Comparison of Two Toric IOL Calculation Methods

Purpose. To compare two calculators for toric intraocular lens (IOL) calculation and to evaluate the prediction of refractive outcome. Methods. Sixty-four eyes of forty-five patients underwent cataract surgery followed by implantation of a toric intraocular lens (Zeiss Torbi 709 M) calculated by a standard industry calculator using front keratometry values. Prediction error, median absolute error, and refractive astigmatism error were evaluated for the standard calculator. The predicted postoperative refraction and toric lens power values were evaluated and compared after postoperative recalculation using the Barrett calculator. Results. We observed a significant undercorrection in the spherical equivalent (0.19 D) by using a standard calculator (p≤0.05). According to the Baylor nomogram and the refractive influence of posterior corneal astigmatism (PCA), undercorrection of the cylinder was lower for patients with WTR astigmatism, because of the tendency of overcorrection. An advantage of less residual postoperative SE, sphere, and cylinder for the Barrett calculator was observed when retrospectively comparing the calculated predicted postoperative refraction between calculators (p≤0.01). Conclusion. Consideration of only corneal front keratometric values for toric lens calculation may lead to postoperative undercorrection of astigmatism. The prediction of postoperative refractive outcome can be improved by using appropriate methods of adjustment in order to take PCA into account.

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Intraocular lens bicylindric power calculation method: Using both flat and steep K readings to improve intraocular lens power prediction

European Journal of Ophthalmology ◽

10.1177/1120672117754170 ◽

2018 ◽

Vol 28 (5) ◽

pp. 559-565 ◽

Cited By ~ 3

Author(s):

Jorge A Calvo-Sanz ◽

Javier Ruiz-Alcocer ◽

Miguel A Sánchez-Tena

Keyword(s):

Intraocular Lens ◽

Calculation Method ◽

Power Calculation ◽

Spherical Equivalent ◽

Calculation Methods ◽

Power Prediction ◽

Intraocular Lens Power Calculation ◽

Intraocular Lens Power ◽

Lens Power ◽

Intraocular Lens Calculation

Purpose: To compare and analyze the accuracy of the refractive outcomes obtained in intraocular lens power calculation using the classical calculation method with mean keratometry (K) and the calculation method with both K meridians presented in this article. Methods: A total of 62 eyes of 62 subjects who were undergoing cataract surgery were included in this study. Optical biometry was performed using mean K and Haigis formula for classical intraocular lens calculation methods to achieve intraocular lens power; 4 weeks after surgery, prior to medical discharge, subjective refraction was made. Alternatively, intraocular lens power was calculated with bicylindric method using both keratometry readings, obtaining spherocylindrical refractive expected outcomes. Finally, results obtained with intraocular lens calculation methods, bicylindric method, and Haigis formula were compared. Results: Spherical equivalent calculated by classical intraocular lens calculation methods using Haigis formula (H-SE) was −0.027 ± 0.115 D and using bicylindric method (B-SE) was −0.080 ± 0.222 D. Achieved spherical equivalent obtained 4 weeks after surgery (A-SE) was −0.144 ± 0.268 D. Difference between H-SE and A-SE was −0.117 D (p = 0.002). Difference between B-SE and A-SE was not significant (−0.054 D, p = 0.109). Analysis in refraction groups showed a positive correlation between A-SE confronted to B-SE and H-SE (r = 0.313; p = 0.013 and r = 0.562; p < 0.001, respectively). This indicated a reliability in ametropic group prediction of 0.767 in H-SE and 0.843 in B-SE. Conclusion: Intraocular lens calculation with bicylindric method could be more accurate and had more reliability than classical intraocular lens calculation method. Bicylindric method adds astigmatism control and provides a reliable expected spherocylindrical refraction.

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New algorithm for toric intraocular lens power calculation considering the posterior corneal astigmatism

Journal of Cataract & Refractive Surgery ◽

10.1016/j.jcrs.2017.11.008 ◽

2018 ◽

Vol 44 (2) ◽

pp. 168-174 ◽

Cited By ~ 9

Author(s):

Carmen Canovas ◽

Aixa Alarcon ◽

Robert Rosén ◽

Sanjeev Kasthurirangan ◽

Joseph J.K. Ma ◽

...

