Spectacles normal tilt

Discussion in 'Optometry Archives' started by Peter C, May 10, 2009.

  1. Peter C

    Peter C Guest


    I don't know if tilt is the right word. But I'll describe it. When you
    see a person wearing eyeglasses from the side
    view, the glasses as seen from the sides may be slanted.
    Is slant normal? My spectacles has the upper part further away from me
    than the lower part.. or if seen from sides, the eyebrow part is
    further from glasses than lower part from glasses, can you imagine it?
    Is it normal? Or is normal the upper and lower part same distance from
    the eye socket? Thanks.

    Peter C, May 10, 2009
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  2. Peter C

    Peter C Guest

    But I spent most time with it looking at computer monitor
    straight ahead, is it ok to adjust it so it's not slant but
    directly vertical??


    Peter C, May 10, 2009
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  3. Peter C

    Neil Brooks Guest


    Out of curiosity, Mike, is there a strength of prescription beyond
    which a wearer altering panto- WILL unwittingly alter their vision,

    In other words, as a high plus, if I push my glasses up the bridge of
    my nose, or pull them away from my eyes ... the scenery changes ...

    Does panto- have real-world effects for Rx's beyond ... a certain
    point ... or bifocals ... or ... anything with high cyl ... or ... ?
    Neil Brooks, May 10, 2009
  4. Peter C

    mpace99 Guest

    It is normal to have a 10 to 15 degree tilt. This is called
    pantoscopic tilt and serves to reduce aberrations in the lenses.

    mpace99, May 10, 2009
  5. Peter C

    Salmon Egg Guest

    I am not a vision professional. The optics of the situation is that a
    small tilt will not be detrimental. Large tilts will introduce (lens
    designer not optometric) astigmatism. That is,aspherical lens will no
    longer converge a spherical wave to a single point focus.

    Salmon Egg, May 10, 2009
  6. Peter C

    Salmon Egg Guest

    I do not understand this at all. I can possibly picture this tilt
    optimizing vision by substituting one aberration for another. Certainly
    an on-axis aberration, like spherical aberration, will be minimized by
    looking down the symmetry axis of the lens. I also can see that tilting
    the lens a lot might compensate for some astimatism.

    Salmon Egg, May 10, 2009
  7. Peter C

    Peter C Guest

    Interesting. Do you know a guy called Scott Summers. He can
    emit laser beam from his eyes, i wonder what does it get the
    energy from. Also does it work from eyeball or from the optic
    nerves inside his eyes. They called it Optic Blast. You may be
    one of the eye doctor reserved for him. Scott Summers friends
    are the Wolverine, Storm, maybe you got the idea...


    Peter C, May 10, 2009
  8. Peter C

    The Real Bev Guest

    Somebody, maybe his agent, said Lance Armstrong is so good because he LIKES
    pain. I think there's a correlation here...
    The Real Bev, May 11, 2009
  9. Peter C

    Mark A Guest

    Unfortunately, that is not the main reason. The reason he is so good (at
    least a big factor) is that his heart is (literally) 1/3 larger than a
    normal human heart. He was a tri-athlete before taking up cycling full time.

    My heart is normal, so I am justified in sitting on the couch and watching
    sports on TV.
    Mark A, May 11, 2009
  10. Peter C

    The Real Bev Guest

    Yeah, but there are a lot of people with superb physical attributes. I think
    more is needed for world-class performance -- and a love of pain just might do
    the trick!
    I figure 8 miles of bicycling a day is my couch-potato dues. Or computer-chair

    Cheers, Bev
    "The last thing you want is for somebody to commit suicide
    before executing them."
    -Gary Deland, former Utah director for corrections
    The Real Bev, May 12, 2009
  11. Peter C

    Salmon Egg Guest

    I am not a vision professional.

    This points out that the changes to the effective lens are proportional
    to the SQUARE of angle between the lens symmetry axis and the viewing
    direction. Moreover, the greater the power of the corrective lenses, the
    more sensitivity to the effect of panto. This effect will be asymmetric
    with respect to looking up to looking down.

    Although not explicitly pointed out. the context indicates angles are
    measured in degrees and not radians.

    Salmon Egg, May 12, 2009
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