Isom--
In addition to being in agreement w/Dr. Doan above, I think one way you can proverbially kill two birds w/one stone is to do research in oculoplastics as a med student...that way you can explore your interest in both ophtho and plastics. Also, if you do go into ophtho and decide on plastics, you have a fair amount of research and experience under your belt to show your long-standing interest in that particular fellowship.
That is what I did as a med student...though it ended up teaching me ophtho is cool, but that oculoplastics isn't really for me 🙂