Try a search for 'orthokeratology' on Wikipedia and Google. The wikipedia article gives a good background on what the treatment is.
I can't argue for or against it as I only had a consultation, but I gathered that Ortho-K is only good for correcting vision that is within the CAA limits, thereby making it no good for obtaining a class 1. My consultation was in May 2006, so there might have been some change since then...
waterpau