Subconjunctival bleeding

Subconjunctival bleeding, also known as subconjunctival hemorrhage, is a common and typically benign condition in which a small blood vessel ruptures beneath the conjunctiva—the thin, transparent membrane covering the white part of the eye (sclera) and lining the eyelids—resulting in a bright red patch of blood that becomes visible on the eye's surface.^[1] This leakage of blood is analogous to a bruise on the skin and does not usually cause pain, affect vision, or lead to discharge, though it may produce mild irritation or a gritty sensation. The condition is self-limiting, with the body gradually reabsorbing the trapped blood over 7 to 14 days, often changing color from red to yellow-green as it heals without any intervention.^[1] The hallmark symptom of subconjunctival bleeding is the sudden onset of a flat, red spot on the sclera, which may expand slightly over the first day but remains confined to the conjunctival layer and does not spread into the cornea or affect eye function.^[2] Unlike more serious eye conditions, it rarely involves swelling, light sensitivity, or blurred vision, though patients may notice the cosmetic appearance alarming.^[3] In cases involving both eyes or larger areas, underlying factors should be evaluated, but isolated incidents are generally harmless.^[4] Subconjunctival bleeding often results from spontaneous rupture due to sudden increases in intraocular or venous pressure, such as from forceful coughing, sneezing, vomiting, straining during bowel movements, or heavy lifting.^[1] Other triggers include minor eye trauma, vigorous eye rubbing, or contact lens insertion/removal, while systemic risk factors encompass hypertension, diabetes, blood clotting disorders, and use of anticoagulant medications like warfarin or aspirin.^[2] It affects people of all ages but is more common in adults over 50, with no strong gender preference, and recurrent episodes may signal an underlying coagulopathy or vascular issue requiring medical attention.^[4] Diagnosis is primarily clinical, relying on the characteristic appearance during a slit-lamp or direct eye examination, with no routine imaging or lab tests needed for uncomplicated cases.^[2] Treatment is supportive and rarely required, consisting of artificial tears to alleviate any discomfort and reassurance about the benign nature; the red patch fades naturally without scarring.^[5] Patients should seek prompt evaluation if the bleeding recurs frequently, accompanies eye pain, vision loss, or trauma, or occurs alongside easy bruising elsewhere, as these may indicate serious conditions like hypertension or bleeding diatheses. Complications are uncommon but can include cosmetic concerns or, rarely, secondary infection if associated with trauma.^[6]

Background

Definition and Overview

Subconjunctival bleeding, also known as subconjunctival hemorrhage, is a benign ocular condition characterized by the extravasation of blood from ruptured small vessels beneath the conjunctiva, the transparent membrane covering the sclera (the white part of the eye), resulting in a sharply demarcated bright red patch that does not affect vision.^[2]^[7] This condition is typically painless and self-limiting, resolving spontaneously within 1 to 2 weeks as the body reabsorbs the trapped blood, without causing discomfort or visual impairment in most cases.^[1]^[8] The basic mechanism involves the spontaneous rupture of fragile conjunctival capillaries, often triggered by minor increases in intraocular or vascular pressure, leading to hemorrhage that accumulates in the subconjunctival space between the bulbar conjunctiva and the underlying sclera or Tenon capsule.^[2] This bleeding is confined to the surface by the conjunctiva's anatomical attachments, preventing spread into deeper eye structures and limiting the lesion's extent, which appears fixed and does not blanch under pressure.^[2]^[7] Modern medical understanding recognizes subconjunctival bleeding as a common, harmless event, with recognition of its self-resolving nature dating to established clinical observations in the 20th century.^[9] Unlike more serious intraocular bleeds, subconjunctival bleeding remains superficial and does not enter the anterior chamber or vitreous, distinguishing it from hyphema—where blood pools in the anterior chamber, often causing pain, photophobia, and visible layering—or vitreous hemorrhage, which involves bleeding into the vitreous humor and leads to floaters or vision loss due to deeper vascular or retinal involvement.^[2]^[10] This superficial confinement underscores its benign prognosis compared to these potentially vision-threatening conditions.^[11]

