(Disclaimer- this article is not legal advice, seek counsel from your accountant or lawyer for your particular situation)
Deciding which way to get paid for the work you do is a very circumstantial decision.
It depends on the job criteria you have set up with the practice you will be working for.
Will you be working there long term? Will you be bringing your equipment or using theirs?
Its also important to talk with your accountant to help you figure out which scenario works best for your situation to be most beneficial tax wise and that you are doing things legally correct. No one likes to be surprised at the end of the year with a huge bill owed to the government.
If you are moonlighting, it’s always a good idea to set up an LLC to run all the professional fee through and to have individual optometric malpractice insurance (which you can get a good rate through the AOA).
The LLC provides a protective barrier between your personal and professional assets in the event there are any legal issues. Plus, there are tax advantages to doing this as well such as writing off business expenses.