Workplace Illumination - Part 9: Light-Related Maladies

     Like all human capabilities, visual performance is influenced by a number of factors.  Inborn imperfections in the eyes, physical injury, infection, and other ailments can affect visual capabilities.  Changes in visual capabilities are also experienced due to advancing age.  The variety of potential afflictions results in a wide range of severity and compensability.
     Focusing an image on the retina, differentiating colors, and distinguishing between objects or details are functions of the visual system that can be effected by various maladies.  Changes can also occur in the non-visual system, affecting circadian timing and related functions.  These changes may be more difficult to correlate with perceived effects, as links to non-visual system functions are typically less obvious than that of, say, a blurred image to visual system functions.
     An introduction to several light-related maladies, including innate and acquired conditions, is provided in this installment.  Effects on workplace visual performance, potential treatments, and countervailing techniques are presented in brief.  The prevalence and severity of these conditions among the workforce are parameters that must be considered in an analysis of lighting system design requirements.

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