Recently an English man was diagnosed with superior canal dehiscence syndrome after 6 months of progressive hearing loss, eventually cumulating in hearing his heart beat and hearing his eyes move 1. This is due to internal damage to the ear, which means internal noises can be heard, like the friction of the muscles moving in the eyes. It has an incidence of 1 in 500,000. Luckily, once diagnosed the operation was relatively straight forward.
E Markham (2011). Ocular Oddity Blogspot