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Eye Measurements - Ophthalmology Equipment to determine best IOL

Posted , 4 users are following.

julie66167
julie66167

I have read a bit about each of the following pieces of equipment but am having difficulty understanding their exact use. I would like to ask the next ophthalmologist I see which equipment they use. Do you think this will be acceptable?

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IOL Master 700

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Pentacam

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Lenstar LS 900

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Alcon ORA

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Alcon Argos

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I will also ask which IOL formula they use. I hope I find an excellent surgeon who is understanding.

I still am not certain that the Light Adjustable Lens has the quality vision that I would like. Back to the beginning.

Thank you - this forum is the best. Thank you RonAKA for the post on IOL Power Calculation Formulas.

0 likes, 4 replies

4 Replies

  • Lynda111
    Lynda111 julie66167

    Edited

    Yes. Ask your cataract surgeon whatever you wish.

    It's good to be a well-informed patient so you can intelligently discuss your surgery, and to keep your doctor on his or her toes.

  • RonAKA
    RonAKA julie66167

    Edited

    IOLMaster 700

    Lenstar LS-900

    Alcon Argos

    .

    These are all optical methods of measuring the eye dimensions with the axial length being the most critical value. From what I know, they are all good, but I had never heard of the Alcon Argos until very recently, and I know the least amount about it. I also have not seen this one in use at the hospital or surgeon's clinic, or at the two Lasik specialists that I saw. Perhaps it is new. The advantage of the IOLMaster 700 is that it only takes about half the time to take a measurement. When you go through this measurement process you do have to hold your eye open without blinking for some time - from memory perhaps 90 seconds with the Lenstar. I think the solution they use if you blink is to retake the measurement. So, at the end of the day the IOLMaster is probably faster, but if they take the time to get a good reading the Lenstar is also going to work. The IOLMaster 700 has a number of calculation formulas built in, and more can be added. It also takes some slope measurements to measure astigmatism.

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    Pentacam

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    This instrument measures the topography of the cornea and as a result the astigmatism. I believe this is a more advanced method to diagnose and measure astigmatism. It can display a coloured map of the eye using different colours. It makes it easy to see if the astigmatism is symmetrical or irregular. This is typically used in combination with one of the eye dimension instruments.

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    Alcon ORA

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    This is a method of measuring the dimensions of the eye during surgery after the natural lens is removed but before the IOL is inserted. The final lens power selection is made after this measurement is done in real time during the surgery. It may be of most benefit with dense cataracts, but I have not done a lot of checking into it.

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    If I was doing surgery again my choice would be the IOLMaster 700 and Pentacam, combined with the Hill-RBF 3.0 and Barrett Universal II formulas. That would be with kind of standard eyes. If one has post Lasik eyes, then things become a lot more complicated, and I think it would be best to find a surgeon that specializes in measuring and doing those eyes. And, if ones eyes are really short or long then there may be better formulas. The Hill calculator will issue warnings if the eye dimensions fall out of the range that it is suitable for.

  • julie66167
    julie66167

    Posted

    I called an ophthalmologist's office and asked about the equipment for measuring prior to cataract surgery. This surgeon has the latest Alcon IOL Master, not sure of the number. He does not use the Pentacam. He uses the iTrace. Is it better?

    • RonAKA
      RonAKA julie66167

      Edited

      The latest IOLMaster is the 700 model, the older one is the 500. The 700 is supposed to be better at getting accurate measurements on more dense cataract eyes, and I believe has more capability to load in multiple IOL calculation formulas. On a quick read of one article comparing the two instruments the Pentacam HR and iTrace are not equal. Their conclusion:

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      "We concluded that these different devices agreed on measurements of the magnitude and angle of steep and flat meridians, horizontal and oblique astigmatism, and horizontal and vertical coma corneal aberrations. However, the devices produced different pupil size measurements and fourth-order spherical aberration results. Therefore, these instruments cannot be used interchangeably in refractive surgery."

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      This article is somewhat above my pay grade, but my thoughts are that for calculating IOL powers and astigmatism correction they are equal. That is based on my observation that pupil size and higher order spherical aberrations are not considered in the basic IOL power calculation formulas. There may be need for these other measurements that I am not aware of. My thoughts are that the Pentacam HR version is probably the better instrument, but the newst iTrace may be better than the older Pentacam instruments. Just a quick opinion based on one article from 2022.

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      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8951144/pdf/vision-06-00018.pdf

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