Maybe the greenish-white polish contained a chemical that, upon contact with glass, produced an optical distortion.

NEWYORKER: Miracle Polish

That measurement uses another sort of optical distortion this time of the wavelength of light.

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Offering exceptional optical performance to provide minimal distortion and chromatic aberrations while suppressing ghosting and flare, the advanced lens unit allows for higher shutter speed and captures stunningly clear images.

ENGADGET: Panasonic's Lumix line gets a lot more crowded