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    Re: Polarising Filters
    From: Ken Muldrew
    Date: 2007 Nov 26, 14:19 -0700

    On 26 Nov 2007 at 14:09, Michael Daly wrote:
    
    > Ken Muldrew wrote:
    >
    > > I have attached a short article from Ophthalmic Physiology & Optics from
    > > 2001 in which damage from the sun is discussed.
    >
    > They dismiss UV as a factor in damage - please note that this is in
    > reference to _retinal_ damage.  UV exposure of the cornea remains a
    > risk; it will tend to accelerate the rate at which the cornea yellows and
    > can cause burns to the corneal tissue as well (just as UV causes skin to
    > sunburn).
    
    Sure, but that happens any time your eyes are exposed to the sun (whether
    you are looking at it or not). The article was discussing damage that
    resulted from the focussing of sunlight through the lens of the eye.
    
    > I find this article at odds with some of the research results of a
    > former colleague (Chou) who had a specific interest in eclipses.  Its
    > dismissive tone tends to make me want to take its conclusions with a grain
    > of salt.  Chou's advice is somewhat more conservative and is
    > experience-based (has has observed two saros cycles worth of eclipses, with
    > several in the same series); he is an eye-care professional, professor and
    > researcher at a local university.
    
    I'm all for being conservative when looking at the sun (I've had
    snowblindness before and I can attest to the extreme discomfort). The
    advice given in this article is that anything that attenuates the sun's
    light enough to comfortably look directly at the sun is sufficient to
    avoid retinal damage. Can you tell us what your former colleague's advice
    was?
    
    Ken Muldrew.
    
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