"Take a look at the outrageous health claims made by colorful charlatans of the 18th and 19th Centuries. Their bogus remedies claimed to cure poor eyesight and anything else that might trouble you."One of my favorites is The Blue Glass Deception, which was debunked in a Scientific American article (read part of the article here at Chest of Books.)
Here's a quick bit of the history of healthy blue glass from the Lynn Museum and Historical Society in Lynn, Massachusetts.
Ironically, blue light is used in modern-day medicine, in Photodynamic Therapy (also known as PDT or Blue Light Therapy.) Some research has shown that blue light, with its shorter wavelength, is more effective than regular white light at reducing seasonal affective disorder symptoms (SAD.) See this article from the Mayo Clinic>>