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Thread: Academic question where you can show off your knowledge. Please do!!!

  1. #1
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    Confused Academic question where you can show off your knowledge. Please do!!!

    Academic Senario: :shiner: I know it's a long one, but I am desperate!!!
    the RX OD +3.00 -4.00 x120 / OS +1.50 -3.00 x045. PD 64
    Frame measurements 56/14 Aviator Shape.

    I make the glasses and they check out perfectly. The patient trys to get use to the new rx but felt uncomfortable. The patient returns to the dr instead of me. The dr. assistant checks the glasses and says the PD is at 74, off by 10mm and there is 1^BU prism. The patient returns to me with a note from the Dr. that says "Dear Optician...fix it."

    The questions that follow the assignment are: Can you fix it? SHould you fix it? Stuff like that. (trying to get us to look deeper than the surface.)

    When I did the calculations (power at 180 and 90) I found;
    OD 0.00@180 and +2.00@90
    OS 0.00 @ 180 & 90.
    {D = DSph + DCyl (sin^)2} formula

    (THE INSTRUCTOR STRICKLY WANTS US TO DEAL WITH THE FACTS GIVEN IN THE SENARIO, :finger:NO ASSUMPTIONS ARE TO BE MADE.) This is where my problem comes in.

    1. Can you tell me the only way you can verify the PD of this kind of RX? I am completely stumped here, no ideas!!!

    2. And why is there vertical imbalance?
    [I have already submitted answers of the following... 1. Dr. assistant checked them incorrectly in the lensometer according to ANZI Standars. 2. The OC could be sitting 5mm above the patients line of sight. 3. The patient could be experiencing Anisometropic problems (difference in power between the eyes that may cause differing amounts of prism when the wearer looks off center, as in reading.), 4. The prism dial could have been bumped between lenses or frame table moved accidently. ]

    The instructor says there are more reasons????:angry: WHAT ARE THEY??????
    He says "There is also something else that can cause vertical imbalance especially in this RX." <direct quote. Well, I can't think of any more!!!
    Can anybody else???

    3. And finally, what do you percieve to be the problem? WHy? (this question is especially difficult one for me to remember the stipulation that you must to ONLY go off the facts given in the senario.:finger: )

    Please let me assure you that I am not looking for an easy way out of this assignment. I take my education very seriously. But I am truly stumped. I have communicated back and forth with the instructor and I am getting nowhere with him. I've talked to all the Optician in my office, even some of the doctors and all I got was blank stares.
    My brain is frying as I type this.
    PLLLLEEEEAAASSEE give it a shot. Let me know if you can give ANy input into ANY of these questions. I would greatly appreciate it!!!
    (can you tell I'm begging???)

    Desperate for some Optician wisdom,

    TracyElise:o

  2. #2
    ATO Member HarryChiling's Avatar
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    When I did the calculations (power at 180 and 90) I found;
    OD 0.00@180 and +2.00@90
    OS 0.00 @ 180 & 90.
    {D = DSph + DCyl (sin^)2} formula
    If the left lens were to be measured in a lensmeter since the lense has a plano power at the 180 and the 90 the OC could be just about anywhere on those meridians and look like they fall within the center of your lensmeter. But since the right eye has power in the 90th meridian than you will potentially see a prism imbalance if you were to check the left eye first. If yo were to dot up the right eye first and then the left the prism imbalance would dissappear. It is the correct way of verifying the Rx to mark up the highest power first. Since neighther lense has power at the 180 this can contribute to the fact that PD measures are inaccurate. I would mark the lenses with the pd as 64mm and check that the prism at these points are accurate to ANSI standards. Please let me know if this helped.
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