Year Invented - late 13th century (estimated 1286)
Inventor - Italian Monks
Function - Provides one consistent optical power across the entire lens to correct a single type of vision problem.
Details - Considered the first form of wearable eye glasses, and are most commonly prescribed for nearsightedness (myopia) and farsightedness (hyperopia).
Single-vision lenses address only one vision problem across the entire lens.
Photo Credits: Zeiss