Yes. In practice, the O-1A is a work visa, so you must show that you are entering the United States to perform work.This is typically done through a U.S. employer. Alternatively, you may apply through an agent if your work is freelance or consultative in nature. In that case, the agent agreement and underlying contracts must clearly reflect the scope, duration, and nature of the work, and they should be appropriate for your background and level of expertise.