Most FMG's matching in ophthalmology usually have trained in ophthalmology in other countries and usually have practiced for many years. They usually do several years of research here in the U.S. and/or clinical fellowships in the U.S. before applying for ophthalmology.
I can't say this is the case for everyone, but this is what I have noticed from a few FMG's I have met currently in ophtho residency programs.