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IOL formula offers predictability after refractive surgery
J Cataract Refract Surg. 2008;34(10):1658-1663.
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A new algorithm offers accurate IOL calculations in eyes undergoing cataract removal after previous laser refractive surgery, according to a study.
Wolfgang Haigis, MS, PhD, devised the Haigis-L formula, which is included in the operating software for the IOLMaster 4.0 and later versions (Carl Zeiss Meditec).
The Haigis-L algorithm offers predictable outcomes after laser refractive surgery for myopia based only on current measurements without refractive history.
Data showed that 98.4% of predictions were within 2 D of targeted refraction, 84% were within 1 D and 61% were within 0.5 D. Among eyes without previous refractive surgery, 99.1 % were within 2 D, 93% were within 1 D and 73.4% were within 0.5 D of targeted refraction.
The study is published in the October issue of Journal of Cataract & Refractive Surgery.
In this article, Dr. Haigis publishes the Haigis-L formula and analyzes the effectiveness of the Haigis-L formula in 187 patients. This formula gives fairly accurate predictions for cataract patients who have had prior myopic LASIK and have no pre-LASIK data available. I love it that he hasn’t kept this information proprietary. Often, different formulas give wildly different predictions. It’s nice to know the accuracy of the Haigis-L so we know how much faith to put in its prediction. Seeing Dr. Haigis’ results has increased my confidence in treating these patients.
We need comparative studies to help us know how to rank the importance of these various formulas. In our office, we currently weight formulas for IOL after myopic LASIK as follow: 1. Masket. 2. Haigis-L 3. Aramberri (using the Holladay 1 formula) 4. Shammas 5. Clinical History method (without vertexing) and 6. Latkany (flattest K). Because the Feiz-Mannis usually ends up with the most myopic result, we stay under the IOL-power suggested by this formula. It would be wonderful to have large studies with results that compare the results of these different formulas. It would also be nice to know the Haigis formula to use for post-hyperopic LASIK.
David L. Cooke, MD
Managing partner, Great
Lakes Eye Care