What is classified as a contact lens blank?

A contact lens blank refers to an unfinished lens that has not yet gone through the additional processes of grinding, polishing, or coating to become a functional contact lens for wear. The term "blank" emphasizes that it is a starting point in the manufacturing process, rather than a completed product ready for prescription use.

In this context, a button is a physical representation of a lens in its most basic form, often used in reference to the material of a lens before it undergoes shaping and finishing. It serves as a foundational piece that can eventually be customized into functional contact lenses to correct vision problems.

The other choices involve different components or aspects associated with contact lenses but do not directly relate to the concept of a blank. A lens prescription is specific to a patient's needs, a standardized fitting guide assists in selecting lenses rather than being a lens itself, and a lens care solution pertains to the maintenance of lenses post-manufacture. Therefore, the classification of a contact lens blank as a button correctly identifies it as a precursor in the lens production process.