Anatomy of the Eye Involved

The conjunctiva is a thin, transparent mucous membrane that covers the anterior portion of the sclera and lines the inner surface of the eyelids. It consists of two main parts: the bulbar conjunctiva, which overlies the sclera (the white outer layer of the eyeball), and the palpebral conjunctiva, which lines the posterior aspect of the eyelids. These regions are connected by the fornices, forming a continuous sac that allows free movement of the globe relative to the eyelids. The bulbar conjunctiva is loosely attached to the underlying sclera via Tenon's capsule, a fibrous layer that provides minimal adherence and permits the accumulation and pooling of fluids or blood in the potential space between the conjunctiva and sclera.^[12] The microvasculature of the conjunctiva comprises a dense network of capillaries embedded within its epithelial and substantia propria layers, facilitating nutrient exchange and immune function. This capillary bed is primarily supplied by the anterior ciliary arteries, which arise from the ophthalmic artery and nourish the bulbar conjunctiva, while the palpebral conjunctiva receives blood from the marginal tarsal and peripheral arcades derived from the internal carotid system. These vessels form interconnecting arcades at the fornices, ensuring comprehensive vascular coverage across the conjunctival surface. The superficial positioning of these capillaries directly over the avascular sclera contributes to the visibility of any extravasated blood.^[12] Several anatomical barriers limit the spread of hemorrhage beyond the conjunctival surface. Firm adhesions exist at the limbus, the junction between the cornea and sclera, and along the fornices, which anchor the conjunctiva and prevent posterior or deeper extension into the orbit. Additionally, Tenon's capsule serves as a robust fibrous barrier, confining extravasated blood to the subconjunctival space and isolating it from intraocular structures. This containment ensures that bleeding remains superficial and self-limited.^[2] Under normal conditions, the conjunctival vessels are thin-walled capillaries, often consisting of a single endothelial layer without smooth muscle, making them inherently fragile and susceptible to rupture from even modest increases in intravascular pressure. This physiological design supports rapid diffusion for lubrication and defense but renders the vessels prone to leakage during hemodynamic stress.^[12]

Causes and Risk Factors

Common Causes

Subconjunctival bleeding typically arises from the rupture of fragile capillaries in the conjunctiva, often triggered by mechanical stress, pressure fluctuations, or vessel wall vulnerabilities. These etiological factors lead to localized hemorrhage without deeper ocular involvement, distinguishing it from more severe intraocular bleeds. While many cases are idiopathic, identifiable causes encompass a range of everyday and pathological events that compromise conjunctival vessel integrity. Trauma represents one of the most prevalent mechanisms, where direct mechanical forces cause immediate vessel rupture. Common examples include vigorous eye rubbing, which exerts localized pressure on the conjunctiva, or minor injuries such as foreign body penetration or accidental poking.^[1] In younger patients, such incidents account for a significant proportion of cases, often linked to playful activities or improper contact lens handling that irritates and weakens the surface vessels.^[2] Spontaneous causes frequently involve transient elevations in episcleral venous pressure, prompting capillary breakage without external trauma. Activities like forceful coughing, sneezing, vomiting, or straining during Valsalva maneuvers—such as heavy lifting—suddenly increase intraocular or vascular pressure, leading to hemorrhage in susceptible individuals.^[9] These events are particularly common in otherwise healthy people, as the conjunctiva's avascular nature makes its overlying vessels prone to such pressure surges.^[2] Underlying medical conditions can predispose vessels to rupture by altering hemodynamics or structural integrity. Systemic hypertension elevates overall vascular pressure, straining conjunctival capillaries over time.^[13] Diabetes mellitus contributes through microvascular fragility and endothelial dysfunction, while anticoagulation therapies—such as warfarin, aspirin, or antiplatelet agents like clopidogrel—impair hemostasis and amplify bleeding tendencies.^[9] ^[2] Iatrogenic factors often stem from procedural or habitual interventions that directly or indirectly damage conjunctival vessels. Eye surgeries, including cataract procedures or intravitreal injections, can induce hemorrhage through surgical manipulation or postoperative inflammation.^[4] Similarly, prolonged or improper contact lens wear irritates the conjunctiva, fostering vessel fragility and rupture.^[2] Reports have also linked subconjunctival hemorrhage to COVID-19 vaccinations.^[7] In rare instances, infectious processes weaken conjunctival vasculature, culminating in bleeding. Acute conjunctivitis, particularly hemorrhagic variants caused by bacterial or viral agents, inflames and thins vessel walls, increasing rupture risk during the infection's peak.^[13]

Risk Factors and Epidemiology

Subconjunctival hemorrhage exhibits a higher incidence in older adults, with prevalence increasing substantially after age 65, where it accounts for up to 10% of reported eye complaints in clinical settings.^[2] Studies indicate no strong racial or ethnic predisposition, as the condition occurs across diverse populations without significant variation by race.^[14] Regarding gender, some population-based analyses show a slight predominance in males, though overall data suggest no consistent predilection.^[15] Lifestyle factors that elevate blood pressure, such as smoking and excessive alcohol consumption, can indirectly heighten the risk by exacerbating hypertension, a key contributor to vessel fragility.^[2] High-salt diets similarly contribute by promoting hypertension, thereby increasing susceptibility in at-risk individuals.^[8] Epidemiologically, subconjunctival hemorrhage affects approximately 65 per 10,000 individuals annually in general populations, representing about 3% of red eye presentations in emergency and outpatient settings.^[16]^[7] The condition is benign in over 90% of cases, often resolving spontaneously without intervention, which leads to significant underreporting as many episodes go undocumented.^[2] Associated medical conditions include bleeding disorders such as thrombocytopenia, which can manifest initially as ocular hemorrhage, and use of anticoagulants like warfarin or antiplatelet agents like aspirin, which impair clotting and elevate risk.^[2]^[17] Global variations in occurrence align with regional hypertension prevalence; incidence may vary by region, with studies reporting rates such as 60 per 10,000 in Taiwan.^[15]^[2]

