More monocular diplopia confusion--curiosity question

Discussion in 'Optometry Archives' started by Repeating Rifle, May 31, 2004.

  1. To summarize, I recently (Dec 2003) had cataract surgery. Before and after
    the surgery, a single point source looked like multiple points as seen in an
    uncorrected eye. It resembled the appearance of a starburst firework in
    which stars shot out with spherical symmetry. A traffic light would present
    multiple images. The spectacle lens fitted to that eye merged all the
    individual images into one image.

    Now, instead of getting a spherical distribution of images, they tend to
    line up in a horizontal line. The same corrective lens still merges them
    into one image.

    I conclude that my corneal shape has changed. I had used the analogy that
    the cornea was acting like a fly's eye lens with a single retina. Each
    "lenslet" produces its own image. Nevertheless, I am left confused as to
    just what is happening anatomically. It is a curiosity question, because
    there is no ultimate degradation of my vision from this cause, as far as I
    can tell.

    What causes the cornea to change shape on such a small local scale? Just how
    does a single corrective lens overcome the fly's eye effect?

    Bill

    ******************************

    Here are copies of some previous posts on the subject:

    I am two years younger than you. My background is in optics but not
    optometry. I have posted on this subject here before without getting much in
    the way of helpful suggestions.

    Recently, I had cataract surgery on an eye that pretty much the way you
    describe. Without glasses, a point source appeared to become a starburst of
    multiple points. That persisted after surgery. This told me that the
    distorting crystalline les was not the source of these extra images. I could
    see more than six images of a traffic light of various intensities. I
    mentioned it to my opthalmologist. He said to ignore the problem until I was
    fitted with new glasses. Then If there still was a problem, he would look
    into it. The problem went away with my new glasses. He was very pragmatic
    and did not want to speculate on what the cause might be on a non-problem.

    This left the cause unresolved in my mind. I came to the conclusion that the
    cornea of that eye had a series of lenslets, each producing its own image.
    Although I have not figured out the detailed explanation, stopping part of
    the eye with a finger would eliminate some of those images. It as if the
    cornea was polygonal rather than spherical in the first approximation.

    Again, without understanding the details, I analogize it somewhat to the
    focussing screens used in some reflex cameras. The screen acts as a ground
    glass for observing the image formed upon it by the lens. Thus, no matter
    how it scatters, the light leaving it gets focussed by the crystalline lens
    onto the retina. If the image is not formed at the screen, then the various
    prisms and other perturbations on the screen enhance the blurriness. This
    makes it possible to get better focus accuracy.

    Bill
    *****

    I am pretty sure that the astigmatism was present before as well as after
    the surgery.

    I had come to the conclusion that I was getting multiple focal points. The
    appearance of point sources were more like what I would expect from an array
    of separate lenses--a fly's ey but with a single retina. Simple cylindrical
    error will not do that.

    Bill
     
    Repeating Rifle, May 31, 2004
    #1
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  2. Repeating Rifle

    Guest Guest

    Bill,

    I clearly know a lot less about optics than you do and I can't attempt to
    directly answer your questions. However, you and the group might be
    interested in my (minimal, but hopeful) progress. One answer to the msg. I
    posted and you quoted (below) was from Mike Tyner, OD. He recommended a
    test with a pinhole and after I responded he recommended that as a first
    step I have the cornea topology measured, specifically using an Alcon Laser.
    I had previously located a Dr. who had published quite a bit on monocular
    diplopia and I had Emailed him asking for advice. His reply arrived after
    Mike's - his recommendation was essentially identical. He also steered me
    to a nearby Dr. who has the correct equipment and I have an appt. for the
    exam on 6/23.

    Experimenting with a pinhole I discovered that the "ghost" image was
    brightest when the pinhole was near the top of the iris and somewhat towards
    my nose - say at 11 o'clock (as I see it, right eye). This prompted me to
    examine that area in a mirror, with magnification. I discovered that there
    is a visible irregularity extending from the sclera into the edge of the
    iris, in an area normally covered by my eyelid. My wife examined it, said
    it "looks like a piece of egg white" and she had known it was there, just
    assumed I knew it too. She thought it was a result of a stitch put in when
    I had lens implant. I strongly suspect that this is connected to the
    distortion of the cornea, although the part that I can see doesn't extend
    into the pupil, even at greatest dilation.

    I'll let you know what I find out. Good Luck!!!

    Bob Peyton
     
    Guest, Jun 2, 2004
    #2
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  3. Repeating Rifle

    Guest Guest

    Bill,

    Mike Tyner suggested several possible diagnoses. Looking them up on the
    net, my condition looks a little like pterygium, but there are no blood
    vessels, not even any redness, leading to the growth tissue, so I doubt if
    that is the problem. My wife says she remembers (she's ten years younger
    than me and remembers better ;]>) that the stitch after the lens implant was
    in the location of the present growth.

    I am worried about it, but I put as much pressure as I could on the
    doctor's office, and I am still 3 weeks from an appointment.

    Thanks for your interest.

    Bob
     
    Guest, Jun 3, 2004
    #3
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