We may find marks on the progressive glasses purchased, and some even think that are the defects of the lenses. Theses marks appears as circles, letters, and numbers as shown in the picture below.
Segment Height, also known as Seg Height or SH, is the vertical measurement in millimeters from the bottom of the lens in your frames, to the beginning of the progressive addition on a progressive lens. Segment height does not apply to Single Vision lenses. The determined Segment Height is specific to each frame and wearer.
Here are some tips on how to find the best-fit frames on our web site.
Development of round glasses History of round glasses One of the earliest etchings of eyeglasses, dating back to the 13th century, shows some studious clergyman in some ancient monastery squinting at his parchment from behind a pair of round-framed specs. Later, in the early 1600s, a portrait of that well-known cardinal, Fernando Niño de Guevara, shows him sporting yet another pair of circular frames. Of course, these early varieties wouldn’t exactly fly off the shelves today. They often lacked temples, needed to be held by a hand, and were either made of leather or weighty metals like lead and iron. It could be said that the glasses of yesteryear weren’t the best lookers, but they didn’t need to be. They were purely functional, the reserve of a studious and god-fearing elite.
I have an eye prescription on the paper, How to upload the prescription on leoptique