Optical correctness: clear sight without distortion

If a pair of glasses distorts the field of vision, this results in headaches and tiredness.

Filtral sunglasses and reading glasses, regardless of the material from which the lenses are made, possess a high surface quality, which does not have streaks, specks or air bubbles. For sunglasses, optical correctness of quality category 1 is generally achieved according to these requirements. In the case of extremely curved lenses, quality category 2 is achieved for technical reasons.

This test proves it: if you hold the glasses approx. 20 - 30 cm in front of your eyes and focus on a straight line, perception is true to reality.