Optical insert for eyewear

There is provided an optical insert for transforming conventional eyewear into eyewear having an additional purpose. The optical insert comprises an extender portion which holds a lens on a first end and a mounting assembly on a second end opposite the first end. The mounting assembly comprises a profile which matches the profile of the conventional eyewear lens retainer. The lens of the conventional eyewear is configured to be removed and replaced with the optical insert. In one embodiment, the lens of the optical insert can comprise dark lenses which can be useful, for example, to transform conventional eyeglasses into prescription sunglasses.