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    Re: Correcting Night Vision
    From: Jared Sherman
    Date: 2005 Aug 11, 21:14 -0400
    Frank, I'm not sure that it is a "focus" issue per se. I have lasik damage, and during the day when my pupils are contracted I see better than I do at night. At night, glare, flare, and other distortion (like double vision and halos) become a problem because the cornea is now unevenly surfaced, and when the pupils are wide open at night--there is more lens area being used, so more distortions are in the "used" image path.
     
    Distortions in the cornea are actually common, and new procedures for corneal topography actually map the front and rear of the cornea separately to accomodate for them. Some of the ray tracing gizmos actually "project" a dot into your eye, and you use a joystick to mark a spot where you see it. That position is then compared to a mathematical position where a perfect eye SHOULD have seen the dot. And almost everyone has irregularities within the eye that show up during this kind of mapping.
     
    So with or without focus issues, your eyesight will be "degraded" when your pupils are wide open and more of the internal distortions affect the image you are seeing.
       
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