What are the causes of spontaneous scleral hematoma?

Causes of Spontaneous Scleral Hematoma

Spontaneous scleral hematoma is most commonly caused by vascular abnormalities, coagulation disorders, systemic hypertension, and trauma, though it can occur without identifiable cause in some cases.

Primary Causes

Vascular Abnormalities

• Arteriovenous malformations (AVMs) - account for approximately 32-44% of spontaneous hemorrhages 1
• Arteriovenous fistulas
• Cavernous malformations
• Aneurysms - responsible for about 34% of spontaneous hemorrhages 2
• Venous angiomas

Coagulation and Hematologic Disorders

• Thrombocytopenia (platelet count <20,000/mm³) 1
• Hemophilia and other factor deficiencies (particularly severe factor VIII deficiency) 1
• Anticoagulant therapy (warfarin, heparin)
• Antiplatelet therapy (aspirin, clopidogrel) 3
• Vitamin K deficiency
• Protein C and protein S deficiencies

Systemic Conditions

• Hypertension (more common in adults than children) 1
• Sickle cell disease 1
• Diabetes mellitus (may contribute to vascular fragility) 3, 4
• Liver disease (associated with coagulopathy) 1
• Cancer and hematologic malignancies 1

Substance Use

• Cocaine and other sympathomimetic drugs 1
• Alcohol (particularly with liver disease)

Other Causes

• Malignant tumors (hemorrhage into tumor tissue) 1
• Vasculitis or inflammatory disorders
• Spontaneous intracranial hypotension 5
• Idiopathic (no identifiable cause despite thorough evaluation)

Risk Factors

Several factors increase the risk of spontaneous scleral hematoma:

• Advanced age (vascular fragility increases with age) 3
• History of hypertension 1
• Long-term use of anticoagulants or antiplatelet agents 3
• Underlying vascular malformations
• Hematologic disorders
• Recent straining, coughing, or Valsalva maneuvers

Diagnostic Approach

When evaluating a patient with spontaneous scleral hematoma, the following diagnostic steps should be taken:

1. Detailed history:

   • Onset and progression of symptoms
   • History of trauma (even minor)
   • Medication use (anticoagulants, antiplatelets)
   • Systemic conditions (hypertension, diabetes, liver disease)
   • Substance use (cocaine, sympathomimetics)

2. Physical examination:

   • Vital signs (particularly blood pressure)
   • Complete ocular examination
   • Neurological assessment

3. Laboratory tests:

   • Complete blood count (CBC)
   • Coagulation profile (PT/INR, aPTT)
   • Liver and kidney function tests
   • Toxicology screen if substance use is suspected 1

4. Imaging studies:

   • CT or MRI to evaluate for underlying vascular abnormalities
   • Vascular imaging (CT angiography, MR angiography) if vascular malformation is suspected 1

Clinical Pearls and Pitfalls

• Even with thorough evaluation, the cause may remain unknown in a small percentage of cases
• Don't assume trauma is the cause without thorough investigation for underlying conditions
• Elderly patients on low-dose aspirin are at increased risk for spontaneous hemorrhage 3
• In younger patients without obvious risk factors, vascular malformations should be strongly suspected
• Recurrent hemorrhages warrant more extensive investigation for underlying vascular abnormalities
• Spontaneous hemorrhage in children is more likely to be associated with vascular malformations than in adults 2

Remember that prompt identification of the underlying cause is essential for appropriate management and prevention of recurrence.