I was blind but now I see

....
It does for some people (like me).

Actually my eyes is quite bad so whenever someone took my glasses, everything is blurry for me though.

I need glasses as well. However even if my vision is blurry, I can basically still make out the general shape and colour of somthing, especially if it's right in front of me. But in some mangas they make it look like the character wearing the glasses can't see AT ALL without them. Example: they constantly bump into things or need guidance even in familiar places. I mean glasses "only" sharpen your eye sight but they can't create vision.

Maybe he thought his vision is quite bad? Because in my case, I can recognize something's shape only if it's 20 cm in front of my eyes o.o''

But well, I agree the blind part though.

True, I only bump into stuff in the dark (my night vision is horrible) even with my glasses on. I have never been in public or on a street with my glasses off. So I dunno how realistic it is to bump into things or need guidance there. I imagine I may bump into people though (because of the blur and my depth perception). Indeed, I think those manga exaggerate because it is a chance for bonding if one character is guiding another. I think moments when the character says they can't see their partner well during sex or something is realistic though. Like in this manga, I wouldn't be able to see his nipple unless it was 4 inches from my face. It'd just be a fuzzy blur of darker color otherwise. (They did mention his nipple right? I can't remember...)

Last time my glasses broke to the point that they were ruined I had to have some one lead me around by my hand. My depth perception was completely non existent and I could not judge were the curb was nor see any obstruction in my path. Without my glasses I can see about a hand span away without it being blurry. A few feet away and it becomes light and shadows and vague colored shapes.