I have been perfectly blind in a few lucid dreams. I could feel my self "enter the dream ( through a WILD) and I knew 100% I was dreaming but I couldn't see anything ( after HI, I felt my self standing upright, and I heard some stuff.) I couldn't open my eyes! What I found somewhere else is:

Your eyes are glued shut ( that's what it felt like). Just use your hands, and pry them open. Either rub them to get the "glue" off or open then like, for real.

I tried it, and it worked. It was a long time ago, but techniques don't age.