I have 2.5D astigmatism in my right eye, yet i passed the Class 1 medical in March. I guess I just got lucky, however it did take a lot of letter correspondance between the CAA and I. Originally, they wouldn't let me take the medical because I submitted a prescription which was outside of the initial limit (2.00) and it was after December 2006 so the 'deviation route' was closed. Following this initial denial, I saw many different opticians, and had eyetest after eyetest, until one (a highstreet chain that shall remain nameless) reported that i had only 1.75D in that eye! I then sent this report off to gatwick, and said that the original optician had got it wrong. It seemed i created enough doubt about my eyesight to require their optician to solve it once and for all.
My class 1 exam was an extremely nerve-racking event. I had to wait for about an hour in the waiting room as i was having an 'eyesight first' exam- they do this for marginal candidates to save the expense of the rest of the medical should they fail. After the very thorough test, the optician and I sat down in a side-room, i was convinced i'd failed, he said 'I measured your Astigmatism, it was much closer to your original prescription, 2.5 Dioptres'...Oh noooo i thought...that's it... the dream's over, but he continued to say..'im passing you fit class one'
I have no idea why he decided to pass me, maybe because i was such a pain writing to him all the time! or he was just in a good mood that day
Moral of the story...don't give up, do whatever it takes to pass. The CAA are your friend and they do want you to pass.