: it is reabsorbed over roughly one to three weeks, changing colour like a bruise. It needs an eye examination if it follows an injury, comes with pain or blurred vision, recurs, or appears alongside unusual bleeding elsewhere.
Section 02 — Interactive
How the patch fades,
day by day.
Nothing has to be done for the blood to clear: the body breaks it down and reabsorbs it, the way a skin bruise resolves. Move the slider to see the typical arc of a moderate bleed, from bright red at the start to a faint yellow tinge before it disappears.
Two features of the timeline surprise people. First, the patch can look a little bigger on the second day than the first, as the blood spreads through the loose tissue and gravity draws it downward; that spread on its own is not a sign of a new bleed. Second, the colour change from red towards orange, yellow or faint green is haemoglobin being broken down into pigment by-products before it is cleared — the same chemistry that turns a skin bruise yellow at the edges.
Section 03 — Causes & Risk Factors
Often there is
no single reason.
Sometimes there is.
Many bleeds are spontaneous: a fragile vessel gives way and the patch is noticed by someone else, or in the mirror in the morning. When a trigger is identified, it usually falls into one of a few groups.
| Trigger or risk factor | How it contributes | Worth doing |
|---|---|---|
| Pressure spikes — coughing, sneezing, vomiting, straining, heavy lifting | A sudden rise in venous pressure (a Valsalva-type effort) can rupture a small conjunctival vessel | Nothing for the eye; treat a persistent cough or constipation |
| Minor surface trauma — rubbing, contact lens handling, a poke | Direct mechanical stress on the loose conjunctiva | Pause lenses until comfortable; be examined if there was a real impact |
| High blood pressure | Repeatedly reported as associated, especially in older adults | Have blood pressure measured |
| Blood-thinning medicines — warfarin, DOACs, aspirin, clopidogrel | Make bleeds more likely and sometimes larger | Tell the prescriber; do not stop the medicine yourself |
| Diabetes, vascular disease, ageing | More fragile small vessels | Routine management of the underlying condition |
| Conjunctivochalasis — loose, redundant conjunctiva | Folds of lax tissue are more easily traumatised by blinking and rubbing | An eye examination if bleeds recur |
| Eye procedures — anaesthetic blocks, intravitreal injections, refractive laser suction | An expected, usually harmless local effect | Nothing in most cases; mention it at follow-up |
| Bleeding or clotting disorders | Uncommon, but can present this way | Blood tests if bleeds recur or there is bleeding elsewhere |
The published risk-factor picture is consistent. Tarlan and Kiratli’s 2013 review in Clinical Ophthalmology grouped the causes into local ones (trauma, contact lens wear, conjunctivochalasis, ocular surgery) and systemic ones (hypertension, diabetes, bleeding tendency and anticoagulant use), with age as the common thread. A nationwide Taiwanese study by Hu and colleagues in PLoS One (2015) likewise reported incidence rising with age alongside associations with systemic vascular conditions, and Mimura and colleagues described the link with conjunctivochalasis in Ophthalmology in 2009 — a reminder that the state of the eye’s own surface matters as well as the blood vessels.
Section 04 — Red Flags
When a red eye
is not a simple
subconjunctival bleed.
The reassuring description above applies to one specific picture: flat, painless, sharply edged blood on the white of the eye, normal vision, and no significant injury. Change any part of that picture and the advice changes.
