The use of restricted spectral range red lenses for the diagnosis and relief of dazzlement of a rod monochromat

An infant rod monochromat was diagnosed and was then treated with the Younger PLS 550 lens. The comparison in use of PLS 550 and a neutral density lens confirmed the presence of cone dysfunction. The use of this lens takes advantage of the spectral shift in luminosity between rods and cones. Younger PLS 550 and PLS 530 tints are used for the relief of photophobia according to prevailing brightness. This paper discusses patient management with the use of these lenses and some characteristics of the vision of a rod monochromat.