I'm not sure about the smoking bit, but as far as the eye test goes they do conduct a very thorough one at the initial Class I medical. Details of limitations on eyesight can be found on the CAA website; you will also need to take your current prescription with you to the medical as far as I can remember.
I don't wear glasses but I had an eye test at my local opticians before my initial Class I last year and took with me the information off the CAA website; when discussing the results, I showed the optician the CAA info and she said "yeah, you're within them, no problem". Then, when I went for the Class I, the optician told me that I was right on the borderline of needing/not needing glasses. The test with him was a lot more thorough.