Eyeworld

24 | EYEWORLD | JANUARY/FEBRUARY 2020 ASCRS NEWS Contact Oetting: thomas-oetting@uiowa.edu accurate even when these parameters are not available, as may be the case for surgeons who do not have access to newer biometers. Third, the formula remained accurate across multiple IOL types and materials, which makes its use applicable to a wide range of IOLs. The main limitation of the Kane formula is that it is not yet integrated into current biometers for ease of use. Further studies are needed to show how the Kane formula compares to the other new generation formulas when applied to IOL selec- tion in complicated or premium cataract surgi- cal cases. Also, more data is needed to address which formulas are most accurate at extreme refractive values, such as in extremely myopic or hyperopic eyes. Though in all cases, accu- racy will continue to be limited by the lack of manufacturer precision in the making of IOLs, especially at extreme degrees of ametropia. One question our readers had when review- ing this paper was how the outcomes might be stratified across varying demographics. Dr. Kane did not include detailed demographic data in the study aside from gender and age, making it unclear how the formulas would perform in different populations. Also, the study was limit- ed to uncomplicated cataract surgery cases and did not assess how the different IOL formulas might perform in complicated situations, such as post-refractive eyes, with premium IOLs, or in secondary IOL cases. For uncomplicated surgical cases, there are a number of notable perks to the Kane formu- la aside from its validated accuracy. First, it is easily accessible at IOLformula.com and is free to use. Second, although it is recommended that central corneal thickness (CCT) and lens thickness (LT) be included in IOL calculations for the most accurate results, the Kane team showed that the formula remains significantly continued from page 22 Assessment of the accuracy of new and updated IOL power calculation formulas in 10,930 eyes from the UK National Health Service Kieren Darcy, BM MRCS(Eng), David Gunn, MBBS (Hons I), Shokufeh Tavassoli, MBBS, John Sparrow, D Phil, Jack Kane, MBBS J Cataract Refract Surg. 2020;46(1):2–7. n Results: The study included 10,930 eyes of 10,930 patients with the Kane formula having the lowest mean absolute prediction error (MAE), which was statistically significant (p<0.001 in all cases) followed by the Hill 2.0, Olsen, Holladay 2, Barrett Universal 2, Holladay 1, SRK/T, Haigis, and Hoffer Q. The percentage of eyes within ±0.5 diopters of predicted was Kane 72%, Hill 2.0 71.2%, Olsen 70.6%, Holladay 2 71%, Barrett 2 70.7%, SRK/T 69.1%, Haigis 69%, and Hoffer Q 68.1%. The Kane had the lowest MAE for short, medium, and long axial length subgroups and for each IOL type assessed. The updated versions of the Holladay 2 and Hill 2.0 have resulted in improved accuracy. n Conclusions: Overall and in each axial length subgroup the Kane formula was more accurate than the other formulas. n Purpose: To compare the accuracy of new/ updated methods of IOL power calculation (Kane, Hill 2.0, Holladay 2 with new axial length adjustment) to that of established methods (Barrett Universal 2, Olsen, Haigis, Holladay 1, Hoffer Q, and SRK/T). n Setting: Bristol Eye Hospital, University Hospitals Bristol NHS, Foundation Trust, Bristol, U.K. n Design: Retrospective consecutive case series n Methods: Data from patients having uncomplicated cataract surgery with insertion of one of four IOL types was included. Optimized lens constants were used to calculate the predicted refraction of each formula for each patient. This was compared with the actual refractive outcome to give the prediction error. Subgroup analysis occurred based on axial length and IOL type.

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