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
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
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
