You had better have a good reason. Remember, everyone always thinks the grass is greener. About once a week most of the people in my residency will joke that they should have done radiology. You guys make a ton more money, and have better lifestyle from a vacation and teamwork standpoint. Also, you don't have to worry about marketing yourself to draw patients in or running a small business. Granted, your field has special stressors that I would not understand unless I did your residency, but I gaurantee that you are just trading one set of problems for another. I'm not saying this is the case, but If you truly hate radiology, don't just switch into ophthalmology because you think it is the easiest, highest paying best lifestyle subspecialty. I will also bet that most opth. residents have wanted to quit because they feel overwhelmed. Just take a deep breath and really ponder if you love helping people see. If you do, then there is no better field no matter what problems come with it. But, if it's just a job, there are better jobs to be found. Just my humble opinion. Best of luck in whatever you choose.
