aetiology

Last reviewed 01/2018

mechanisms of vitreous haemorrhage
  • vitreous haemorrhage may be caused by the following mechanisms:
    • retinal vessels that are vulnerable to bleeding
    • rupture of normal retinal vessels due to stress
    • extension of blood from an adjoining source
  • abnormal retinal blood vessels prone to bleeding :
    • occurs as a result of neovascularization in response to ischemia
    • is induced by vascular endothelial growth factor (VEGF), etc
    • is seen in diseases such as:
      • diabetic retinopathy
      • sickle cell retinopathy
      • retinal vein occlusion
      • retinopathy of prematurity
      • ocular ischemic syndrome
    • these newly formed vessels:
      • are fragile
      • are prone to spontaneous bleeding
      • can rupture due to vitreous traction that occurs with usual movements of the eye
  • rupture of normal vessels
    • occurs when mechanical force is greater than their structural integrity
      • e.g posterior vitreous detachment with or without a retinal tear or detachment
      • retinal detachment
    • can be caused by direct injury to intact vessels
      • trauma (blunt /perforating)
      • main cause in age less than 40
    • may be associated with Terson’s syndrome
      • a rare cause
      • associated with subarachnoid hemorrhage
      • sudden increase in intracranial pressure can cause retinal venules to rupture
  • extension of blood through the internal limiting membrane into the vitreous from an adjoining source
    • these hemorrhages may arise from :
      • macroaneurysms of the retina
      • choroidal neovascularization
      • tumors

Reference:

(1) John P Berdahl, et al, vitreous hemorrhage: diagnosis and treatment,eye net magazine, © American Academy of Ophthalmology, 2007