What's the point of making him blind if he can see with his glasses anyway? Is it just an easy way to create drama and tension now and again?
Slightly off-topic, but I had the same problem with Daredevil, when they revealed that, even though he is blind, he sees the world as 'a world of fire', which would have been a nice symbolic way of putting it, but then they actually show the world from his point of view. Turns out he can actually see the environment he's standing in, with all the objects and people in it, but everything is made of fire.
That was so dumb to me. Here's a cool thing - a show about a blind guy being a superhero (including a very well done alternate audio track for blind people). Such a cool thing for blind kids/teens watching. And then he's not
really blind. That was a bummer to me. Although I don't think they ever brought it up again later, although I can't remember now if I ever finished all the episodes.
As for the Doctor's blindness - I kinda have the same problem here. But even when it was revealed his bilndness would carry over to other episodes, I was sure it would be cured before the end of the season. I would be very surprised if he's blind all the way to his regeneration scene.
Which would have been cool, but yeah. I do think they managed to get some good story beats out of his blindness, especially in relation to his lying to Bill (and Nardole doing a very bad but effective job of covering up for him), but I don't know if the x ray function on the glasses was needed either. It seems he can see now again so it won't happen, but I kept waiting for those little age/sex/heart beat/whatever indicators whenever he sees people to be used for a reveal. Something like: 2 hearts? Missy! Wait, 16 years old? Susan?
Or something better, I'm no writer.