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Rx lens range availabilities

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  • Rx lens range availabilities

    The lab at our company provides an availability guide on lenses.
    An example is 1.67 Hi Index Transitions
    sph range +10.00 to -16.00
    cyl range 0.00 to -8.00

    So we place an order for this Rx

    -15.00 -5.50 x 010

    the lab tells us it out of range and when we question the guide, they tell us it's because its total power.
    Am I wrong to believe they need to update the availability guide to reflect what they are saying?
    Sure looks like it should fit into the parameters.


  • #2
    I told the lab according to my calculations the total power would be -20.50 and the chart reflects total power of -24.00.
    Am I incorrect with my interpretation?


    • #3
      They are saying highest sphere power is +10 to -16. That's also the highest combined power. The highest sphere power on a -5.50 cyl would be -10.50. I think that's a pretty typical way of showing power range availability.


      • #4
        Yup, quite common for the highest Sph listed on the Rx availability range to represent the maximum combined power (Sph + Cyl).

        Although there's no law saying so, it's probably safer to presume so since the bigger labs all seem to adhere to this.


        • #5
          Typically guides provide the range of powers that can be surfaced and not intended to imply these powers are stock.

          Base curve, blank thickness and index are the determining factors to develop these guides.


          • #6
            All our lens availability guides from a variety of manufacturers treat the sph as the max available power. The cyl tends to just be the max cylinder power that can be surfaced, rather than showing possible combinations.
            Its done so that it can be understood in both plus and minus cyl form