Clinical Presentation

Signs and Symptoms

Subconjunctival bleeding typically presents as a sudden onset of a bright red, sharply demarcated patch on the white part of the eye (sclera), often affecting only one eye.^[1]^[8]^[2] This hemorrhage occurs when blood leaks from a small vessel beneath the conjunctiva, appearing flat or slightly raised and confined to the bulbar conjunctiva, with the patch potentially spreading over hours to days depending on the volume of blood.^[9]^[2] Most cases are asymptomatic, with patients often discovering the condition incidentally when looking in a mirror, as it causes no pain, swelling, or disruption to vision.^[1]^[8]^[9] However, some individuals may experience mild irritation, a foreign body sensation, or slight tearing due to the blood's presence under the conjunctiva.^[1]^[2]^[18] The size of the affected area varies widely, ranging from a small localized spot to coverage of nearly the entire visible sclera in cases of larger bleeds.^[8]^[9] Over time, the appearance evolves as the body resorbs the blood: the initial bright red hue darkens and transitions to yellow-green within 1 to 2 weeks, similar to the fading of a bruise, before fully resolving.^[2]^[18] Associated findings are minimal, with no photophobia, discharge, or pupillary changes in uncomplicated cases, though secondary irritation from dryness may occasionally occur.^[1]^[2]

Complications

Subconjunctival bleeding is typically benign with rare complications, but certain adverse outcomes can occur, particularly in cases involving underlying conditions or trauma.^[2]^[1] Recurrence affects approximately 10% of individuals, with a higher likelihood in those with underlying coagulopathies such as thrombocytopenia or those on anticoagulant therapy, potentially leading to repeated episodes that necessitate evaluation for systemic disorders like leukemia.^[2] The visible red patch can cause significant cosmetic concerns and psychological distress due to its striking appearance, particularly for individuals in professions where eye visibility is prominent, such as public speaking or customer-facing roles, despite no impact on visual function.^[2]^[9] As an indicator of undiagnosed systemic issues, subconjunctival bleeding warrants monitoring for conditions such as hypertension or bleeding disorders, especially if recurrent, to identify and manage potential underlying health risks.^[2]^[1]^[9]

Diagnosis

Physical Examination

The physical examination for subconjunctival bleeding begins with a thorough visual inspection of the eye to confirm the characteristic bright red patch on the sclera, which is sharply demarcated and typically painless.^[2] A penlight or slit-lamp biomicroscopy is employed to evaluate the extent, location, and borders of the hemorrhage, distinguishing it from deeper ciliary injection or other patterns such as circumcorneal flush that may indicate intraocular inflammation.^[2]^[19] This inspection also assesses for signs of deeper involvement. Slit-lamp examination can help exclude foreign bodies.^[2] Palpation involves gentle manipulation of the eyelids and surrounding areas to check for tenderness, which is absent in uncomplicated subconjunctival bleeding but may suggest alternative diagnoses like scleritis if present. Eyelid eversion may be performed to inspect the palpebral conjunctiva and fornices for evidence of foreign bodies or trauma-related signs.^[19] Vital signs, particularly blood pressure, are measured during the examination to identify potential contributions from hypertension, especially in cases of spontaneous or recurrent bleeding.^[2]^[5] Intraocular pressure should be assessed via tonometry to ensure normal values and rule out associated conditions.^[2] Ocular motility testing evaluates extraocular muscle function for any restriction, while visual acuity assessment ensures no impairment, as subconjunctival bleeding alone does not typically affect vision or cause ophthalmoplegia.^[2]^[19] Documentation of the findings is essential, often including serial photographs of the affected eye to monitor the resolution of the hemorrhage over time and track any changes in size or appearance.^[19] This visual record aids in follow-up evaluations and helps rule out progression to more serious orbital involvement.^[2]

