N.C. Gen. Stat. § 90-255: Rebates.

It shall be unlawful for any person, firm or corporation to offer or give any gift or premium or discount, directly or indirectly, or in any form or manner participate in the division, assignment, rebate or refund of fees or parts thereof with any ophthalmologist, optometrist, or wholesaler, for the purpose of diverting or influencing the freedom of choice of the consumer in the selection of an ophthalmic dispenser. (1951, c. 1089, s. 23; 1981, c. 600, s. 20.)