My husband lost sight in his left eye during valve replacement surgery -- blood clot travelled to eye. any hope?

Embolism: I'm so sorry to hear this. Unfortunately this is an ocular emergency when it occurs and the visual outcomes are almost always devastatingly poor. The arterial embolism traveled from the heart to the artery of the eye and lodged blocking blood flow. Depending on where along the path the blockage is, the vision can be totally gone (proximal or ophthalmic artery) to partially gone if inside the eye.

Unlikely: This is a known risk of aortic or mitral valve surgery. It may be a blood clot or a plaque that broke off.

Artery occlusion: Unfortunately there was most likely a retinal artery occlusion or ischemic optic neuropathy of the eye during the surgery. A small plaque or clot may have broken off the heart valve and lodged in the retinal artery. Once obstruction of blood flow has been present for more than about 100 minutes, the damage may be irreversible. It is possible that recovery may come from nearby uninvolved tissues.