RGP and large pupils

Discussion in 'Optometry Archives' started by Charles, Sep 23, 2007.

  1. Charles

    Charles Guest

    I love my vision with my RGP contacts, but in low light I'm getting
    starbursts around point sources of light. It has to be quite dark,
    like driving on a country road at night - then lights in the distance
    turn into annoyingly large asterisks. An oncoming car or even a nearby
    streetlight is enough to bring things back. I have this problem
    despite iterating several times with my optometrist and getting the
    biggest possible contacts with a large optical zone.

    Should this problem be solvable? I'm kind of confused because he's
    known about this problem from the begnning, but he's only gradually
    creeped up on bigger and bigger optical zones. Why would anyone not
    want the maximum possible OZ all the time? Cost?

    I'd really like to know if I should keep trying to fix this or if some
    people just have to live with it if they have large enough pupils. Are
    there any other options anyone can suggest? I've read a little about
    macrolens, but the information is limited and I'm not aware of a way to
    find a local doctor willing to fit me.

    --
     
    Charles, Sep 23, 2007
    #1
  2. Charles

    Charles Guest

    Thanks for the reply. The reason I think OZ is because it is so
    obviously related to the size of my pupil. If I'm looking at a far off
    light at night and it's totally dark, it'll have a big starburst. Put
    some car headlights in the mix and it totally sharpens up. I can watch
    the starbursts grow and shrink as the light situtation changes. Would
    this be the case if it were something else? He just recently increased
    the OZ size and it's better, though not fixed. Worse in left eye too.

    At night I can see pretty much the whole perimeter of something (OZ or
    lens itself) in my peripheral vision. Like a halo kind of. That
    itself doesn't bother me much.

    I'll have to experiment with cleaning the lenses and then going out at
    night. It's true that I've always had many hours of wear before these
    night situations arise.

    Okay, so a large OZ is good, but the trade-off is that you have a
    thicker center potentially, and less lens to work with for comformat
    around the edges (if I understand you right). Makes sense.

    So if you were my doctor, what would you try to help fix the problem,
    aside from seeing if cleaning them helps?
     
    Charles, Sep 24, 2007
    #2
  3. Charles

    Charles Guest

    Thanks again for the reply. I have not noticed the starbursts moving
    or varying at all with blinking. The halo effect does move; I can
    "see" the lens sliding down after a blink.
    I'd describe them as asterisks. The point source with many (more than
    four) sharp lines radially out. Totally symmetrical and not a smear.
    I never had anything like this with glasses (Rx typically
    +0.25,1.0x180). It's not at all disabling, just very annoying. I'm
    not sure whether I prefer the contacts or the vertical smear/double I
    get with no correction (though that is WAY better as a result of
    wearing the contacts. My pre-RGP, no-glasses vision was murder at
    night).
    Where are you located? ;)

    --
     
    Charles, Sep 24, 2007
    #3
  4. Charles

    Can you replicate the starbursts at home or in some other controlled
    situation?

    If you are in total darkness and you look at the moon do you see it
    clear? how about very distant lights?

    If you can replicate the effect you can try the effect with your
    glasses on.

    Otherwise you might want to consider that you are getting a reaction
    to the cars coming towards you that is "opening your eyes" wider
    because you are not totally relaxed about night driving?

    Pupil size varys with anxiety and emotional levels you are
    experiencing.

    I would have thought you can buy a very large contact lens that will
    cover all of your iris. For sure in the past i have seen those.

    If it is your pupil size this must be quite a common problem after all

    Andrew
     
    andrewedwardjudd, Sep 24, 2007
    #4
  5. Mike

    Let me educate you here.

    If a contact lens is insufficiently large to cover a large pupil
    diameter then the outer area of the contact lens is then exposed to
    cause some kind of interference with the normal optics you would
    expect.

    I assume you are in any case aware of that?

    I know from my own experience that *during the day* I was able to see
    the spot placed on one of my contact lenses for id purposes. It makes
    sense therefore that at night for a person with large pupils they are
    going to get some kind of effect from the edge of the lens.

    Or perhaps you can educate me otherwise?

    Andrew
     
    andrewedwardjudd, Sep 25, 2007
    #5
  6. The other factor is that he had very poor night vision with glasses.

