The fact that light can be both beneficial and harmful to our visual health has been longstanding & well documented.  Specifically, two types of light have been addressed by a variety of product offerings over the years:

· UV light damages the front-side of the eyes and is a major risk factor for many eye diseases, including cataract.

· Blue-Violet light, the portion of the visible light spectrum between 415nm—455nm, is harmful to retina cells and is a risk factor for the onset of age-related macular degeneration (AMD).

Blue-Violet light is unavoidable, and potentially harmful to overall eye health; however, the remaining portion of the Blue Light spectrum (known as Blue-Turquoise light [465nm—495nm]) plays an essential role in regulating the sleep/wake cycle, memory, cognitive performance, & other contributing factors to general wellness.

Crizal Prevencia No-Glare Lenses feature a selective filtering technology that was developed over four years of research & testing.  Using proprietary Light Scan™ technology, Crizal Prevencia lenses deflect harmful Blue-Violet light by 20%, while allowing beneficial Blue-Turquoise light to pass through.  Additionally, Crizal Prevencia lenses have an Eye-Sun Factor (E-SPF®) of 25, providing 25 times more protection from UV than no lens at all.  Finally, Crizal Prevencia lenses maintain excellent transparency, and feature complete protection against the enemies of clear vision: glare, scratches, smudge, dust, & water.

The residual color is blue instead of the usual Crizal green.  Cost is the same as Crizal Sapphire.

Click the following link for more details: 

http://www.crizalusa.com/Crizal-Lenses/Crizal-Prevencia/Pages/default.aspx