Erratum for “Comparison of Corneal Power Calculation by Standard Keratometry and Total Keratometry in Eyes with Previous Myopic FS-LASIK”

AimsTo provide clinical guidance on the use of intraocular lens (IOL) power calculation formulas according to the biometric parameters.Methods611 eyes that underwent cataract surgery were retrospectively analysed in subgroups according to the axial length (AL) and corneal power (K). The predicted residual refractive error was calculated and compared to evaluate the accuracy of the following formulas: Haigis, Hoffer Q, Holladay 1 and SRK/T. Furthermore, the percentages of eyes with ≤±0.25, ≤±0.5 and 1 dioptres (D) of the prediction error were recorded.ResultsThe Haigis formula showed the highest percentage of cases with ≤0.5 D in eyes with a short AL and steep K (90%), average AL and steep cornea (73.2%) but also in long eyes with a flat and average K (65% and 72.7%, respectively). The Hoffer Q formula delivered the lowest median absolute error (MedAE) in short eyes with an average K (0.30 D) and Holladay 1 in short eyes with a steep K (Holladay 1 0.24 D). SRK/T presented the highest percentage of cases with ≤0.5 D in average long eyes with a flat and average K (80.5% and 68.1%, respectively) and the lowest MedAE in long eyes with an average K (0.29 D).ConclusionOverall, the Haigis formula shows accurate results in most subgroups. However, attention must be paid to the axial eye length as well as the corneal power when choosing the appropriate formula to calculate an IOL power, especially in eyes with an unusual biometry.

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Refractive outcomes of intraocular lens power calculation using different corneal power measurements with a new optical biometer

Journal of Cataract & Refractive Surgery ◽

10.1016/j.jcrs.2018.03.027 ◽

2018 ◽

Vol 44 (6) ◽

pp. 701-708 ◽

Cited By ~ 12

Author(s):

Giacomo Savini ◽

Kazuno Negishi ◽

Kenneth J. Hoffer ◽

Domenico Schiano Lomoriello

Keyword(s):

Intraocular Lens ◽

Power Calculation ◽

Corneal Power ◽

Intraocular Lens Power Calculation ◽

Refractive Outcomes ◽

Intraocular Lens Power ◽

Optical Biometer ◽

Lens Power ◽

Power Measurements ◽

Lens Power Calculation

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An innovative approach for determining the customized refractive index of ectatic corneas in cataractous patients

Scientific Reports ◽

10.1038/s41598-020-73492-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Shiva Pirhadi ◽

Keivan Maghooli ◽

Khosrow Jadidi

Keyword(s):

Refractive Index ◽

Cataract Surgery ◽

Ray Tracing ◽

Prediction Error ◽

Power Calculation ◽

Corneal Power ◽

Iol Power Calculation ◽

Iol Power ◽

Hyperopic Shift ◽

The Difference

Abstract The aim of this study is to determine the customized refractive index of ectatic corneas and also propose a method for determining the corneal and IOL power in these eyes. Seven eyes with moderate and severe corneal ectatic disorders, which had been under cataract surgery, were included. At least three months after cataract surgery, axial length, cornea, IOL thickness and the distance between IOL from cornea, and aberrometry were measured. All the measured points of the posterior and anterior parts of the cornea converted to points cloud and surface by using the MATLAB and Solidworks software. The implanted IOLs were designed by Zemax software. The ray tracing analysis was performed on the customized eye models, and the corneal refractive index was determined by minimizing the difference between the measured aberrations from the device and resulted aberrations from the simulation. Then, by the use of preoperative corneal images, corneal power was calculated by considering the anterior and posterior parts of the cornea and refractive index of 1.376 and the customized corneal refractive index in different regions and finally it was entered into the IOL power calculation formulas. The corneal power in the 4 mm region and the Barrett formula resulted the prediction error of six eyes within ± 1 diopter. It seems that using the total corneal power along with the Barrett formula can prevent postoperative hyperopic shift, especially in eyes with advanced ectatic disorders.

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