Beats 45 applicants for three spots, in the day.
You will not be competitive unless you have a GMO tour. Straight-through training is rare.
The reason there are three spots and not the eleven that there used to be (Oak Knoll closed, nix 3, Bethesda closed, nix four, Balboa went down to 3 from 4, the sad history there) is that since ophthalmology procedures have been radically trimmed in CMS Medicare payments, the incentive for many military doctors to leave the military as soon as possible has gone away; that and the fact that most retirees are sent out to the community through TRICARE and not seen in the .mil anymore. So ophthalmology billet vacancies are fewer and, unfortunately, so are the incentives to select residency graduates for fellowships.
I think there is little chance for residency deferment. The only case I know of is a guy from my med school who asked for a deferment for anesthesia during the military match, got the deferment, applied for civilian ophthalmology knowing the early ophtho match would be over and done before the Spring main match for civilian anesthesia, got a spot in ophthalmology in a Big Southern State, and went back to the Navy told them he had "changed his mind" and asked if he could still have his deferment, but for ophthalmology instead. And they let him. He cleverly must have known that by then the Navy's internship billets were already filled up (and also the GMO replacement slots, which really is what drives the internship numbers) and that they really didn't need him right away. So if I were to suggest a means by which you might get a deferment, that would be it, because it is the only way I have seen it work.
Count on the GMO tour. You can apply without one, but there will be very well qualified people applying with one.