Spectacles or Eyeglasses had no standard for a long time in their history. In 1833 William Beecher of Southbridge, MA. had a small jewelry and watch making business. He also felt the New England ingenuity could produce a better product. What he and four others made were standard spectacles with different lenses and the customer would pick a pair that best improved his or her eye sight.
This type of eyeglasses were the only kind until much later in the century.
Another tidbit is that sunglasses (tinted lenses) were out in 1880. Prior to 1875 the tinted lenses were used for medical purposes.