Differential Diagnosis

Subconjunctival hemorrhage (SCH) is often distinguished from other causes of red eye by its characteristic painless, bright red, well-demarcated patch confined to the conjunctival space, without involvement of the cornea or deeper structures.^[2] Key mimicking conditions include episcleritis, which presents with sectoral redness and mild tenderness due to inflammation of the episclera, often responsive to topical phenylephrine blanching; conjunctivitis, featuring diffuse conjunctival injection with associated discharge, itching, or foreign body sensation and frequently bilateral involvement; and pterygium or pinguecula, which appear as elevated vascular growths or yellowish plaques on the conjunctiva, typically asymptomatic but potentially inflamed.^[2] These mimics can be differentiated through careful history and examination, as SCH lacks the tenderness, discharge, or structural elevation seen in these alternatives.^[7] More serious differentials must be ruled out, particularly in traumatic or recurrent cases, such as hyphema, where blood accumulates in the anterior chamber leading to visible layering, vision impairment, photophobia, and elevated intraocular pressure; or globe rupture, which occurs post-trauma with severe pain, proptosis, chemosis, and potential vision loss from ocular penetration.^[2] Diagnostic clues favoring SCH include the absence of pain, preserved visual acuity, and no pupillary abnormalities or intraocular involvement on slit-lamp examination, whereas fluorescein staining can help exclude corneal erosions or abrasions if superficial irregularities are suspected.^[7] Escalation to further investigation is warranted for bilateral SCH, recurrent episodes, or associated systemic bruising, which may indicate underlying coagulopathy such as thrombocytopenia or anticoagulant effects.^[2] In cases with trauma history or suspicion of deeper pathology, tonometry should be performed to assess intraocular pressure, as elevated readings may suggest hyphema or angle recession rather than isolated SCH.^[7] Persistent or nodular lesions require anterior segment imaging or biopsy to exclude vascular tumors like hemangiomas or Kaposi sarcoma.^[2]

Management and Prognosis

Treatment Approaches

Subconjunctival bleeding is typically a self-limiting condition that resolves spontaneously without specific intervention, as the hemorrhage absorbs naturally over time. Most cases clear within 7 to 14 days, though larger hemorrhages may take up to 1 to 4 weeks.^[2]^[19] Conservative management focuses on observation and patient reassurance to alleviate concerns about the benign nature of the condition. No medical or surgical treatments are required for uncomplicated cases, and patients are advised to avoid activities that could exacerbate bleeding, such as rubbing the eye or engaging in strenuous exercise.^[9]^[2] For symptom relief, artificial tears or lubricating eye drops can be used to address any mild irritation or dryness caused by the hemorrhage disrupting the tear film. These drops provide comfort but do not influence the resolution timeline. Patients should also refrain from wearing contact lenses until the hemorrhage fully resolves to prevent further irritation.^[9]^[19] When an underlying cause is identified, management involves addressing it to prevent recurrence. For instance, in hypertensive patients, controlling blood pressure through lifestyle modifications or medications is recommended. Similarly, for those on anticoagulant or antiplatelet therapy (such as aspirin or warfarin), consultation with a physician to review and potentially adjust the regimen is advised, particularly if episodes are recurrent. Topical steroids or antibiotics are not routinely used unless there is concurrent conjunctivitis.^[2]^[19] Interventional approaches are rarely needed and reserved for persistent, recurrent, or atypical cases. Surgical intervention is not indicated for standard subconjunctival bleeding, though in scenarios involving trauma with extensive hemorrhage, imaging or exploration may be considered to rule out deeper injury.^[2]^[19] Follow-up is generally unnecessary for isolated episodes but involves re-evaluation if the hemorrhage does not improve within 2 to 3 weeks, persists beyond 4 weeks, or if new symptoms such as pain, vision changes, or recurrence develop, prompting assessment for systemic conditions.^[2]^[19]

Prognosis and Prevention

The prognosis for subconjunctival bleeding is excellent in uncomplicated cases, with the hemorrhage typically resolving spontaneously within 10 to 14 days as the body absorbs the trapped blood, leaving no scarring or impact on vision.^[2]^[8] During healing, the affected area may temporarily appear yellowish as the blood breaks down, but this does not affect visual function or require intervention beyond symptom relief if needed.^[1] Recurrence rates are low, affecting approximately 5% to 10% of individuals without identifiable risk factors, though the risk increases if underlying conditions such as hypertension or use of anticoagulants persist, necessitating monitoring for systemic associations.^[2]^[8] Frequent recurrences warrant evaluation to rule out treatable contributors. Prevention strategies focus on addressing modifiable risk factors, particularly managing hypertension through lifestyle modifications and medication adherence to reduce vascular stress.^[1] Individuals should avoid activities that involve significant straining, such as heavy lifting or intense coughing during high-risk periods like flu season, and wear protective eyewear during sports or hazardous work to minimize trauma.^[9] For contact lens users, maintaining strict hygiene protocols is essential to prevent irritation-related episodes.^[8] Lifestyle advice includes practicing gentle eye care by avoiding vigorous rubbing and using preservative-free artificial tears to alleviate dryness, alongside regular medical check-ups for at-risk groups such as those with diabetes or bleeding disorders.^[5] Patients experiencing red flags like eye pain, vision changes, or recurrent episodes should seek prompt medical attention, as these may signal non-benign underlying issues requiring further assessment.^[9]^[2]