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    #16
    The device is called a pd light and meter never widely accepted but very accurate. In the days before implants we had to make post cataract lenses with +12 thru +20 front curves. The measured pd would always be wide on the convex side. No one was interested in the back side measurement. We actually had metal pd rulers with different base curves like +12 +14 +16 to measure the frame so you decenter correctly at least it satisfied our customer. I don’t if it is optically correct but that is what was done.

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      #17
      Originally posted by Lensman11 View Post
      The device is called a pd light and meter
      Here's the actual light that came with it. Made by a Minneapolis Co. Precision-Cosmet.



      I had fun using it on kids after Men in Black came out- I would tell them "this won't hurt a bit... and even if it did you won't remember it".

      Best regards,

      Robert Martellaro
      Attached Files
      Science is a way of trying not to fool yourself. - Richard P. Feynman

      Experience is the hardest teacher. She gives the test before the lesson.


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        #18
        Robert, I heard about "the Grolman" in school about 1987 and it was obsolete even then! You're talking something that's probably 45 years old!

        In essence, you have a corneal reflex pupillometer without the box, right?

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          #19
          The pd light and meter that I have is at least 60 years old. It was made by precision cosmet but if my memory holds if was patented by House of Vision a retail optical chain.

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            #20
            Originally posted by drk View Post
            Robert, I heard about "the Grolman" in school about 1987 and it was obsolete even then! You're talking something that's probably 45 years old!

            In essence, you have a corneal reflex pupillometer without the box, right?
            Right, minus the mirrors and the associated increased functionality. I used this in the 70's- very few frames were glazed at the time, making it a much better system for positional measurements than tape and plastic devices attached to the frame fronts.

            While researching and writing a feature article on presbyopia for the June issue of Vision Monday, I remembered a novel device called the Grolman Fitting System that was once used for fitting patients with progressive lenses. It was, excuse the pun, progressive for its time, though it has since been replaced with modern, digital technologies. Here’s a brief history of the device, drawn from an article I wrote about 25 years ago.


            Originally posted by Lensman11 View Post
            The pd light and meter that I have is at least 60 years old. It was made by precision cosmet but if my memory holds if was patented by House of Vision a retail optical chain.
            Not sure of patents but Benson Optical had one in all or most of their offices. Bensons acquired House of Vision in 1982. HOV did have their own distometer.

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            Both companies were based in Minnetonka and owned by Revlon before they went into GE medical pension, then acquired in 1992 by Martin Franklin, yes, that Marty Franklin. Bensons was essentially bankrupt, and was on the brink of losing the building housing the lab for 180 locations and their home office. Story goes that Franklin just sat down, pulled out his checkbook, and wrote an 8 mil check to buy the building outright.

            The next 4 years were gold for the very earliest investors, but the last year was a living hell for the employees. About 50 of us (out of probably hundreds) acquired legal representation to retrieve back pay and benefits.



            Science is a way of trying not to fool yourself. - Richard P. Feynman

            Experience is the hardest teacher. She gives the test before the lesson.


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              #21
              Does the optical center come into existence in the universe due to the front curve, the back curve, or both curves working together in harmonious optical centrion birthing?

              Perhaps a more entertaining answer would be found from the question; How do the optical centers differ on a digital lens that would inspire one to ask this weird question?

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                #22
                Measure the distance between the pupils of your right and left eyes starting with the right one. The measurement you need is the millimeter that corresponds to your left pupil. Your PD is represented by that number. Note it down.

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                  #23
                  Originally posted by Rodney Elmer View Post
                  Measure the distance between the pupils of your right and left eyes starting with the right one. The measurement you need is the millimeter that corresponds to your left pupil. Your PD is represented by that number. Note it down.
                  Sir, this is a Wendy's.

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                    #24
                    Originally posted by Rodney Elmer View Post
                    Measure the distance between the pupils of your right and left eyes starting with the right one. The measurement you need is the millimeter that corresponds to your left pupil. Your PD is represented by that number. Note it down.
                    When I want to measure my own pd I just run, eyes wide open into my sliding glass door and measure the difference between the center of the splat’s my eyeballs left on it. ( I do measure from right to left too!) no need to note it down though….I just don’t ever wash my glass door. I leave the splat marks on it as future reference when needed. ( It also reminds me not to do that again…)

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                      #25
                      I just do this:

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                        #26
                        This was addressed a few years ago when I was on the Vision Council's Data Communication Standard committee a few years ago. Start at page 25

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