THE HEAT IS ON
Did you know the idea to protect one’s eyes from the harmful effects of HEV blue light-while a hot topic these days-actually dates to the early 1900s? Prominent English scientist Sir William Crookes was asked to formulate glass that would provide protection from the new electric light. He was also tasked with protection against cataracts in the eyes of glass smelters resulting from infrared (heat) rays. Crookes tested over 300 combinations of metallic oxides added to clear glass to find one that would block infrared heat and ultra-violet rays while only minimally interfering with the visible portion of the spectrum, resulting in a pale blue gray Crookes glass (see ad, top right).
American Optical bought the rights to the glass in 1913 and promoted it as protection from UV. By adding ferric and ferrous oxides, a new glass called Cruxite was patented by AO and advertised in the ’20s. It had a pink hue available in varying shades of darkness, and was advertised to block UV and glare (top left).
The Soft Light lens was also introduced during this time, but rather than absorbing UV, it was formulated with manganese so the lens would maintain its cosmetically appealing pink hue. It was manufactured in the first U.S. glass plants of Bausch + Lomb and enjoyed a long run of popularity as a comfort lens that reduced glare.
Courtesy of Optical Heritage Museum (opticalheritagemuseum.org)