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Thread: mono pd's using pupilometer

  1. #1
    Bad address email on file Rich R's Avatar
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    mono pd's using pupilometer

    I see quite a few mono p.d's that are 5 to 6 mm difference, like 28 / 34 sent to our lab. Back when I used to take mono p.d's the old fashioned way with p.d. rule.
    1st measuring binocular, then from center of bridge to right pupil and then from center of bridge to left pupil, it wasn't perfect, but with double checking by marking the demo lenses it usually worked out well.
    I just don't remember p.d's being up to 6mm difference as often as I see it nowadays.
    Thoughts?

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    opti-tipster harry a saake's Avatar
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    Lightbulb pd,s

    :D Rich, if you will look in the tips on dispensing thread, you will see a couple of tips i wrote about this and also some replies from David Wilson and others.
    .....It is not out of the question to see these kind of pd,s on occasion, but whenever you do you should certainly double check using the two other methods as you describe.
    .....Part of the problem with pupilometers is they have tendency to not sit accurately on the nose, and more especially when you have a highly irregular type of nose. When this happens you can easily obtain a false reading.
    .....Example, if the patient has a fatty type tissue on the left side of the septum area, the tendency of the pupilometer will be to sit more to the right then what it should, thus giving you a lower reading on the left then what actually may be.
    .....I still think the best way is to sit the patient down and do a complete adjustment on the frame prior to lens fabrication. Then you will know how they will like to wear it and you can measure accordingly.
    .....Because the pupilometer sits on some portion of the nose does not mean that the nose pads will do the same.

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    Am I wrong?

    In fifteen years, I've yet to trust a pupillometer. I adjust the frame to the patient and dot up the demo lenses with a marking pen.

    I get highly satisfactory results. This is the technique each of my staff is trained to implement. It isn't tough to teach and they really get good with practice in almost no time flat.

    I don't get it...why are pupillometer's so popular?

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    Bad address email on file Rich R's Avatar
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    Thanks for the feedback Harry and Icare.
    Most likely the reason so many use a pupilometer, it's very easy to train some one to use, however if it's being used correctly and not double checked in certain cases is a problem
    Rich R

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    Pupilometers are so popular because we have the dumbing down of America. You will find in the most high tech offices more and more equipement that an idiot can use with five minites training. You can now hire a girl off the street and on her second day she can refract, take K readings, send orders to suppilers, neutralize lenses and inspect glasses (not to mention work out reciepts and the best places to go for lunch with the rest of the office staff.)

    However be of good heart, I once measured all my eyeglass patients with a pupillomeer (about 27) while my work associate used a millimeter rule. When the patient's came back to pick up thier glasses, we reversed the process. We did not find over a millimeter difference on any patients..

    Chip

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    OptiBoardaholic
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    At the risk of repeating my comments on a previous post (and Darryl's). The pupillometer measures the distance between the visual axes very accurately. Unless you are using a pen torch you will not be measuring the viusual axes but the pupil centre (which is not the line we look along). See Ralph Drew 1990 among many others. We have carried out an extensive clinical trial over a period of about 5 years where we have had hundreds of practitioners measure a subject's PD using the dot method, the PD rule and the pupillometer. The results are that the pupillometer PD varied by no more that half a millimeter each eye. The other two methods varied by over 6 mm.
    Sure, some can do this very well but I don't agree with the idea that it is dumbing down. True, people who use a patterless edger may not be able to hand shank a glass lens, but I know which way I would prefer to have my specs made. Optometrists use the latest equipment in their testing, and ophthalmologist use the latest surgical equipment. Why the desire to use outdated technology? All major lens manufacturers now recommend the pupillometer (for a while Sola didn'y but they do now in their latest brochures).
    I wouls ask those who subscribe to the dumbing down, do they have the latest edgers or hand edge all lenses, do use focimeters (possible computerized) or hand neutralize when checking, do they have current diamond point generators or hand roughing?
    Harry makes a good point, though, about variations in monocular PD for some nose shapes (no instrument is perfect).
    Time to get off the soapbox.
    Regards
    David

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    Thanks, Dave.

    Thanks for your objective input. I'll try to remain more open-minded.

    (While I order another box of dotting pens.):D

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    Master OptiBoarder Texas Ranger's Avatar
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    Smilie

    After dispensing since '69, I'd say that I consider the pd rule the least accurate method, especially if there is 1-2 mm disequal monoc pds. and we really want to use visual axis, especially on pals. Also, it is so very important to be aware that we see many monocular seg height differences.

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    Master OptiBoarder Clive Noble's Avatar
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    Re: mono pd's using pupilometer

    Rich R said:
    I see quite a few mono p.d's that are 5 to 6 mm difference, like 28 / 34 sent to our lab. Back when I used to take mono p.d's the old fashioned way with p.d. rule.

    Thoughts?

    Sorry I'm so late on this thread.

    A pupillometer is accurate. However I wouldn't have one in my practice, it's just too clinical.

    I've learned the hard way about mono pds over the last 32 years of fitting PALS.

    Before I even start taking a PD, I chat to the Px both in a standing position and then I ask him/her to sit and carry on the chat.
    I'm not interested in the chat, this is just a carrier to see how the person holds his head, is there a natural tilt? Is he more comfortable with his head to the left (or right)

    In the sitting position I then take a full PD, adjust the frame to the face, and approximately 'dot-up' the demo lenses to the pupil.
    From then on it's just a matter of adjusting the dots to the comfortable position of the pupils and getting the Px to walk with the dotted frame and observe him.

    Of course you have also to take into account his life style and what he wants the glasses to do for him.

    Sorry it's a bit long winded, but the end of the story is that sometimes I come out with Mono PDs of Rt 28 Lt 34 and the pupillometer will tell me its 31/31

    I can assure you the Px is happier with 28/34

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