I depend on my eyeglasses to see clearly, without them I literally can't make out much of anything, it's just a big blur. How did cavemen and people in history before eyeglasses were available manage to see without prescription eyeglasses if they had poor to horrible vision. Were they rendered useless or considered handicap, maybe even thought of as going blind?

They didn't. They were blind. On the bright side, they didn't have to read or drive, so possibly didn't even notice, if the condition wasn't too bad. But, on the down side, they couldn't see the saber-toothed tiger lurking behind those bushes. Ahhhhhhhhhh!