This cats name is Matilda and she has a genetic disorder called spontaneous lens luxation which has caused her eyes to become enlarged, glassy alien eyes. She has her very own website where her owners assure that she is being well cared for and regularly checked by a vet to make sure she is not in any pain from her condition.
Despite the otherworldy look of her eyes, she is not from outer space as far as her owners can tell. They should probably try to stay on her good side anyway... just in case.