Over the past few days we've noticed one of my cats (18 years) stumbling around slowly and occasionally bumping into things. They were too far appart for us to suspect anything though. Today she has totally gone from bad to worse. She can't see anything and she's walking into everything and getting lost around the house, crying for us to come help her. We would take her to the vets but they're closed for the New Year. We've noticed her pupils aren't dilating and they're cloudy. Any advice? And also she has an overactive thyroid gland. Is the blindness anything to do with this or is it just old age?