Protective filter lenses.

摘要

An ophthalmic protective filter lens having a scotopic transmittance lower than the photopic transmittance by more than a factor of two, a dominant wavelength within the ranges of 580-605 nm and a color purity of 75-85 whereby colors perceived through the lens are approximately those of the scene being viewed. A method of producing an ophthalmic protective filter lens which comprises firing a photochromic glass lens in a hydrogen-containing atmosphere within the temperature range of 400-430 DEG C for a time of 1-8 hours to impart a scotopic transmittance lower than the photopic transmittance by a factor of at least two, a dominant wavelength within the ranges of 580-605 nm and a color purity of 75-85 whereby colors perceived through the lens are approximately those of the scene.