Commotio retinae is caused by which mechanism?

• A. Coup/counter-coup injury
• B. Direct retinal tear
• C. Chronic hypertension
• D. Age-related macular degeneration

Answer: (A)

Blunt trauma to the eye causes the globe to deform rapidly, creating shear forces within the retina that disrupt the photoreceptor outer segments and the retinal pigment epithelium. This rapid acceleration–deceleration injury is classically described as coup/countercoup, where the impact site (coup) and the opposite side (countercoup) experience stress, leading to the characteristic retinal whitening of commotio retinae. It’s an acute mechanical injury to the retina, not a tear from a direct focal hit, nor caused by systemic conditions like hypertension or degenerative diseases such as AMD.