Field of vision EN 168 clause 18 Spherical, Astigmatic, and prismatic refractive powers EN 167 clause 3 Diffusion of the light EN 167 clause 4.2.2 Filter material and surface quality EN 167 clause.5 Extreme temp. Conditioning and test for increased Robustness EN 168 clause 3 Conditioning 55ºC during 60 min EN 168 clause 5 Resistance to high temperature EN 168 clause 5 50 h UV Conditioning, transmittance, and diffusion EN 168 clause 6 / EN 167 clause 4.2.2 Resistance to ignition EN 168 clause 7 Transmittance variation EN 167 clause 7 Protection against impacts high speed particles EN 168 clause 9.2.1 Protection against drops and liquid splashes EN 168 clause 12 Protection against large dust particles EN 168 clause 13 Protection against gases and fine dust particles EN 168 clause 14 Lateral protection EN 168 clause 19 Sand abrasion conditioning + light diffusion EN 168 clause 15 Visible and ultraviolet transmittance EN 170