| Feature | Why it matters | What to do |
|---|---|---|
| Followed an injury — a blow, a fall, a projectile, hammering metal | Surface blood can hide damage underneath, including a penetrating injury | Same-day eye examination |
| Swollen blood all the way round the cornea after trauma | Extensive, raised hemorrhage after injury raises concern for an open globe | Emergency care; do not press on the eye |
| No visible back edge after a head injury | Blood may be tracking forward from the orbit or skull base rather than a local surface bleed | Emergency assessment |
| Pain, light sensitivity, reduced vision | Not features of a simple bleed; suggest inflammation, raised pressure or deeper injury | Prompt examination |
| Discharge, both eyes red, scattered small bleeds | Some viral conjunctivitis (acute hemorrhagic conjunctivitis) causes small hemorrhages | See a doctor; hygiene to avoid spreading it |
| Recurrent bleeds, or easy bruising, gum or nose bleeds | Possible blood pressure, clotting or medication problem | Blood pressure check and blood tests |
| An infant beyond the newborn period | Small bleeds are common after birth and fade, but later unexplained eye hemorrhage in a baby needs careful assessment | Paediatric review |
Section 05 — What Actually Helps
The treatment is
mostly leaving it alone.
For a simple bleed, the useful steps are about comfort and about the rest of the body, not about the patch itself.
a small bleed to clear
take this long
clear it faster
A man in his early sixties notices a bright red patch on the outer white of his right eye after a week of heavy coughing. The eye is comfortable, his vision is unchanged and nothing has struck it. His doctor confirms the picture fits a subconjunctival hemorrhage, suggests lubricating drops for comfort — and takes a blood pressure reading, which is higher than it should be. The patch is yellowing by the second week and gone within about two and a half. The eye needed nothing; the blood pressure needed follow-up.
Section 06 — After Eye Surgery or Injections
A red patch after
a procedure is usually
an expected side effect.
Subconjunctival bleeding is one of the most common things patients notice after eye procedures, and one of the least significant. It often follows the local anaesthetic given around the eye for cataract surgery, intravitreal injections for macular disease, and the suction ring used in some refractive laser procedures.
It looks alarming in the mirror the next morning, but it follows the same course as a spontaneous bleed and does not affect the result of the operation. What matters after surgery is a different list: increasing pain, worsening vision, increasing redness or discharge in the days afterwards can indicate inflammation or infection, and should be reported to the surgical team the same day rather than waited out. The week-by-week cataract recovery guide sets out what is normal at each stage.
Section 07 — FAQ
Frequently asked questions
about subconjunctival hemorrhage.
It is a small bleed from a tiny blood vessel under the conjunctiva, the thin clear membrane covering the white of the eye. The blood is trapped between the conjunctiva and the sclera, so it shows as a flat, sharply edged bright red patch. It sits on the surface of the eye, not inside it, which is why it usually does not affect vision.
On its own, usually not. A spontaneous bleed with no pain, no change in vision and no injury is typically harmless and clears without treatment. It needs prompt examination if it followed an injury, if the eye is painful or vision is reduced, if it keeps recurring, or if you also have unusual bruising or bleeding elsewhere.
Most clear within about one to two weeks; larger bleeds can take two to three weeks. The patch can look slightly larger in the first day or two, then changes colour from red towards orange-yellow as the blood is broken down and reabsorbed, much like a bruise on the skin.
Often nothing identifiable. Common triggers are sudden pressure spikes from coughing, sneezing, vomiting, straining or heavy lifting, minor rubbing or contact lens handling, and eye procedures such as anaesthetic blocks and intravitreal injections. Risk is higher with age, high blood pressure, diabetes and blood-thinning medicines.
High blood pressure is one of the associations most consistently reported in studies of these bleeds, particularly in older adults. A single bleed does not prove you have hypertension, but having your blood pressure checked afterwards is a sensible, low-cost step, especially if the bleeds recur.
Do not stop or change an anticoagulant or antiplatelet medicine on your own. These medicines make such bleeds more likely and sometimes larger, but the bleed itself is usually harmless while stopping the drug can carry serious risk. Tell the doctor who prescribes it; if you take warfarin, they may want an INR check.
No drop has been shown to speed up reabsorption of the blood. Lubricating drops (artificial tears) can ease the mild scratchy feeling some people notice, and redness-relief drops do not remove the blood. Avoid rubbing the eye, and see a doctor if it becomes painful or sticky or your vision changes.
References & Evidence Base
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