Early lens use: lenses found in context with their original objects.
The early history of optical lenses is poorly defined. Lens-like objects were used for jewelry or decorations for thousands of years, and technology necessary to make lenses was available. In antiquity, a number of activities would have benefited from image size enhancement, and a few lens-like objects have been found at sites where lens use was logical. Means for enhancing visibility of objects have been suggested. Two alternative positions are considered in modern literature: (1) Lenses existed and (2) Fine close work was executed by relatively young and/or nearsighted individuals. Neither argument meets necessary and sufficient conditions for proof of the existence of or lack of lens use. Both forms of image size enhancement might have co-existed, and added factors such as ambient illumination, contrast between the object examined and its background, and shadows must have affected visibility of items viewed. Most probably, optical properties of lens-like elements were appreciated often, across time, by artisans. What is not clear is to what extent general use of lenses resulted. Here, I draw attention to a number of individual lens-like artifacts and the objects intended to be viewed through them. All were decorative pieces or articles of jewelry. The existence of such artifacts has been reported previously. The unique feature in each case presented here is that the lens-like element and object to be viewed were permanently linked together, i.e., "frozen" in time and space. It can be inferred that at least the artisan appreciated the resulting optical effects. Clearly, too, the artist/artisan had to intend the object to be viewed through the lens. This analysis provides an additional useful approach to assessment of early lens use.
Enoch
J M
JM
School of Optometry, University of California at Berkeley, USA.
D005139:Eyeglasses / Q000266:history*; D049690:History, Ancient; D049691:History, Medieval; D006801:Humans; D007909:Lenses / Q000266:history*; D012030:Refractive Errors / Q000503:physiopathology / Q000628:therapy; D014792:Visual Acuity