Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Corrective lens:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

Lens manufacturers claim that aspheric lenses improve vision over traditional spheric lenses. This statement could be misleading to individuals who do not know that the lenses are being implicitly compared to "a spheric flattened away from best-form for cosmetic reasons".[citation needed] This qualification is necessary since best-form spherics are always better than aspherics for an ophthalmic lens application.[1] Aspherics are only[citation needed] used for corrective lenses when, in order to achieve a flatter lens for cosmetic reasons, the lens design deviates from the best-form sphere; this results in degradation of the visual correction, degradation which can, in some part, be compensated for by an aspheric design. The same is true for atoric and bi-aspheric.