HWD,
Funny you should say that because I have been going to bed rather late recently, mixture of working hard, playing hard and late night phone calls to the girlfriend!
I really hope this is right as Flyinf for Fun said that it is highly unlikely that my eyes could have deteriorated so quickly.
Not long till the end of uni term so will get some good rest soon!
Thank you both for your help, you have really put me at ease!