Are anti-glare or anti-reflective lenses useful?

Discussion in 'Optometry Archives' started by midwest_46, Dec 21, 2006.

  1. midwest_46

    midwest_46 Guest

    Hello. I am a 33-year-old male.

    I need to get a pair of glasses with the prescription -5.00, -5.00 for
    driving, watching movies in a theater, etc. Would it be useful to buy
    lenses that have anti-glare or anti-reflective coating on them?

    What exactly does this coating do?


    Also, I may buy another pair of glasses to use as reading glasses.
    These glasses would be used for reading, computer use, etc. Would
    anti-glare or anti-reflective coating be useful for these glasses?


    I have had driving glasses and reading glasses before, and I don't
    think I've ever had anti-glare coating before. I'm not sure, but I
    don't think that not having this coating has been a problem.


    The coating can cost as much as an extra $75 for each pair of glasses.
    So, is the coating worth the price?

    Thanks for any information.


    John
     
    midwest_46, Dec 21, 2006
    #1
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  2. midwest_46

    Salmon Egg Guest

    Antiglare lenses have a polarized coating on them that ideally cuts out a
    bit more than half of the light. In addition, it cuts out some reflected
    light off of the pavement near what is the Brewster angle. Look that up in
    Wikipedia. I personally use CHEAP clip-on polarized glasses for that
    purpose.
    Antireflection coatings on glasses are nice but usually not durable. They
    are anti-FLARE as opposed to anti-GLARE. That is, the typically 4% of light
    at a lens air surface is reduced to about 1%. This lets more light get
    through and reduces the multiple reflections that might be annoying.

    I find antireflection coatings to be more useful in cameras where the stray
    light can leave a permanent reminder on the picture. For spectacles, you can
    often, but not always, move your head in a way to minimize the annoyance.
    -- Fermez le Bush
     
    Salmon Egg, Dec 21, 2006
    #2
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  3. midwest_46

    midwest_46 Guest

    So, let me see if I have this straight.

    Anti-glare coating keeps light out and decreases the brightness of,
    say, a computer monitor.
    Anti-glare coating can be purchased in cheap, clip-on form.

    Anti-reflection coating allows more light to come in. Thus, if I am
    wearing glasses with anti-reflection coating, my glasses reflect less
    light towards the people who are looking at me.
    So, if I am sitting at a computer, anti-reflection coating will make
    the monitor appear brighter than it already appears?


    Also, the lenses that I buy will be transition lenses. That is, when
    the sun goes up, the glasses become sunglasses. So, on a sunny day, is
    anti-glare coating necessary if I have transition lenses? And, as for
    anti-reflection coating, will transition lenses and the anti-reflection
    coating cancel each other out?


    Thanks.


    John
     
    midwest_46, Dec 21, 2006
    #3
  4. midwest_46

    Bucky Guest

    I'm no expert, but in my experience, those coatings are more for when
    other people look at your eyes, they don't see as much reflections off
    of them. And see less rings around the edges of the lenses.
     
    Bucky, Dec 21, 2006
    #4
  5. There you go again. Please don't use confusing terms like glare and
    flare. Glare refers to distracting light coming from around the object
    of regard, and cannot be corrected with any eyeglasses. Specular
    reflection refers to light that is reflected off a relatively smooth
    surface like a highway, water and computer monitor or eyeglass lenses.
    These the first two can be fixed with polarized lenses, the second by
    the use of anti-reflection coatings. Let's keep the terminology
    straight. In the present case, if he chooses high index lenses, which
    have significantly higher relflectivity, approaching 10%,
    anti-reflection coatings will definitely help. High quality ones (over
    $60) are quite durable and always come with guarantees.

    w.stacy, o.d.
     
    William Stacy, Dec 21, 2006
    #5
  6. midwest_46

    Salmon Egg Guest

    Again, there is terminology confusion. I take glare to be s (senkrecht)
    polarized light reflected off of dielectric surfaces, like asphalt, that can
    be partially blocked (totally at the Brewster angle) by viewing through
    properly oriented polarized film.

    Flare is the recording or perception of artifacts in a photograph arising
    from light reflected at the surfaces of lens elements.

    Bill
    -- Fermez le Bush
     
    Salmon Egg, Dec 21, 2006
    #6
  7. midwest_46

    Salmon Egg Guest

    You would lose about 4% of the light at each of the two lens surfaces
    (assuming an index of 1.5) or a total loss of about 8%. The additional
    transmission of light is not really all that useful. It is the prevention of
    the reflected light from generating confusion that is the big benefit.
    Simple one layer AR coatings will reduce the reflectivity to about 1% per
    surface. Multilayer coatings, and I am not familiar with what dispensing
    opticians can do these days, can improve upon that.

    If your lens index goes up to 1.65, the total loss is about 6% per surface.
    Strange as it may seem, single layer coatings will give improved AR
    performance on such lens surfaces up to a lens index of 1.9 compared to
    lower index lenses.

    For monitors, there are other systems for wiping out glare that do not
    require glasses. Retarding waveplate films can be placed in front of the
    screen so that light reflected off of a CRT surface does not get back out.
    Other methods use absorbing screens or meshes that reduce light from
    reflections off of the screen/

    Bill
    -- Fermez le Bush
     
    Salmon Egg, Dec 21, 2006
    #7
  8. Right. This sci.med.VISION, where we use ophthalmic optics terminology,
    not precision camera or instrument terminology. But I still think you
    are using the term glare incorrectly even in that context (see my
    definition below). And I don't know why you are specifying dielectric
    below. What has that got to do with anything? Reflected sunlight off
    any relatively smooth surface anywhere near Brewster's angle will of
    course be polarized, including glass, water, even the atmosphere, which
    is why polarized filters are used under those conditions. We do not use
    the term flare in the eye business, except in the context of warning
    people not to try to observe the solar variety, and to use protective
    eyewear when handling the boating or highway hazard varieties. Your use
    of the term here is showing your, er, obfuscatory flair.

    w.stacy, o.d.
     
    William Stacy, Dec 21, 2006
    #8
  9. i am sure that in eyeglass store lingo the terms anti glare and anti
    reflective are being used interchangeably and refer to the same
    coating.
    at -5 you are probably getting hi index lenses and therefore anti
    reflective coatings become more important or the reflections on the
    lenses will be greater.

    the coatings do increase light transmission thru the lens and therefore
    enable brighter view. the coatings are on both surfaces of the lens and
    therefore offer an esthetic advantage (someone looking at you sees your
    eyes and not a lot of reflection off the lens) and a functional
    advantage (the wearer has less kick or reflection in the lens he's
    looking thru).

    The idea is the AR coating causes the lens interface to more or less
    disappear . look at your self in a mirror with wearing a pair of
    regular lenses and compare with ar lenses. Very obvious difference.
     
    michael toulch, Dec 23, 2006
    #9
  10. midwest_46

    louise Guest

    I find they make a tremendous difference when driving at
    night - oncoming headlights etc. - well worth the money.

    Louise
     
    louise, Dec 29, 2006
    #10
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