Pigeons can be born missing an eye or completely blind, or they can lose an eye or their sight as a result of accident or disease or be born with one eye unformed. Either way, like other blind animals they adapt and lead happy lives if they are given the chance.
Pigeons with an eye injury will need to be examined by a vet to determine as they might need antibiotics, eye drops or painkillers.
Technically one eyed pigeons are releasable as the limitation to their vision does not prevent them from finding food or picking it up. However, being blind in one eye makes them more vulnerable to predators, traffic and malice as they can so easily be blindsided, so if they can be found a home as a pet or at a sanctuary, that is the best option for them.