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Double-K method to calculate IOL power after refractive surgery

Rosa, Nicola MD; Capasso, Luigi MD; Lanza, Michele MD

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Journal of Cataract & Refractive Surgery: February 2005 - Volume 31 - Issue 2 - p 254-255
doi: 10.1016/j.jcrs.2004.12.014
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We read with interest the article by Dr. Aramberri.1 We would like to congratulate his great effort in trying to solve one of the main problems we will face in a near future: calculating intraocular lens (IOL) power in eyes that have had refractive surgery.

We tried to use the formula reported in Appendix. This was difficult until we figured out there were errors. We would like to point these out so others will not have the same problems.

  1. In equation 4, rpre2 and Cw2/4 should be changed to rpre2 and Cw2/4 so that

  2. will be changed to

    Moreover, if [rpre2 − (Cw2/4)] is < 0, the value obtained should be 0.
  3. In equation 10, n should be changed in na so that

  4. will be changed to

  5. In equation 5 is the variable ACDconst, which the author says equals the “IOL constant (can be computed from A-constant).” We suggest specifying that ACDconst=0.62467 × A − 68.74709, where A=SRK constant.

Although these may seem to be insignificant changes, they will make a difference to those trying to use these formulas. This will prevent this interesting study from being marred by printing mistakes.

Nicola Rosa MD

Luigi Capasso MD

Michele Lanza MD

Naples, Italy


1. Aramberri J. Intraocular lens power calculation after corneal refractive surgery: double-K method. J Cataract Refract Surg 2003; 29:2063-2068
© 2005 by Lippincott Williams & Wilkins, Inc.