Which of the following would be the best material for an intraocular lens? IOLs are inserted into the eye to replace a damaged or poorly functioning lens to treat myopia and cataracts. They must be flexible enough to change shape slightly when pulled by the ciliary muscles of the eye.

The following multiple$-$choice options contain math elements, so you may need to read them in your screen reader's $$reading$$ or $$browse$$ mode instead of $$forms$$ or $$focus$$ mode.

Choice $1$ of $8$:Single$-$crystal metal with no impurities

Choice $2$ of $8$:Polycrystalline metal alloy, small grain size, dislocations

Choice $3$ of $8$:Semiconductor with Eg$=1\mathrm{.}0$ eV

Choice $4$ of $8$:Semiconductor with Eg$=4\mathrm{.}9$ eV

Choice $5$ of $8$:Ceramic insulator, amorphous

Choice $6$ of $8$:Ceramic insulator, crystalline

Choice $7$ of $8$:Silicone

Choice $8$ of $8$:None of the above