it's not that hard to manipulate your app for different specialties, just do a bunch of different stuff in med school, you should be good at boxchecking by now
sign up for everything FM, IM, gen surg, and optho related in your school as far as student and interest groups
same for psych, path, rads, anesthesia, neuro depending what backups you want
do well on those rotations, good news is schools require a clerkships in 5 of 9 I listed
do underserved work of some sort as your EC, that will help if you have to go FM/IM/psych backup, and can't hurt your optho app
I don't know how best you put together 4th year for optho, you'll have to look into that
if it were me I would put a couple of backup specialties down that might help a scramble or another match
FM, IM, rheum, neuro, path at least are tangentially relevant and allow you to continue to cultivate backup specialty interest cred and aren't the worst rotations for 4th year
when you are on these "backup" rotations before 4th year, claim that you are split between them and maybe a specialty, you're not sure which (hopefully this is true? if you're optho or die and can't say anything else, keep it to yourself?),
treat your IM rotation very seriously, since you'll need to apply IM prelim anyway, and maybe you'll want IM cat as your backup and then specialize into something else with fellowship, but know that you're not supposed to plan to go from IM cat --> optho, (I wouldn't, you'll burn a bridge, the only thing worse than burning a bridge is doing so premeditatedly), you can go IM prelim --> IM cat sometimes
treat your surg rotation very seriously, I think one pathway is surg prelim --> optho but I thought surg prelims were more difficult than IM prelims to not only obtain but actually *do*
neuro --> neuro-optho can be one pathway that is similar work, but not at all surgical
neuro is less competitive than optho but I don't know if it's a good backup for you, and I don't know how competitive it is or easy it is to go the neuro-optho pathway, the person I have seen practice this way I think just sort of created their practice to be that way but I'm not sure
just my ideas on worst case scenario career planning for all students