It is fairly routine now for USNA Mids who need it to have PRK surgery after signing their service commitment papers ("2 for 7's") at the start of their third year. However, there can be vision issues that prevent PRK. Also, other things can disqualify someone from pilot qualification: physical dimensions (too tall, too short, arm length out of proportion, etc) or performance on the required aptitude tests are just two reasons someone may not qualify.
As far as thinking ahead about career service options goes, while it's good to think about, your son's opinions could change radically between now and his SA graduation year. My Mid went into USNA thinking about a career as a SWO (surface ship officer), and she was absolutely delighted that women were not allowed aboard subs, as she had ZERO interest in sub service. Now, several summer trainings later, SWO is her very LAST choice of service, and subs (while not first choice) would be a totally acceptable alternative. My suggestion would be for your son to consider the aggregate of all the service possibilities in each case (LITS and others here can be of great help with CG options!). It may help him to think about the question, "How would I feel/react if I were assigned to service choice #3?" with respect to either service.
In the short term, it's important for your son to feel that he's a good "fit" with either USCGA or USNA, and for that decision, he needs to know as much as he can about each one. Not attending NASS is not a big deal wrt to USNA; most of my Mids' friends did not attend NASS. I would suggest that, even though he participated in AIM, that he should, if possible, attend a Candidate Visit Weekend (CVW, or whatever it's called at USCGA) at both places. That will give him a much better feel for life as a Plebe/Swab during the academic year at each place.
Congratulations to you and your son. Choosing between USCGA and USNA is a win-win situation!
As far as thinking ahead about career service options goes, while it's good to think about, your son's opinions could change radically between now and his SA graduation year. My Mid went into USNA thinking about a career as a SWO (surface ship officer), and she was absolutely delighted that women were not allowed aboard subs, as she had ZERO interest in sub service. Now, several summer trainings later, SWO is her very LAST choice of service, and subs (while not first choice) would be a totally acceptable alternative. My suggestion would be for your son to consider the aggregate of all the service possibilities in each case (LITS and others here can be of great help with CG options!). It may help him to think about the question, "How would I feel/react if I were assigned to service choice #3?" with respect to either service.
In the short term, it's important for your son to feel that he's a good "fit" with either USCGA or USNA, and for that decision, he needs to know as much as he can about each one. Not attending NASS is not a big deal wrt to USNA; most of my Mids' friends did not attend NASS. I would suggest that, even though he participated in AIM, that he should, if possible, attend a Candidate Visit Weekend (CVW, or whatever it's called at USCGA) at both places. That will give him a much better feel for life as a Plebe/Swab during the academic year at each place.
Congratulations to you and your son. Choosing between USCGA and USNA is a win-win situation!