PHOTOCHROMATIC SUNGLASSES

Photochromic lenses change from light to dark depending on the amount of ultraviolet light they are exposed to. Early photochromics were strictly glass lenses, but today, you can choose from regular plastic, polycarbonate and high-index glass and plastic.

Light Adjusting Lenses are a great example of a remarkably smart technology that enables you to see clearly and more comfortably in virtually any light condition.

The reason these lenses darken in sunlight but not indoors under artificial light, is that room light does not contain the UV (short wavelength light) found in sunlight.

Typically, photochromic lenses darken substantially in response to UV light in less than one minute, and then continue to darken very slightly over the next fifteen minutes. The lenses fade back to clear along a similar pattern. The lenses will begin to clear as soon as they are away from UV light, and will be noticeably lighter with in two minutes and mostly clear within five minutes

What are photochromic lenses?

A photochromic lens is the type of lens that changes its colour/tint depending on the amount of light (ultraviolet rays) that are cast upon the lens.  When more light is encountered, the lens becomes darker.  Conversely, when less light is shined then the lens becomes lighter in colour.

Photochromic lenses are lenses that darken on exposure to UV radiation.  Once the UV is removed (for example by walking indoors), the lenses will gradually return to their clear state.  Photochromic lenses may be made of either glass or plastic.  

How do photochromic sunglasses work?

The secret is in a material called Silver Halide.  It’s mixed evenly within each lens during manufacture.  The Silver Halide is the material that makes the lens change its colour based on ultraviolet ray exposure.

You might also be interested in learning about Polarised Sunglasses.