I don't think anyone on these forums would say I'm anything besides a HUGE supporter of DOs, etc, but if you're shooting for ACGME ROADS ... you're better off trying to do so from a MD school. However, remember that there are so many factors to discuss here that it's inane to even discuss this:
1. It's a pre-med choosing a school bc they want to enter a specific field at 20 years old. You will change your mind ...
2. There is absolutely no guarantee that you'll get Ophthalmology just because you're an MD. Remember that it's absurdly competitive (ROADS in general), and trying to moonwalk your way into a competitive ACGME residency with average grades, LORs, and USMLE SIMPLY because you went to a state MD school aint gonna happen. The 260+ people with 2 years of Ophthal research from one of the ivory tower med centers will smack you down.
3. I don't know how the DO Ophthalmology (is there a worse word to spell ??) world is like, but my guess it that it's small and networking/knowing the right people goes further than it would in the ACGME world. What I mean by this is that the qualifiers for who gets what may be different.
4. I don't think ACGME Ophthal is quite as guarded from DOs as fields like ENT, PRS, etc (like others were mentioning). I seem to see these on match lists on a decent basis and I used to talk with Dr. Saib on this site all the time - a DO from PCOM who is not an ACGME Ophthal resident.
Bottom line ... you chances are probably better coming from the MD ... especially if you specifically want ACGME residencies. However, like I pointed out, there are FAR to many variables to even really bother with this discussion, and AOA residencies/getting an Ophthal residency from the DO side is one of them/it doesn't seem "impossible" for DOs