I assume you are off the street in regards to OCS (not a prior or program person).
If you fail the flight physical in the first week you sometimes get "retested" on some items.
OC 1: A guy passes out giving blood during his physical. Passing out NPQ's you. He the chose to not redesignate (pick a new job), got sent to student pool and was eventually separated (6-7 weeks).
OC 2: A guy failed to meet eye standards for pilot. He was retested twice and failed all times. His dream was to be a pilot so he left to get PRK and was going to try to come back. Went to student pool and eventually separated (3 weeks).
OC 3: A guy failed to meet eye standards for pilot. He was retested and failed. His dream was to be a naval officer so he redesignated as a NFO. There was no break in training and he commissioned.
If you do not pass the flight physical for your designator, you can choose to leave with no penalty. If you DOR you can leave with no penalty.
When I say penalty, I do not mean to degrade the enlisted ranks. My thought process is that there will be no further obligation. In a medical case the option is truly yours to stay or leave. Keep in mind that even if you want to redesignate sometimes the community will not take you and you are out of luck.
The contractual obligation to enlist is for people who get money from the Navy. I was BDCP and got paid for 1.5 years prior to OCS. If I DOR'ed or got attrited (kicked out) I would be required to enlist as a striker for 2 years. If I got NPQ'ed I could try to redesignate or leave. The same goes for NUPOC (nuke bobble head guys) and CEC (civil engineers). If you are a prior then you fall back to your prior contract.
Now that those possibilities were explained, let's move onto depth perception. I failed the depth perception test at MEPS, went to a civilian doctor, passed their test and got in. I later took the same test once in OCS and once while checking in to API. I passed both times. What happened? I don't really know. The circles just didn't stand out the first time, but did the other times.
Here is what I did when I traveled to OCS. I got two copies of the letter my civilian doctor wrote to the Navy stating I had unremarkable depth perception (normal). One letter came with me when I checked in and one stayed in my car. If I failed the depth perception test for my flight physical I had a plan. I would present the letter to the doctor (assuming they lost the first one in my medical record) to explain the issue. Depth perception is something you generally have or do not have. It will not suddenly go away. Make sure to be professional and respectful to the doctor in this process. From here you would attempt to find a solution.
This plan was told to me by a former flight surgeon. At the end of the explanation he told me a great piece of advice, "Do not worry about going to medical. If everything goes right, it goes right. If it does not, then it does not. Try you best at everything and what happens happens."
Good luck with OCS and make sure you drink a shit ton of water the days before and the day of the physical. It takes a while to properly hydrate your so plan ahead.