Further to what Linda said with the painted over glasses.
Vision impairment is more than just total loss of sight.
Some of my suggestions would be to just leave a pin hole in the glasses to simulate keyhole vision or leave the sides unpainted for peripheral vision or paint like vertical blinds or smear the lense with vaseline so everything is blurry and just the outlines of objects can be seen through the fog. Lots of hours of learning with these 'games'. Vision impairment is more than just total loss of sight. Lots of hours of learning with these 'games'.