There are quite a few things wrong with this factoid. Number one, James Ayscough was not a "designer", he was a scientist. Per Wikipedia, he "began experimenting with tinted lenses in spectacles in the mid-18th century. These were not "sunglasses" as such; Ayscough believed blue- or green-tinted glass could correct for specific vision impairments. Protection from the sun's rays was not a concern of his."

In addition, ancient Chinese and Eskimoan civilizations have been found to have used either smoked quartz or ivory with slits (respectively) to shield their eyes from the sun. These could be known as the first pairs of "sunglasses".