I've just got the telephone with aviation house,
The lady did state there is a 'deviation' rule applying for people with astigmatism's and other problems.
I have to get my optician and file a report which is my last ditch effort (pardon the pun!).
Thanks for all your help - if anyone can shed any light on the FAA's rules, that'll help me plan route 'B'!
Regards
Dan