Hmmm. Why would you want to make things harder on yourself or set yourself up for disappointment? While D.O.s do match into ACGME programs, that is the exception. It is the exception not because D.O.s are no good or would not make excellent residents but because of a few issues.
1) In a high demand field like ophtho there are plenty of M.D.s that go unmatched so if there is a "tie" in applicant qualifications between an M.D. and a D.O. it would only be fair to accept the M.D. who the ACGME is obligated to train over the D.O. who they are not obligated to in any way. Other fields like IM have a surplus of openings so there is no issue with an ACGME program accepting a well qualified D.O.
2) Research seems to be important for applicants to ACGME programs and most (not all) Osteopathic med schools don't make it easy to do research. Most schools do not have an ophthalmology department. This means you will have to look harder and work harder to find research to become involved in.
3) The Big Wigs of Ophtho are not generally found in the academic depts of Osteopathic med schools. Since LOR from Big Wigs tend to help an application, you would have to again work harder to become exposed to the Big Wigs and to obtain rotations through their depts.
4) USMLE ignorance. Unfortunately some folks think COMLEX will be enough for the application, but one must really take the USMLE because it is really all the allo programs understand. I found that the USMLE stressed some topics that COMLEX didn't even cover so you would have to be sure to study a little differently for each test. BTW, it sucks to take 2 tests, esp since COMLEX is still the 2 day, 8 hr per day, pencil and paper marathon. Just take one set of boards if you can, save time and money!
5) Lack of support from Osteopathic med schools. Want to apply for a subspecialty? In general one is hard pressed to find a suitable mentor to help with the application process. When I thought I wanted to be a pathologist I had plenty of help since my school had a good path dept. Once I decided to apply for ophtho I was on my own and had to figure things out by trial and error and many a phone call and email to folks in Michigan.
That is about it. I love my profession and really appreciate the approach to patient care that I developed in my training. Even now as a resident, I am always mindful of Osteopathic Principles when I care for patients (structure affects function, look at the patient as a whole, etc...) BUT, when I applied to school I thought I wanted to be an FP. Since I was able to get an AOA residency spot I was thankful that despite deciding on ophtho in my MS4 year I was able to pursue ophtho without losing any time. If I was in allopathic med school and decided on ophtho in my MS4 year, I would have been SOL! If I had known from the start that I wanted to be a pathologist or ophthalmologist, I would have gone the allopathic route because there is more opportunity. If you have strong family reasons for choosing D.O. or other very compelling reasons, go for it, just know that it will be more work and you may likely have to try for an AOA residency anyways and you may still not match. (One D.O. I know knew he wanted ophtho from the start so that is all he concentrated on to the neglect of other work and his boards and he ended up not matching despite impressive research and LOR from allopathic Big Wigs.)
As far as opportunity for fellowships and practice after residency, you can do whatever you want. You will be limited by your own ability not your degree. You aren't tripping over D.O. ophthalmologists because there aren't that many and those that there are seem to be concentrated in MI, PA, OH, FL, and CA.
HTH and good luck on your decision.
