Visual loss after shoulder surgery under general anesthesia diagnosed as caused by ocular compression with electroretinography testing: case report and review of the literature.

Ophthalmic complications after nonocular surgery are well documented in the ophthalmic, surgical, and anesthesia literature. A case of unilateral visual loss after shoulder surgery under general anesthesia is presented in which electroretinography (ERG) confirms ocular compression as the etiology of the visual loss. Compression is a preventable risk factor for perioperative visual loss, and its diagnosis has serious medico-legal implications. The importance of performing ERG testing in all unexplained cases of visual loss after nonocular surgical procedures is supported by this case to rule out ocular compression perioperatively. The abnormal decreased scotopic ERG B-wave amplitude in the affected eye compared with the normal eye confirms ocular compression, which can be prevented by proper positioning of the head and adequate headrest during general anesthesia.