Mass. Gen. Laws ch. 176F § 7
Every registered optometrist shall have the right, on complying with such rules and regulations as the corporation may make, to enter into a written agreement with an optometric service corporation, doing business in the city or town where the said optometrist resides or has his usual place of practice, to perform optometric service. This chapter shall not change the normal relations between optometrist and patient, except as to the manner of payment and amount of fees which are to be paid by the optometric service corporation to participating optometrists on behalf of the subscriber. No officer, agent or employee of an optometric service corporation shall influence or attempt to influence a subscriber or a covered dependent in his choice of a participating optometrist. A subscriber or a covered dependent, subject to the by-laws, rules and regulations of an optometric service corporation and the terms and provisions of his subscription certificate, shall be entitled to the benefits of this chapter upon receiving optometric service from any participating optometrist or, in the discretion of the corporation, upon receiving optometric service from any non-participating optometrist in an emergency or when outside the commonwealth. A corporation may terminate its agreement with any participating optometrist at any time (a) for failure to comply with the reasonable rules and regulations of such corporation, including without limitation such rules and regulations as may be adopted governing the keeping of accounts, records and statistics, the making of reports and proof of services rendered, or (b) for presenting any fraudulent, unreasonable, or improper claim for payment or compensation.
Mass. Gen. Laws ch. 176F, § 7