6-Ethoxy-2-(6-ethoxy-3-oxobenzo[b]thien-2(3H)-ylidene) benzo[b]thiophen-3 (2H)-one.
21 C.F.R. § 73.3123
in effectEffective: 2024-07-01(a) Identity. The color additive is 6-ethoxy-2-(6-ethoxy-3-oxobenzo [b]thien-2(3H)-ylidene)benzo[b]thiophen-3(2H)-one (CAS Reg. No. 3263-31-8), Colour Index No. 73335.
(b) Uses and restrictions. (1) The substance listed in paragraph (a) of this section may be used as a color additive in contact lenses in amounts not to exceed the minimum reasonably required to accomplish the intended coloring effect.
(2) Authorization for this use shall not be construed as waiving any of the requirements of sections 510(k), 515, and 520(g) of the Federal Food, Drug, and Cosmetic Act with respect to the contact lens in which the color additive is used.
(c) Labeling. The label of the color additive shall conform to the requirements of § 70.25 of this chapter.
(d) Exemption from certification. Certification of this color additive is not necessary for the protection of the public health, and therefore the color additive is exempt from the certification requirements of section 721(c) of the act.
Source: eCFRURL: https://www.ecfr.gov/api/versioner/v1/full/2024-07-01/title-21.xmlFetched: 7/26/2026