RGP starburst effect at night

Discussion in 'Optometry Archives' started by Charles, Aug 17, 2006.

  1. Charles

    Charles Guest

    What causes this? Is it the pupil opening up wider than the optical
    zone of the lens (if I'm using that term correctly)? Does a larger
    lens imply a larger OZ? I ask because I got some bigger lenses to
    address some annoying edge effects - and I thought that night vision
    might improve too - but in fact it seems to be noticeably worse. I get
    quite distracting starbursts around lights, and if something is backlit
    and dim (like at dusk) the light bleeds into the dark and makes it hard
    to see.

    Assuming this isn't edema (it doesn't match the descriptions I've read,
    which were more like colored halos) are there any parameters that can
    be adjusted to try to address this? Is this likely to be less of a
    problem with soft contacts?

    Charles, Aug 17, 2006
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  2. Charles

    Ace Guest

    Do glasses cause the same? RGPs are supposed to give better vision, not
    Ace, Aug 17, 2006
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  3. Charles

    p.clarkii Guest

    possibly the edge of the lens is too close to the pupil thereby
    creating a flare effect. the len could be made larger or the base
    curve steepened to center the lens better to counter this effect.
    not necessarily.
    p.clarkii, Aug 17, 2006
  4. Charles

    Jan Guest

    Charles schreef:
    Not necessarily so and some lens designs have a OZ nearly the same size
    as the total diameter of the RGP lens.

    However in some older lens designs there is more or less a relation
    between the total diameter of the lens and the OZ.

    A professional fitter can use a change in this relation do fit the lens

    I ask because I got some bigger lenses to
    Maybe your fitter changed the total diameter and kept the OZ the same size.
    If this is the case then you also noticed that your lens moves more.

    I get
    It is possible that your lens "low rides" due to the more lose
    fitting.(more weight of the contactlens due to the greater total diameter)

    It is also possible (in higher minus lenses) your lens just 'high rides'

    It's also possible that your fitter have changed your lens design also.

    There are lots of other possibilities to explain BTW.
    Yes, several but you need a fitter (face to face) to observe what is
    wrong with the fitting to get the correct contactlenses.

    Is this likely to be less of a
    In general, yes

    Jan (normally Dutch spoken)
    Jan, Aug 17, 2006
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