Color in Sunglass Lenses∗

The extensive literature dealing with color in sunglasses is reviewed. With the exception of therapy in some uncommon illnesses, there is generally no advantage to vision gained by observing through colored, as opposed to neutrally‐tinted, lenses. On the other hand, some types of colored lenses have previously been shown to introduce considerable potential hazards in road traffic where traffic signal lights are used. It is concluded that all sunglasses, tinted contact lenses, and motor vehicle windshields should comply with the coloration limits previously proposed. viz., that the “signal visibility factor” (ratio of red to white light transmission) should be between 0.8 and 1.2. and that the excitation purity should not exceed 20%.