A patient admitted after a severe crush injury to the chest develops bilateral blurred vision. Fundoscopy shows multiple cotton-wool spots and superficial intraretinal haemorrhages clustered around both optic discs, with macular sparing. What is the underlying mechanism?

• A Microvascular occlusion from fat or air emboli and raised venous pressure ✓
• B Direct mechanical contusion of the retina
• C Vitreous traction at the vitreoretinal interface
• D Choroidal rupture with secondary subretinal haemorrhage

Explanation

Purtscher retinopathy follows severe compressive thoracic or head trauma. Sudden raised intrathoracic venous pressure combined with fat, air, or platelet microemboli occludes precapillary arterioles, producing peripapillary cotton-wool spots and intraretinal haemorrhages with a characteristic area of spared pericapillary retina. Direct contusion gives unilateral changes at the site of impact, and choroidal rupture produces crescentic breaks, neither of which matches bilateral peripapillary lesions.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.