That would be so interesting! If he were still a werewolf and an alpha, you could do some great exploration of how his lack of sight would affect his role as a leader. Plus, him compensating for his blindness by honing his other senses would be neat!
the idea would be that werewolf powers manifest around the same age that they lose their baby teeth. when Derek was still a newborn, he had a visual defect, I think it’s called coloboma?, but because of his heightened senses and the fact that werewolves usually don’t need to go to the doctor that often, they did not see it in time to prevent it. by the time it was detected, his powers had manifested and any surgery attempted would be practically impossible because his body would constantly try to heal anything they surgically altered to fix his vision.
when he runs into stiles and scott, they don’t even know he’s blind because he can almost pinpoint exactly where they are because of his hearing and sense of smell being twice as enhanced as most werewolves, even.
it’s actually not until they try to get him arrested that they find out. and it’s because stiles’ dad is like ‘as much as I’d like to believe you, son, Derek Hale is blind. I’m not saying blind people are incapable of murder—but in this case, I can tell you he wouldn’t have been able to do it.’
Stiles doesn’t believe his dad, of course. Derek looked right at him and Scott in the woods, after all.
it isn’t until Derek shows up at school, bleeding and pale, and Stiles has to help him that he figures it out. It’s not even because Derek acts vulnerable—though he does forcefully latch on to Stiles when they get to the clinic and lets Stiles guide him around—, but it’s because his stare is unfocused. He can lock onto Stiles’ face but his eyes don’t connect to anything. It’s like a blank gaze in his direction.