California Code, Business and Professions Code - BPC § 3042.5

(a) The practice of persons actually enrolled as undergraduate or graduate students of optometry in the clinical departments of schools or colleges of optometry accredited by the board shall be exempt from the provisions of this chapter;  provided, however, that such practice shall be entirely confined to the operations of the clinical department of the accredited school or college of optometry and shall be carried on only in pursuing the study of optometry.

(b) The board may grant, for specified periods, exemption from the provisions of this chapter to any person who is licensed in another state or country and who is employed as a clinician or instructor by an accredited school or college of optometry.  Such exemption from the provisions of this chapter shall extend only to practice which is conducted for educational purposes and which is confined to the clinical department of the accredited school or college employing the person to whom the exemption is granted.