Figure 9.

Two extreme cases that need to be considered: UV transmission (left, yellow) when the sun is in front of the wearer, and UV back reflection (right, purple) when the sun is coming from the back of the wearer.

Notes: Relevance of transmission and reflection properties depends on the solid angle of incident UVR. Incident angle, 0°, UVR (violet) is blocked efficiently by lenses. Reflection does not play a role. Incident angle, 135°–150°, with many antireflective coatings, UVR is reflected by the reverse side of the lens and refracted into the eye. This situation arises when facing away from the sun (sun almost behind the wearer).

Abbreviations: UVR, ultraviolet radiation; UV, ultraviolet.