Okla. Stat. tit. 85A, § 56

A. If the employer has previously contracted with a certified workplace medical plan, the employer shall select for the injured employee a treating physician or chiropractor from the physicians or chiropractors listed within the network of the certified workplace medical plan. The employee may apply for a change of physician or chiropractor by utilizing the dispute resolution process set out in the certified workplace medical plan on file with the State Department of Health. B. If the employer is not covered by a certified workplace medical plan, the employer shall select the treating physician or chiropractor. The Commission on application of the employee shall order one change of treating physician or chiropractor. Upon the Commission's granting of the application, the employer shall provide a list of three physicians, one of which may be a chiropractor, from whom the employee may select the replacement.