Tanya Huff goofed a little bit with the glasses thing when she was writing the books (I know this because she mentioned it herself, either in one of her LJ entries -- she's andpuff -- or when she was blogging about the show for Lifetime). They don't help with retinitis pigmentosa, so there was a line added in for the series (I think it was during the premiere, when Vicki's meeting Henry) about Vicki also being near-sighted.