Ultraviolet-Blocking Lenses Protect, Enhance Vision
- Friday, 01 January 2010
In the 1980s, Jet Propulsion Laboratory (JPL) scientists James Stephens and Charles Miller were studying the harmful properties of light in space, as well as that of artificial radiation produced during laser and welding work. The intense light emitted during welding can harm unprotected eyes, leading to a condition called arc eye, in which ultraviolet light causes inflammation of the cornea and long-term retinal damage.
To combat this danger, the JPL scientists developed a welding curtain capable of absorbing, filtering, and scattering the dangerous light. The curtain employed a light-filtering/vision-enhancing system based on dyes and tiny particles of zinc oxide—unique methods they discovered by studying birds of prey. The birds require near-perfect vision for hunting and survival, often needing to spot prey from great distances. The birds’ eyes produce tiny droplets of oil that filter out harmful radiation and permit only certain visible wavelengths of light through, protecting the eye while enhancing eyesight. The researchers replicated this oil droplet process in creating the protective welding curtain.
The welding curtain was commercialized, and then the scientists focused attention on another area where blocking ultraviolet light would be beneficial to the eyes: sunglasses. In 2010, the groundbreaking eyewear technology was inducted into the Space Foundation’s Space Technology Hall of Fame, which honors a select few products each year that have stemmed from space research and improved our lives here on Earth.
SunTiger Inc.—now Eagle Eyes Optics, of Calabasas, California—was formed to market a full line of sunglasses based on the licensed NASA technology that promises 100-percent elimination of harmful wavelengths and enhanced visual clarity. Today, Eagle Eyes sunglasses are worn by millions of people around the world who enjoy the protective and vision-enhancing benefits.
Maximum eye protection from the Sun’s harmful ultraviolet rays is critical to our ability to see clearly. This is because when light enters the eye, a series of events happen which can help, hinder, or even destroy our eyesight. First, light passes through the cornea and ultimately reaches the retina which contains two types of cells—rods (which handle vision in low light) and cones (which handle color vision and detail). The retina contains 100 million rods and 7 million cones. The outer segment of a rod or a cone contains the photosensitive chemical, rhodopsin, also called “visual purple.” Rhodopsin is the chemical that allows night vision, and is extremely sensitive to light. When exposed to a full spectrum of light, rhodopsin immediately bleaches out, and takes about 30 minutes to fully regenerate, with most of the adaption occurring in the dark within 5 to 10 minutes. Rhodopsin is less sensitive to the longer red wavelengths of light and therefore depleted more slowly (which is why many people use red light to help preserve night vision). When our eyes are exposed to the harmful, ultraviolet light rays of the Sun (UVA, UVB, and blue-light rays), damage to our eyes and their complex vision-enhancing processes can occur and not even be noticed until years later, long after exposure.