    Can a human eye actually see well at night for central vision in more
    or less total darkness for these kinds of dim pin point light
    conditions?

    And if he has a highly steeply curved cornea he would never see well
    at night for a large pupil. Could a RGP give an ortho k effect at the
    edge?

    A prescription might be useful here:)
     
    andrewedwardjudd, Sep 25, 2007
    #6
  7. Charles

    Dr. Leukoma Guest

    Your aberration appears to be pupil dependent. It's probably
    spherical aberration. Optics should be able to solve this problem.
    You need to know the size of your dark-adapted pupil and the size of
    the contact lens optical zone. It appears you don't have this
    information.

    The crystalline lens is also a potential source of aberrations,
    although this seems unlikely in your case. There are instruments that
    can measure these aberrations directly. They are called
    aberrometers.
     
    Dr. Leukoma, Sep 25, 2007
    #7
  8. Thru the ages people have described stars as being star like

    Same goes for venus i think?

    But if you look at venus with binoculars you just see a perfectly
    round light source.

    Generally people think of stars as being more like an asterik than a
    round point of light? Even if they might have good acuity, the
    optical quality is not perfect?

    So is the cornea and lens a pure optical shape for all of its
    available ability to allow light to enter the eye or is the central
    area the most successful?

    just wondering here.
     
    andrewedwardjudd, Sep 25, 2007
    #8


  9. Thru the ages people have described stars as being star like

    Same goes for venus i think?


    But if you look at venus with binoculars you just see a perfectly
    round light source.


    Generally people think of stars as being more like an asterik than a
    round point of light? Even if they might have good acuity, the
    optical quality is not perfect?


    So is the cornea and lens a pure optical shape for all of its
    available ability to allow light to enter the eye or is the central
    area the most successful?


    just wondering here

    And i was forgetting but you mentioned it earlier that as the pupil
    opens chromatic aberation becomes an increasingly more important
    factor in human vision

    Some people might just notice that more than others.

    As it happens Charles has a prescription that Roberto Kaplan
    identified as being associated with intolerance and inflexibility and
    lack of patience.

    Perhaps in fact he just sees what most people are seeing?

    It just bothers him that much more?

    Hence your frustration that you cannot help in this case? Ie his
    vision is in fact just normal?
     
    andrewedwardjudd, Sep 25, 2007
    #9
  10. Charles

    Charles Guest

    Thanks for the reply. I still need to do the experiment with cleaning
    my lens in the evening and seeing if it helps. I tend to doubt it
    will, but no harm in trying.

    My night vision was generally excellent at night with glasses, to the
    extent that my astigmatism was properly corrected. That's why I'm
    noticing this so much. I assume this rules out my eyes themselves as
    the problem, as opposed to their interaction with the contacts?

    My optometrist seems to be acting like he's out of ideas, though I'm
    only on my third try (first on the right eye). First out of the chute
    were pretty good, but my left eye had some residual astigmatism. He
    went to stiffer material, which pretty much fixed the astigmatism, but
    the starbursts were terrible. This one has a bigger OZ, and the
    starbursts are now almost equal on both. Tolerable, but somewhat
    annoying.

    Since I can read 20/20 in the exam room, he thinks I'm done, it seems.
    Around here, the optometrists make all their money seling product, so
    are they are disinclined to go into problem solving mode.

    --
     
    Charles, Sep 26, 2007
    #10
  11. Charles

    Dr. Leukoma Guest

    I still need to know the diameter of your dark adapted pupil and the
    optical zone of the contact lenses.
     
    Dr. Leukoma, Sep 26, 2007
    #11
  12. Charles

    lena102938 Guest

    I do not know a lot about RGP , but It sounds like multifocals.
     
    lena102938, Sep 26, 2007
    #12
  13. Charles

    Mike Ruskai Guest

    [piggybacking]

    I didn't respond to the original post, because I have no experience
    with RGP lenses.

    From what you describe, I'd say you're very likely correct about the
    optical zone.

    I noticed the same thing when I tried Focus Night & Day lenses. Star
    images were not in focus at all - looked a lot like typical spherical
    aberration. The size of the OZ for those lenses is not published.
    However, going to 8.0mm with Acuvue lenses produces good results, as
    does the 8.9mm OZ with B&L PureVision lenses (though they are just as
    horribly uncomfortable as the Focus lenses).

