Subconjunctival haemorrhage

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

A small conjunctival vessel can rupture and allow blood to collect beneath the transparent conjunctiva. The result is a bright red area over the white of the eye, often noticed by another person or in a mirror. Unlike conjunctivitis, the main visible finding is a discrete collection of blood rather than a pattern of inflamed vessels and discharge. Confirm that the patient has normal acuity, no significant pain or photophobia, a normal pupil and no concerning corneal finding. Reassurance depends on this complete pattern, not simply on the colour of the eye.

Many episodes occur without a clear trigger. Coughing, sneezing, straining or minor rubbing may precede the event, and hypertension or medicines that affect clotting can be relevant. Ask specifically about trauma and its mechanism because a patient may initially dismiss an impact or a high-speed particle as trivial. Also ask whether this has happened before, whether bruising, gum bleeding, nosebleeds or bleeding elsewhere has increased, and whether medication doses have changed. A single local episode and recurrent bleeding with systemic symptoms require different assessments.

For a typical spontaneous episode, explain what the patient can expect. The blood is reabsorbed gradually, and its colour or distribution can change during recovery. There is usually no need for an antibiotic, steroid or procedure to remove it. A cold compress or an appropriate lubricant can be considered for minor surface irritation, but these do not accelerate blood clearance. Provide a clear route back if pain, photophobia or visual change occurs, or if the haemorrhage does not resolve in the expected period.

Key points

An uncomplicated subconjunctival haemorrhage is a sharply demarcated patch of blood under the conjunctiva with normal visual function.
The appearance can be dramatic while the eye remains comfortable; substantial pain or light sensitivity requires another explanation.
Most uncomplicated episodes clear spontaneously within one to two weeks without specific treatment.
Ask about injury, coughing or straining, anticoagulants and other bleeding, and measure blood pressure.
A first typical episode usually needs no extensive laboratory investigation, but recurrence and systemic findings change that decision.
Do not automatically stop anticoagulants or antiplatelet treatment for an isolated minor ocular surface bleed.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Spontaneous vessel rupture

A small superficial vessel may rupture without an identifiable cause. Coughing, sneezing, straining or minor rubbing can sometimes precede the appearance of the blood.

Systemic and medicine associations

Hypertension and medicines affecting haemostasis may contribute to bleeding. Recurrent episodes or bleeding elsewhere increase the relevance of reviewing these possible associations.

Traumatic haemorrhage

A blow, penetrating injury or high-speed particle can cause conjunctival bleeding. The visible patch does not establish whether the deeper ocular structures have remained intact.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Blood beneath a clear membrane
Blood accumulates under the transparent conjunctiva and remains visible against the underlying sclera. This produces a striking appearance without necessarily disturbing the optical structures.
2
Preserved ocular function
An isolated superficial collection does not involve the cornea, anterior chamber or retina. Normal vision and the absence of significant pain therefore support the uncomplicated pattern.
3
Gradual reabsorption
The collected blood is broken down and cleared over time, with possible colour changes during resolution. Topical antibiotics do not alter this physiological clearance process.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Typical benign appearance

A sharply outlined red patch beneath the conjunctiva, preserved acuity and a comfortable eye support an isolated subconjunctival haemorrhage when trauma and deeper abnormalities are absent.

Injury-related concern

A penetrating or high-velocity mechanism, marked swelling, abnormal pupil or reduced vision requires urgent assessment even if visible blood appears confined to the conjunctiva.

Recurrent or widespread bleeding

Repeated spontaneous episodes, new easy bruising or mucosal bleeding suggest a need to review systemic illness and medicines rather than treating each eye episode in isolation.

Blood-pressure and medicine context

Measure blood pressure and record anticoagulants, antiplatelets and other relevant medicines, including recent additions or dose changes that may alter bleeding risk.

Red flags requiring action

Pain, photophobia, persistent visual reduction or an abnormal pupil is inconsistent with a straightforward isolated subconjunctival haemorrhage.
A significant injury mechanism, extensive swelling or haemorrhage obscuring the extent of trauma requires urgent ophthalmic assessment.
Recurrent spontaneous episodes or bleeding elsewhere warrants a targeted medical assessment rather than repeated reassurance alone.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Visual acuity, pupil and external eye assessmentFirst step
Why
Confirm that the presentation fits a superficial isolated bleed.
Interpretation and limitations
Pain, an abnormal pupil, corneal disease or reduced acuity means reassurance alone is insufficient and may require urgent ophthalmic examination.
02
Blood pressure measurement
Why
Identify a potentially relevant and treatable systemic association.
Interpretation and limitations
An elevated measurement needs interpretation and follow-up through the appropriate blood-pressure pathway; the ocular appearance alone does not establish hypertensive emergency.
03
Medication and bleeding-history review
Why
Determine whether a medicine or wider bleeding problem contributes.
Interpretation and limitations
A stable isolated bleed differs from recurrence with other bleeding; document the indication for antithrombotic treatment before discussing any change with its prescriber.
04
Targeted blood count and coagulation assessment
Why
Investigate recurrent episodes or a concerning systemic history.
Interpretation and limitations
Select tests according to the presentation and medicines, including INR when clinically indicated for warfarin; routine testing is unnecessary for every first typical episode.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Conjunctivitis

Inflamed conjunctival vessels, irritation and watery or sticky discharge differ from a discrete blood collection. Significant visual reduction still requires assessment beyond uncomplicated conjunctivitis.

