Cal. BPC § 3042

The provisions of this chapter do not prevent a licensed physician and surgeon from treating or fitting glasses to the human eye, or from doing any act within the practice of optometry, or a licensed physician and surgeon or optometrist from filling prescriptions or orders, nor do they prevent the replacing, duplicating or repairing of ophthalmic lenses, frames, or fittings by persons qualified to write or fill prescriptions or orders under the provisions of this chapter, nor prevent the doing of the mechanical work upon those lenses, frames, or fittings by an assistant, nor prevent an assistant acting under the responsibility and direction of a physician and surgeon or an optometrist from using any optical device in connection with ocular exercises, vision training, or orthoptics, or acts set forth in Section 2544.

It is unlawful for a person to dispense, replace, or duplicate an ophthalmic lens without a prescription or order from a licensed physician and surgeon or optometrist.