    Since your entire lens is only 9.0mm, it's reasonably safe to assume
    that the OZ is much smaller than that of the soft lenses mentioned
    above.

    I think the only real solution for you is to get your pupil size
    measured, and go with a lens size that allows for an appropriate
    optical zone.
     
    Mike Ruskai, Sep 26, 2007
    #13
  14. Charles

    Charles Guest

    Yeah. I don't know this info. If I requested my contact prescription,
    would the OZ be included? I could probably get that fairly easily, but
    they might get irritated if I pushed for more. I kind of doubt he
    really knows my exact dark adapted pupil size. I would have noticed if
    he had done that measurement, right?

    Just in general, do some people have pupils too big to get optimal
    night vision with RGP, or is it normally solvable?

    Thanks.
    --
     
    Charles, Sep 26, 2007
    #14
  15. Charles

    Dr. Leukoma Guest

    I deal with this problem on a frequent basis in patients who have had
    LASIK. Some of these people have 9.0 mm pupils, which doesn't work
    well with a 6.5 mm optical zone. The reason it isn't typically an
    issue with contact lens patients is because the typical contact lens
    optical zone is 7.6 mm or more. Edge flare from RGP lenses at night
    is probably an acceptable side-effect for most people, and it is
    seldom a source of complaint.

    But, if that is indeed an issue with you, it wouldn't be all that
    difficult to design an RGP lens with a 9.0+ mm optical zone. The lens
    would be correspondingly large, too. I have trial lenses like that.
    As well, aberrometry permits me to measure the spherical aberration
    and how lens design affects it. I'm probably one of the few odd-ball
    OD's who fits contacts to reduce higher order aberrations in patients
    who have major problems with them. Hopefully, wavefront generated
    contact lenses will expand the types of aberrations we can treat, such
    as the irregular astigmatism arising from keratoconus.
     
    Dr. Leukoma, Sep 26, 2007
    #15
  16. Mike

    Charles has with the rule astigmatism. You have its *opposite*.

    For some reason you do patiently hang round this board in this
    *virtual* world,

    But Kaplan found that for against the rule there is a lack of
    committment, and a lack of voicing your truth and a lack of love.

    What do you actually get from being here? I cant see you get much
    at all.

    Your time and your life would be better if you spent time elsewhere
    doing what you really really want to be doing. Meanwhile you seem to
    spend a huge amount of time here. And year in and year out too.

    How do habits like this alter your vision? I have no idea.

    I just report the observed facts.

    Andrew
     
    andrewedwardjudd, Sep 26, 2007
    #16
  17. Mike

    Charles does not see blurry and double *with* his contacts

    He sees like that *without* his contacts or glasses.

    Instead in very very low lighting conditions he sees streaks of light
    radiating outwards from a central point. That might be normal for
    most people in very poor light?

    Andrew
     
    andrewedwardjudd, Sep 26, 2007
    #17
  18. Charles

    Ms.Brainy Guest

    Back to smugging? What are YOU doing here? How much Love have you
    received here, Mr Smug?

    I have learned a lot from Mike. I have learned NOTHING from you,
    except a deeper understanding of a megalomaniac flawed mind and the
    nature of smugness. No love from me to you, but much appreciation to
    Mike and his effort to share his knowledge and experience.
     
    Ms.Brainy, Sep 26, 2007
    #18
  19. Charles

    Dr. Leukoma Guest

    Andrew,

    How do you know that Charles has "with-the-rule" astigmatism?
     
    Dr. Leukoma, Sep 27, 2007
    #19
  20. Charles

    Abe Guest

    It is common for people to observe these problems when it is dark,
    especially for people treated with LASIK (as was mentioned before) or
    for people who have a cornea that has some higher order aberrations.
    Contacts and spectacles only correct for low order aberrations, such
    as defocus and cylinder. Some people have higher order aberrations
    (coma, trefoil,...) that cannot be compensated with conventional
    methods. Fortunately during the day these aberrations play no role
    because of a small pupil. At night however when the pupil opens up
    higher order aberrations can distort your vision. There is not much
    you can do, unless you get custom made wavefront corrected plates that
    are inserted in front of your own lens. I don't think these are for
    sale yet.
     
    Abe, Sep 27, 2007
    #20
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