Large recession of the four vertical rectus muscles for acquired pendular vertical nystagmus and oscillopsia without a null zone.

A 55-year-old man presenting with acquired pendular vertical nystagmus without a null zone was treated with large recessions of the four vertical rectus muscles. Nystagmus and oscillopsia were greatly reduced after surgery. Associated lid nystagmus persisted after surgery, suggesting that treatment success was caused by mechanical weakening of the muscles rather than by interruption of a proprioceptive feedback loop.