Perhaps theres been some changes, but when I initially applied for the CF, it was for the combat arms, and because of my eyesight I was told that they couldnt accept me for one of those trades. I was rated at V4. (I believe that my eyesight was approximatly -2.25 or so at the time.) If I remember correctly, they said that they would accept V3.
Seeing as its just an astigmatism, as the others have said its not a problem.