Anti Reflective Coating
AR coatings reduce reflectance through the process of "optical interference" which counteracts reflected light waves. As a result, reflected light is reduced while light transmission is increased.
For CR-39 lenses, approximately 8% of transmitted light is lost to reflectance on the lens surfaces - 4% on the front surface, and 4% on the back surface. Only about 92% of light entering the lens is transmitted to the lens wearer's eyes. A high index material with a refractive index of 1.6 is transmitting only about 90% of incident light, with a 10% lost to reflectance. When coated on both front and back surfaces of a lens, an AR coating is designed to increase the percentage of transmitted light for both CR-39 and high index lenses to approximately 99%.
Scratch Protection Coating
Light weight hard resin lenses can be more easily scratched than glass lenses. Special coatings have been developed to help protect lenses from normal scratching. The modest additional cost for such scratch coating is a prudent investment.
UV Protection
The ultraviolet rays in sunlight pose potentially devastating harm to the eyes. Special treatment for hard resin lenses completely blocks hazardous UV light. Lenses like poly carbonate and high index include built-in UV protection.
