Every person who had been engaged in the practice of optometry in the State for two years prior to the date of the passage of this Article shall hereafter file an affidavit as proof thereof with the Board. The secretary shall keep a record of such persons who shall be exempt from the provisions of the preceding section [N.C. Gen. Stat. § 90-118]. Upon payment of three dollars ($3.00) he shall issue to each of them certificates of registration without the necessity of an examination. Failure on the part of a person so entitled within six months of the enactment of this Article to make written application to the Board for the certificate of registration accompanied by a written statement, signed by him and duly verified before an officer authorized to administer oaths within this State, fully setting forth the grounds upon which he claims such certificate, shall be deemed a waiver of his right to a certificate under the provisions of this section. A person who has thus waived his right may obtain a certificate thereafter by successfully passing examination and paying a fee as provided herein. (1909, c. 444, ss. 6, 7, 9; C.S., s. 6692.)