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      Comparison of astigmatism prediction error taken with the Pentacam measurements, Baylor nomogram, and Barrett formula for toric intraocular lens implantation

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          Abstract

          Background

          To evaluate and compare the astigmatism prediction errors taken with the Pentacam measurements, Baylor nomogram, and Barrett formula for toric intraocular lens (IOL) implantation.

          Methods

          Phacoemulsification with toric Precizon IOL implantation was performed in 41 eyes with corneal astigmatism (range, 1 to 5 diopters (D)) determined by IOLMaster and SimK on Pentacam. Preoperative corneal astigmatism measurements were obtained from IOLMaster readings (IOLMaster, Baylor-IOLMaster, and Barrett-IOLMaster) and Pentacam readings (SimK, Baylor-SimK, Barrett-SimK, wavefront, true net power, total corneal refractive power, and vector derived by manual vector summation using corneal front and back astigmatism). Prediction error and intraclass correlation coefficient (ICC) between the measured (or calculated) astigmatism by IOLMaster and Pentacam and the estimated corneal astigmatism estimated by IOL toricity power and residual astigmatism were determined.

          Results

          The centroid errors in prediction error with IOLMaster, SimK, Baylor-IOLMaster, Baylor-SimK, Barrett-IOLMaster, Barrett-SimK, wavefront, true net power, total corneal refractive power, and vector were 0.59@103, 0.61 @103, 0.37@161, 0.41@162, 0.24@171, 0.36@162, 0.42@106, 0.04@8, 0.07@82, and 0.03@82, respectively, in with-the-rule (WTR) astigmatism eyes at postoperative 3-month. They were 0.22@87, 0.20@74, 0.16@21, 0.54@10, 0.43@3, 0.33@19, 0.51@25, 0.31@58, 0.29@50, and 0.14@50 in against-the-rule (ATR) astigmatism eyes. Of the ten modalities, vector showed the lowest WTR astigmatism prediction error and the highest ICC between the predicted and the estimated corneal astigmatism for both WTR and ATR eyes.

          Conclusion

          Vector summation using anterior and posterior corneal surface power taken with the Pentacam yields the least astigmatism prediction error and is a promising tool for determining toric IOL cylinder power.

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          Most cited references24

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          Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism.

          To evaluate the impact of posterior corneal astigmatism on outcomes with toric intraocular lenses (IOLs). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Case series. Corneal astigmatism was measured using 5 devices before and 3 weeks after cataract surgery. Toric IOL alignment was recorded at surgery and at the slitlamp 3 weeks postoperatively. The actual corneal astigmatism was calculated based on refractive astigmatism 3 weeks postoperatively and the effective toric power calculated with the Holladay 2 formula. The prediction error was calculated as the difference between the astigmatism measured by each device and the actual corneal astigmatism. Vector analysis was used in all calculations. With the IOLMaster, Lenstar, Atlas, manual keratometer, and Galilei (combined Placido-dual Scheimpflug analyzer), the mean prediction errors (D) were, respectively, 0.59 @ 89.7, 0.48 @ 91.2, 0.51 @ 78.7, 0.62 @ 97.2, and 0.57 @ 93.9 for with-the-rule (WTR) astigmatism (60 to 120 degrees), and 0.17 @ 86.2, 0.23 @ 77.7, 0.23 @ 91.4, 0.41 @ 58.4, and 0.12 @ 7.3 for against-the-rule (ATR) astigmatism (0 to 30 degrees and 150 to 180 degrees). In the WTR eyes, there were significant WTR prediction errors (0.5 to 0.6 diopters [D]) by all devices. In ATR eyes, WTR prediction errors were 0.2 to 0.3 D by all devices except the Placido-dual Scheimpflug analyzer (all P<.05 with Bonferroni correction). Corneal astigmatism was overestimated in WTR by all devices and underestimated in ATR by all except the Placido-dual Scheimpflug analyzer. A new toric IOL nomogram is proposed. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
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            A new method of analyzing vectors for changes in astigmatism.

            N A Alpins (1993)
            This method of astigmatism analysis recognizes the need to define an astigmatism goal, thus allowing the surgeon to obtain precise, separate measures of the magnitude and the angle of surgical error. From this, the surgeon can evaluate what surgery may be required to achieve the initial preoperative goal. An index that measures surgical success is adjusted for the level of preoperative astigmatism. The resulting data allow statistical comparison of multiple surgeries and techniques. This method also assists in resolving the case when spectacle and corneal astigmatism do not coincide.
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              An analysis of the factors influencing the residual refractive astigmatism after cataract surgery with toric intraocular lenses.

              To investigate the influence of posterior corneal astigmatism, surgically-induced corneal astigmatism (SICA), intraocular lens (IOL) orientation, and effective lens position on the refractive outcome of toric IOLs.
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                Author and article information

                Contributors
                potatoteam2@gmail.com
                ldhlse@gmail.com
                sungsoon.hwang@samsung.com
                jjulujjulu@hanmail.net
                +82-2-3410-3563 , tychung@skku.edu
                Journal
                BMC Ophthalmol
                BMC Ophthalmol
                BMC Ophthalmology
                BioMed Central (London )
                1471-2415
                24 August 2017
                24 August 2017
                2017
                : 17
                : 156
                Affiliations
                [1 ]ISNI 0000 0001 2181 989X, GRID grid.264381.a, Department of Ophthalmology, Samsung Medical Center, , Sungkyunkwan University School of Medicine, ; #81 Irwon-ro, Gangnam-gu, Seoul, 06351 South Korea
                [2 ]ISNI 0000 0004 0470 4224, GRID grid.411947.e, Department of Preventive Medicine, Graduate School, , The Catholic University of Korea, ; Seoul, South Korea
                [3 ]Department of Ophthalmology, Saevit Eye Hospital, Goyang, South Korea
                Article
                550
                10.1186/s12886-017-0550-z
                5571625
                28836956
                5fa2eb8b-fb27-4f9c-b3c7-0c74d87f6ee7
                © The Author(s). 2017

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                History
                : 26 April 2017
                : 16 August 2017
                Categories
                Research Article
                Custom metadata
                © The Author(s) 2017

                Ophthalmology & Optometry
                astigmatism,toric intraocular lens,corneal posterior astigmatism,pentacam,astigmatism prediction error,vector,iolmaster,baylor nomogram,barrett formula

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