Keyword(s):

Intraocular Lens ◽

Corneal Astigmatism ◽

Power Calculation ◽

Toric Intraocular Lens ◽

Intraocular Lens Power Calculation ◽

Intraocular Lens Power ◽

Lens Power ◽

Lens Power Calculation ◽

Posterior Corneal Astigmatism

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Microincision cataract surgery with implantation of a bitoric intraocular lens using an enhanced program for intraocular lens power calculation

European Journal of Ophthalmology ◽

10.1177/1120672119877767 ◽

2019 ◽

Vol 30 (6) ◽

pp. 1308-1313

Author(s):

Gilles Lesieur

Keyword(s):

Cataract Surgery ◽

Intraocular Lens ◽

Prediction Error ◽

Power Calculation ◽

Spherical Equivalent ◽

Toric Intraocular Lens ◽

Intraocular Lens Power Calculation ◽

Intraocular Lens Power ◽

Lens Power ◽

Lens Power Calculation

Purpose: To evaluate the potential benefit of a new version of an online toric intraocular lens calculator in eyes implanted with a bitoric intraocular lens. Patients and methods: Retrospective observational comparative study in patients that underwent cataract surgery with implantation of the bitoric intraocular lens AT TORBI 709M (Carl Zeiss Meditec AG, Jena, Germany). Visual and refractive outcomes were evaluated at 1 month after surgery. The selection of the toric intraocular lens power was performed with the software Z CALC 2.0 (Carl Zeiss Meditec AG). The absolute refractive prediction errors for the spherical equivalent and cylinder were calculated and compared with the values that would have been obtained using version 1.5 of the same software. Results: A total of 393 eyes of 276 patients were evaluated. Mean postoperative sphere and cylinder were +0.03 ± 0.54 and −0.19 ± 0.30 D, respectively. A total of 95.67%, 98.22%, and 95.17% of eyes had a postoperative sphere, cylinder, and spherical equivalent within ±1.00 D, respectively. Mean absolute refractive prediction error for spherical equivalent was 0.34 ± 0.27 D with the two versions of the Z CALC software. In contrast, a significantly higher absolute refractive prediction error value for the cylinder was found with Z CALC 1.5 compared to version 2.0 (0.35 ± 0.32 vs 0.28 ± 0.30 D, p < 0.001). The absolute refractive prediction error for cylinder was ⩽0.25 D in 62.3% and 47.5% when using the versions 2.0 and 1.5, respectively. Conclusion: The use of an optimized software for toric intraocular lens power calculation, considering the contribution of posterior corneal astigmatism, improved the astigmatic outcome with a bitoric intraocular lens.

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Lenstar LS 900 versus Pentacam-AXL: analysis of refractive outcomes and predicted refraction

Scientific Reports ◽

10.1038/s41598-021-81146-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Henrique Aragão Arruda ◽

Joana M. Pereira ◽

Arminda Neves ◽

Maria João Vieira ◽

Joana Martins ◽

...

Keyword(s):

Refractive Error ◽

Prediction Error ◽

Mean Absolute Error ◽

Absolute Error ◽

Spherical Equivalent ◽

Refractive Outcomes ◽

Iol Calculation ◽

Median Absolute Error ◽

The Difference ◽

Mean Prediction Error

AbstractAnalysis of refractive outcomes, using biometry data collected with a new biometer (Pentacam-AXL, OCULUS, Germany) and a reference biometer (Lenstar LS 900, HAAG-STREIT AG, Switzerland), in order to assess differences in the predicted and actual refraction using different formulas. Prospective, institutional study, in which intraocular lens (IOL) calculation was performed using the Haigis, SRK/T and Hoffer Q formulas with the two systems in patients undergoing cataract surgery between November 2016 and August 2017. Four to 6 weeks after surgery, the spherical equivalent (SE) was derived from objective refraction. Mean prediction error (PE), mean absolute error (MAE) and the median absolute error (MedAE) were calculated. The percentage of eyes within ± 0.25, ± 0.50, ± 1.00, and ± 2.00 D of MAE was determined. 104 eyes from 76 patients, 35 males (46.1%), underwent uneventful phacoemulsification with IOL implantation. Mean SE after surgery was − 0.29 ± 0.46 D. Mean prediction error (PE) using the SRK/T, Haigis and Hoffer Q formulas with the Lenstar was significantly different (p > 0.0001) from PE calculated with the Pentacam in all three formulas. Percentage of eyes within ± 0.25 D MAE were larger with the Lenstar device, using all three formulas. The difference between the actual refractive error and the predicted refractive error is consistently lower when using Lenstar. The Pentacam-AXL user should be alert to the critical necessity of constant optimization in order to obtain optimal refractive results.

