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Effects of sunglasses & photochromic lenses on dark adaptation

  • 1.  Effects of sunglasses & photochromic lenses on dark adaptation

    Posted 2 hours ago
    Fellow Perception and Performance Technical Group Members,

    I am writing to ask for your thoughts and / or suggested reading / references on the following.

    The scenario:
    • An older person is wearing prescription lenses with photochromic lenses (sometimes referred to as "Transitions Lenses," though I'm not sure they were this specific brand).
    • The person is outside in bright sunlight long enough for the lenses to darken. 
    • The person then walks into a portico area that is shaded from direct sunlight but that is still relatively bright due to reflected sunlight from windows and open doorways as well as significant artificial overhead lighting. 
    My questions:
    • How would we expect the photochromic lenses to affect the wearer's dark adaptation when walking from the direct sunlight into the shaded area? Note that we are not talking about dark adaptation to the level of scotopic vision since it is still relatively bright.
    • Presumably the darkened lenses prevent some of the pigment bleaching that would occur in the viewer's cones if no filters were worn in the bright sunlight. How does this impact the person's ability to see when walking into the less bright area?
    • Is there data that would be relevant to this situation that could describe the time-course of adaptation of the entire system (human visual adaptation + the lens transmission change) in such circumstances?
    I've begun a lit search but not coming up with much so far. I would appreciate any guidance that you can provide. Feel free to post to the group and / or contact me directly at my work email address <Keith@HumanFactorsInContext.com>.

    Keith 

    Keith S. Karn, PhD
    Principal
    Human Factors in Context LLC
       Mobile: 215-531-1521


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