Abstract
Purpose of Review
To provide a glimpse into some of the newer methods of performing IOL calculations and recent literature on which formulas and calculation strategies have been recommended for a certain subset of eyes.
Recent Findings
A literature review was performed to investigate all the relevant, recently published studies on the progress, comparisons, and recent advancements of IOL calculations. Based on this review, the appropriate history, evolution, progress, limitation, and recent advancements are analyzed and explained. A plethora of IOL formulas and calculation strategies have been developed to help surgeons achieve the most desired post-operative outcome for their patients.
Summary
Modern IOL formulas, calculation strategies, and biometric devices perform well for average eyes; however, they remain less optimal for eyes with atypical biometric parameters. There is no single solution that has been deemed as the perfect formula which can simplify the process and consistently provide accurate results for all types of eyes. Over the years, a number of different formula optimization strategies have been devised for traditional IOL formulas and newer, more sophisticated IOL formulas with advanced mathematical algorithms have been developed. By addition of new input parameters and use of complex mathematics to better estimate post-operative lens position, these solutions may minimize refractive error. These methods may provide increasing improvement in both typical and atypical eyes in the years to come.
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References
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
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•• Ladas JG, Siddiqui AA, Devgan U, Jun AS. A 3-D “super surface” combining modern intraocular lens formulas to generate a “super formula” and maximize accuracy. JAMA Ophthalmol. 2015;133:1431–6. https://doi.org/10.1001/jamaophthalmol.2015.3832 This study describes a novel method of representing IOL formulas in 3-D, and describes the derivation for the IOL “super formula” from the “super surface.”.
• Kane JX, Heerden AV, Atik A, Petsoglou C. Intraocular lens power formula accuracy: comparison of 7 formulas. J Cataract Refract Surg. 2016;42:1490–500. https://doi.org/10.1016/j.jcrs.2016.07.021 This study compares accuracy of 7 IOL formulas (Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Holladay 2, SRK/T, and T2) using IOLMaster biometry and optimized lens constants.
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•• Melles RB, Holladay JT, Chang WJ. Accuracy of intraocular lens calculation formulas. Ophthalmology. 2018;125:169–78. https://doi.org/10.1016/j.ophtha.2017.08.027 This study compared the accuracy of several IOL formulas (Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Holladay 2, Olsen, and SRK/T) in a large cohort of eyes which received two different types of lens implants.
• Popovic M, Schlenker MB, Campos-Möller X, Pereira A, Ahmed IIK. Wang-Koch formula for optimization of intraocular lens power calculation: evaluation at a Canadian center. J Cataract Refract Surg. 2018;44:17–22. https://doi.org/10.1016/j.jcrs.2017.09.035 This study evaluated the Wang-Koch axial length adjustment to the Holladay I formula and elucidated the range of axial length where it would be most beneficial.
•• Kane JX, Van Heerden A, Atik A, Petsoglou C. Accuracy of 3 new methods for intraocular lens power selection. J Cataract Refract Surg. 2017;43:333–9. https://doi.org/10.1016/j.jcrs.2016.12.021 This study compares three new methods (Hill-RBF, FullMonte, and the Ladas Super Formula) of performing IOL calculations in addition to comparing these methods to Holladay I and Barrett Universal II formulas.
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Uday Devgan reports other from Advanced Euclidean Solutions outside the submitted work. In addition, Dr. Devgan has a patent Advanced Euclidean Solutions pending. Aazim A. Siddiqui declares that he has no conflict of interest.
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Siddiqui, A.A., Devgan, U. Mastering Lens Calculations: New Formulas and Comparisons. Curr Ophthalmol Rep 6, 233–236 (2018). https://doi.org/10.1007/s40135-018-0186-z
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DOI: https://doi.org/10.1007/s40135-018-0186-z