I think my dog was abused?

It sounds like she could have been abused. The owner before her could have been an older man. Sadly previous generations beat dogs that didn't behave. I had a cat who was born completely blind. So yes she could have been born blind. But does the eye and surrounding area have scaring? If so then it may have been caused by abused. Look at the eyeball. A born blind eye will look different than a damaged blind eye.