I would definitely email them to ask about this, but the way I interpreted that was to say that you had to have all your prereqs done by the summer before you were scheduled to enter, not necessarily that you couldn't take any prereqs in any summer. The line on the webpage I found says "Courses completed between the end of May and the beginning of September of the year you enter Optometry will not be considered by the Admissions Committee." For example, if you were applying to enter in September 2012, you would have to have all your prereqs done by May 2012 - you couldn't take your English course in summer 2012, but you could have taken it in summer 2011. I looked back at your previous posts and I see you're applying this summer for entry in September 2012, so it seems to me that you should be fine taking your English course this summer if you want! You just have to have all your prereqs done by next May.