A surface-reduced photochromic glass containing silver halide crystals, having an original transmittance of 60-75%, a darkened transmittance of less than 30% at 25.degree. C., a faded transmittance equal to the darkened transmittance plus at least 25% and a value of at least 50%, a position in a color mixture diagram between 575 and 585 nm, the glass composition having a Na.sub.2 O content of at least 1% in its surface, or containing as additives 1-6 ppm Pd, or a combination of 2-10 ppm Au and up to 0.9% Er.sub.2 O.sub.3. The glass may be chemically strengthened and generally has a longer dominant wavelength when so treated.
An ophthalmic, protective, filter lens, and a method of producing such lens, the lens having a ratio of Z and Y tristimulus values between 0.25-0.40, a dominant wavelength between 570-580 nm. on a color mixture diagram, a sharp transmission drop between 450-500 nm. and a transmission not over 30% between 400-450 nm.
An ophthalmic, protective, filter lens, and a method of producing such lens, the lens having a ratio of Z and Y tristimulus values between 0.25-0.40, a dominant wavelength between 570-580 nm. on a color mixture diagram, a sharp transmission drop between 450-500 nm. and a transmission not over 30% between 400-450 nm. The lens is produced by firing a silver halide-containing, photochromic glass lens in a hydrogen-containing atmosphere within a temperature range of 465.degree. C. to 495.degree. C. for less than 20 minutes.