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Intraocular lens power calculations in eyes with pseudoexfoliation syndrome

Scientific Reports ◽

10.1038/s41598-021-98675-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Aleksandra Wlaź ◽

Agnieszka Kustra ◽

Agnieszka Rozegnał-Madej ◽

Tomasz Żarnowski

Keyword(s):

Cataract Surgery ◽

Intraocular Lens ◽

Prediction Error ◽

Absolute Error ◽

Pseudoexfoliation Syndrome ◽

Control Group ◽

Refractive Outcomes ◽

Iol Calculation ◽

Lens Power ◽

And Control

AbstractTo compare refractive outcomes after cataract surgery in pseudoexfoliation syndrome (PEX) and control eyes and to investigate the accuracy of 3 intraocular lens (IOL) calculation formulas in these eyes. In this prospective comparative study 42 eyes (PEX group) and 38 eyes (control group) of 80 patients were included. The follow-up was 3 months. The refractive prediction error (RPE), mean absolute error (MAE), median absolute error (MedAE) and the percentages of eyes within ± 0.25 D, ± 0.5 D, ± 1.0 D and ± 2.0 D of prediction error were calculated. Three IOL calculation formulas (SRK/T, Barrett Universal II and Hill-RBF) were evaluated. PEX produced statistically significantly higher mean absolute errors and lower percentages of eyes within ± 0.5 D than control eyes in all investigated IOL calculation formulas. There were no statistically significant differences in the median absolute errors between the 3 formulas in either PEX or control eyes. Refractive outcomes after cataract surgery are statistically significantly worse in PEX than in control eyes. All three IOL calculation formulas produced similar results in both PEX and control eyes.Trial registration: ClinicalTrials.gov registration number NCT04783909.

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The Accuracy of Different Generation Intraocular Lens Power Formulas in Eyes with Axial Length Lower than 22 millimeter

10.21203/rs.2.19177/v1 ◽

2019 ◽

Author(s):

Aydın Yildiz ◽

Sedat Arikan

Keyword(s):

Intraocular Lens ◽

Axial Length ◽

Statistical Significance ◽

Absolute Error ◽

Accurate Estimation ◽

Intraocular Lens Power ◽

Significant Difference ◽

Iol Calculation ◽

Iol Power ◽

Lens Power

Abstract Background:To investigate the accurate formulas for eyes with axial length (AL) lower than 22 millimeters among usually used six intraocular lens (IOL) calculation formulas. MethodsA total of 122 eyes with short ALs that is lower than 22 mm of 122 patients who underwent phacoemulsification surgery with the same type of IOL implantation were included in this retrospective study. The biometric values of the patients were obtained by using optical low coherence reflectometry (OLCR) for six formulas involving Hoffer Q, SRK-T, Haigis, Barett Universal II, Holladay 2 and Hill-RBF. All patients had a postoperative best corrected visual acuity level that is equal or higher than 20/40. While comparing the accuracy of these six IOL calculation formulas, the mean absolute error (MAE), and the median absolute error (MedAE) values were taken into account.ResultsThe MAE values for Hoffer Q, SRK-T, Haigis, Holladay 2, Hill-RBF and Barrett Universal II formulas were 0.390, 0.390, 0.324, 0.327, 0.331 and 0.208 respectively. Also the rank of MedAE values for the mentioned formulas was 0.245, 0.310, 0.310, 0.250, 0.255 and 0.190. The lowest MAE and MedAE value was found in Barrett Universal II formula, whereas the highest one was in the SRK/T formula with a statistical significance (p<0.001). After Bonferroni correction, there were no statistically significant difference between Barret Universal II formula and the other formulas except SRK/T (p>0.01). Three patients (2.5%) were in the ±0.75 D range, 15 patients (12.3%) were in the ±0.50 D, and the remaining 104 (85.2%) patients were in the ±0.25 D at the first month follow-up. ConclusionsAlthough Barrett Universal II appears to be the most accurate IOL calculation formula, third, fourth and other newer generation formulas have also a good predictive value for accurate estimation of IOL power in short eyes.

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