possibly blind

Hi....I found a pigeon. Seems to be blind in both eyes. What do you think is the cause for its blindness? Is it a disease or someone injured it? Is it permanently blind? I also have 2 cockatiels (which I am keeping separate), so I hope it's nothing contagious. If it's an injury, any ideas how...

I feel like I'm posting an awful lot lately, but I can't get over how excited I am to have other people to talk to about my birds now as well as having them. Anyway, I hope I am on the right thread, and I figured I'd have my best chance of finding others with similar experiences on this one...