I am potentially switching to the Army for aviation. What advice can people give me for switching services/branching Aviation?

Take a look at AR 40-501, particularly chapter 6. Para 6-14 might somewhat answer your question, but it is an ambiguous answer. Most waivers are made on a case-by-case basis making it impossible to say if your vision deficiency would be waiverable or not. If you want to see how the process works, para 6-18 talks about the aeromedical waiver process. I had a flight surgeon tell me once that that his job was to keep people out of aviation when they first apply and keep them in once they were accepted; meaning it is harder to get a waiver approved as a non-aviator. If you are already a pilot and develop a condition your chances of waiver approval increase. I have personally never needed a waiver so I don't have any firsthand experience; maybe some flight surgeons can weigh in on their experiences getting waivers approved.