Go with your heart, whether it is Cardiology or Ophthalmology. If ophtho is truly the way you want to go, then you have some work to do over the next few months. First, since your step 1 is below the average (235 last year), you should take step 2 as soon as possible in hopes of bringing it up. Your grades should be fine, and at this point there is nothing you can do about them. You didn't mention what medical school you are from (top 5, 10, 25, 50), but that plays into the whole equation also. Also, how strong is the ophtho department at your school? You should start getting involved with your home department ASAP, making contacts and doing research. You don't need to have something published by application time, but you want to dedicate some time, so that you can talk about the research during interviews. Depending when you start 4th year, take the one month home ophtho rotation first. Read, read, read before the rotation. Try to work with some of the big names at your program in hopes for a LOR. That brings us to the most important part of the ophtho application, the LOR. Ideally, you will want two ophtho letters from attendings that know you really well. You want them to at least remember your name if they get calls about you later. Finally, you might consider doing an away rotation at a program of interest, or a big name program. There are pros and cons to each, but we will leave that to another discussion. The target date for submitting your application is end of August - beginning of September. Shoot to have step 2 scores back before then, 2 ophtho letters in your hand by then. It may seem like a lot to do in a short time, but if you want it, you can do it. Good luck and please feel free to ask me other questions.