Subconjunctival Hemorrhage: Causes, Symptoms, Diagnosis, and Management When Blood Appears in the Eye

Subconjunctival hemorrhage refers to bleeding beneath the conjunctiva, the thin, transparent tissue covering the sclera (white of the eye). The key visual feature is a well-demarcated, bright-red patch or stripe that may look dramatic but is often painless. The underlying mechanism is rupture of small superficial conjunctival blood vessels, leading to extravasation of blood into the subepithelial space. Because the conjunctiva has minimal sensory innervation compared with deeper ocular structures, patients frequently report no significant pain, just a conspicuous red area.

Epidemiologically, subconjunctival hemorrhage is common and typically benign. It can occur spontaneously or after minor mechanical stress. Classic precipitants include eye rubbing, coughing or sneezing, vomiting, heavy lifting/straining, contact with irritants, and episodes that transiently increase venous pressure. Systemically, it may be associated with hypertension, diabetes, bleeding diatheses, or use of medications that impair platelet function (e.g., antiplatelet agents) or coagulation (e.g., warfarin, direct oral anticoagulants). Importantly, many cases reflect vessel fragility without an identifiable systemic cause.

Clinically, the hemorrhage is usually unilateral, though bilateral episodes can occur in systemic coagulopathies. Vision is typically preserved because the bleeding is confined to the conjunctival surface and does not directly involve the cornea or posterior segment. The red area tends to evolve over days, transitioning from bright red to darker red or brownish hues, then resolving as the blood is resorbed. Healing commonly occurs within 1–2 weeks. Patients may notice mild grittiness or foreign-body sensation, but severe pain, photophobia (light sensitivity), or decreased vision are not typical and should prompt urgent evaluation.

A critical clinical distinction is between subconjunctival hemorrhage and more sight-threatening causes of red eye. If redness is accompanied by conjunctival discharge, contact lens wear with pain, corneal epithelial defects, or a circumcorneal injection pattern, clinicians must consider keratitis, uveitis, acute glaucoma, or infectious conjunctivitis. Subconjunctival hemorrhage typically lacks purulent discharge and does not cause significant discomfort. Another differential includes hyphema (blood in the anterior chamber), vitreous hemorrhage, and retinal bleeding, which carry different risks and symptom patterns.

Diagnosis is primarily clinical, based on history and slit-lamp examination. Clinicians assess: (1) location and extent of the bleed relative to the limbus and cornea, (2) presence of corneal staining, (3) anterior chamber depth and whether blood is present inside the eye, and (4) intraocular pressure when glaucoma is a concern. If recurrent hemorrhages occur, if the patient reports easy bruising, frequent epistaxis, or if there is use of anticoagulants or known coagulation disorders, additional workup may include blood pressure measurement, a review of medications, and targeted labs such as complete blood count and coagulation studies (e.g., PT/INR, aPTT) depending on clinical context.

Management is usually conservative. For uncomplicated subconjunctival hemorrhage, reassurance is appropriate, along with lubricating artificial tears if irritation occurs. Avoiding eye rubbing and addressing triggering factors (e.g., constipation/straining, management of cough, blood pressure control) may reduce recurrence. Patients on anticoagulants should not stop therapy without clinician guidance; instead, clinicians weigh thromboembolic risk versus bleeding risk and may adjust dosing or evaluate for interacting medications.

Red-flag symptoms requiring prompt ophthalmic assessment include: eye pain (especially moderate to severe), reduced visual acuity, marked photophobia, halos around lights, nausea/vomiting with red eye, contact lens–associated pain or discharge, signs of trauma, and recurrent hemorrhage over short intervals. In such cases, evaluation aims to rule out corneal ulcer, uveitis, acute angle-closure glaucoma, traumatic globe injury, and intraocular bleeding.

Prognosis is excellent in typical cases, with spontaneous resolution as the blood is reabsorbed. The primary “treatment” is appropriate risk stratification: recognizing that a conspicuous red patch can be harmless while still screening for ocular or systemic conditions that change urgency. Source: @sz_josh1