My Boston's eye

What would be the cause of one of my dogs eyes (the right eye pictured) having a bluish cloudy look in it out of nowhere? The other eye is fine. I have a pic I'd like to show. She is 9

Hello - I can't see your picture,  but the first thing to say is that eye changes are often emergencies, so its worth getting this triaged (calling your vet and having them trot through the symptoms with you, to see whether you should be seen now, or tomorrow morning, or sometime in the next few weeks).  Possibilities could range from the severe to the mild, including glaucoma, foreign bodies, uveitis, corneal ulcer, and so on.  I hope that something there is helpful.