Episcleritis or scleritis

Inflammation produces vascular redness rather than simply extravasated blood. Deep pain, tenderness or reduced vision increases concern for scleral involvement and changes urgency.

Serious ocular trauma

A superficial-looking bleed may accompany globe injury, particularly after a dangerous mechanism. Pupil abnormality, visual change or marked swelling should prevent premature reassurance.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Typical isolated bleedExplain natural recovery and provide a safety netFirst stepThe eye is comfortable, vision is normal and assessment identifies no concerning injury or associated findings.

1Explain that blood has collected beneath the conjunctiva and commonly clears without treatment over one to two weeks.
2Check blood pressure and relevant medicines, and address a clear local irritant or straining trigger when feasible.
3Give return instructions for pain, photophobia, altered vision, persistent bleeding or failure to follow the expected improving course.

02Recurrent episodesLook beyond the visible eye findingThe haemorrhage recurs, persists or accompanies bruising, mucosal bleeding or a relevant medicine change.

1Review the frequency, laterality, triggers and any bleeding elsewhere, together with the full medication history.
2Arrange focused examination and appropriate laboratory testing, coordinating with the anticoagulation service or usual prescriber when relevant.
3Avoid reflex interruption of essential antithrombotic treatment; base any adjustment on bleeding severity, test results and the medicine's clinical indication.

03Trauma or atypical symptomsProtect the eye and exclude deeper injuryThere is significant trauma, pain, photophobia, visual decline or another finding inconsistent with an isolated superficial bleed.

1Clarify the mechanism and arrange urgent ophthalmic assessment without allowing the visible haemorrhage to obscure a possible serious injury.
2If penetration or rupture is suspected, avoid pressure, tonometry and attempts to remove an embedded object; protect the eye with a rigid shield.
3Communicate the mechanism, acuity where safely measured and relevant anticoagulant use to the receiving service.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Missed underlying illness

Repeated haemorrhage can be a clue to uncontrolled blood pressure, medication-related bleeding or another systemic problem. The consequence arises from failing to assess the wider pattern.

Unnecessary treatment changes

Independent withdrawal of essential antithrombotic medication can expose a patient to avoidable thrombotic risk. Medication decisions require the indication and bleeding severity to be considered together.

Delayed injury recognition

Attributing all visible blood to a benign surface event can delay diagnosis of an associated traumatic injury. A careful mechanism history and functional examination reduce this risk.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

A typical first episode can be monitored through symptom-led advice, with review if it does not clear over the expected one-to-two-week course.
Tell the patient that changing colour alone during resolution can be expected, while new pain, light sensitivity or visual decline requires prompt reassessment.
Ensure an elevated blood-pressure finding receives appropriate follow-up rather than assuming that spontaneous eye recovery resolves the medical issue.
Follow through any blood tests or anticoagulation review arranged for recurrent bleeding, recording the agreed medication plan.
When trauma is involved, follow the specialist injury plan; routine reassurance about a superficial haemorrhage is not a substitute for completing that assessment.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Appearance does not measure severity

A large visible red patch can be clinically minor, while a smaller patch after a dangerous injury mechanism can accompany serious damage. Function, symptoms and mechanism determine urgency.

Antithrombotic decisions need context

Stopping an anticoagulant or antiplatelet can remove protection against thrombosis. An isolated minor bleed should prompt appropriate assessment and advice rather than automatic withdrawal.

Recurrence changes the question

Repeated episodes justify review of blood pressure, medicines and broader bleeding symptoms. The objective is to identify a relevant contributor, not to order every possible coagulation test.

Infant findings need careful assessment

A haemorrhage in an infant or a history inconsistent with the examination requires an age-appropriate clinical assessment, including consideration of trauma and safeguarding where indicated.

11Common pitfallsFrequent interpretation and management errors.

01
Diagnosing a benign haemorrhage without checking acuity and asking about pain, light sensitivity or a high-velocity injury.
02
Starting antibiotics or steroids solely to make the visible blood disappear despite no evidence of infection or inflammation requiring treatment.
03
Advising patients to stop antithrombotic medicines independently without considering indication, severity or the prescribing team's advice.
04
Repeatedly reassuring about recurrent ocular bleeding while ignoring newly reported bruising, nosebleeds or an elevated blood-pressure reading.