What is the cause of subconjunctival hemorrhage?

Causes of Subconjunctival Hemorrhage

Subconjunctival hemorrhage most commonly results from minor local trauma, viral conjunctivitis, systemic hypertension, and anticoagulation therapy, with the vast majority being benign and self-limited. 1, 2

Primary Etiologies

Common Benign Causes

• Minor local trauma is the most frequent cause, particularly in younger patients and shows seasonal variation with increased incidence in summer 2
• Viral conjunctivitis, especially adenoviral infection, frequently presents with petechial and subconjunctival hemorrhage as a distinctive clinical sign 3, 1
• Systemic hypertension is a major cause, particularly in older patients, and blood pressure should be checked in all patients presenting with subconjunctival hemorrhage 2
• Acute conjunctivitis of any etiology can produce subconjunctival hemorrhage 2

Medication-Related Causes

• Anticoagulation therapy (warfarin and direct oral anticoagulants) is an important medication-related cause that can produce recurrent, bilateral, and severe hemorrhages 1, 4
• Prolonged prothrombin time from oral anticoagulation can lead to severe subconjunctival and external hemorrhage from the eye 4

Infectious Causes Beyond Common Conjunctivitis

• Epstein-Barr virus can present with hemorrhagic conjunctivitis including subconjunctival hemorrhage and periorbital edema 1
• Measles (rubeola) causes bilateral subconjunctival hemorrhages along with other conjunctival findings 1

Valsalva-Related Causes

• Increased intrathoracic pressure from repetitive vomiting or coughing spells can cause recurrent hemorrhages 4
• Positional asphyxia, particularly head-down positions, can produce extensive subconjunctival bleeding (hyposphagma) through hemodynamic dysregulation and decreased venous return 5

When to Suspect Serious Underlying Disease

Red Flags Requiring Further Investigation

• Recurrent subconjunctival hemorrhage without identifiable cause warrants further workup 1
• Bilateral and severe hemorrhages mandate search for underlying blood dyscrasia or clotting disorder 4
• Associated conjunctival nodules or masses require biopsy to exclude malignancy 1

Malignant Causes (Rare but Important)

• Ocular adnexal lymphoma may initially present as recurrent subconjunctival hemorrhage with characteristic salmon-pink conjunctival lesion 1
• Sebaceous carcinoma can appear as yellowish discoloration with subconjunctival multilobulated yellow mass 1
• Conjunctival melanoma presents as painless brown or fleshy-pink lesions 1

Important Clinical Caveats

Bleeding Disorders Are NOT a Common Cause

• Routine hemostatic screening is not indicated for spontaneous subconjunctival hemorrhage, as the prevalence of congenital or acquired bleeding disorders is <1% and not different from the general population 6, 7
• Von Willebrand disease prevalence in patients with recurrent subconjunctival hemorrhage (3.8%) is not statistically different from the normal population 6, 7
• Hemostatic screening or second-level coagulation tests are of no use in patients with recurrent subconjunctival hemorrhage who have no other bleeding manifestations 7

Age-Related Patterns

• Older patients more commonly have hypertension-related subconjunctival hemorrhage and should have blood pressure checked 2
• Younger patients more commonly have trauma-related hemorrhages 2

Warning Signs Requiring Urgent Evaluation

• Enlargement of associated conjunctival lesions, development of blood vessels, thickening, or recurrence in the same location, especially in elderly patients 1
• Blurred vision occurring simultaneously with subconjunctival hemorrhage suggests concurrent trauma affecting other eye structures 8