In chapter 9: what do Mrs. Who's glasses enable meg to do?

Meg suddenly remembers that Mrs. Who had given her the spectacles, and she figures that this must be the last chance to use them and get to her father. She puts them on and is able to fling herself through the transparent glass and into the imprisoning column that holds her father. The inside of the column is dark and it is only because of the spectacles that Meg can see.