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Wei Y, Liu Y, Li H, Song H. Theoretical Accuracy of the Raytracing Method for Intraocular Calculation of Lens Power in Myopic Eyes after Small Incision Extraction of the Lenticule. Klin Monbl Augenheilkd 2024; 241:221-229. [PMID: 37722612 PMCID: PMC10898958 DOI: 10.1055/a-2177-4998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
AIM To evaluate the accuracy of the raytracing method for the calculation of intraocular lens (IOL) power in myopic eyes after small incision extraction of the lenticule (SMILE). METHODS Retrospective study. All patients undergoing surgery for myopic SMILE between May 1, 2020, and December 31, 2020, with Scheimpflug tomography optical biometry were eligible for inclusion. Manifest refraction was performed before and 6 months after refractive surgery. One eye from each patient was included in the final analysis. A theoretical model was invited to predict the accuracy of multiple methods of lens power calculation by comparing the IOL-induced refractive error at the corneal plane (IOL-Dif) and the SMILE-induced change of spherical equivalent (SMILE-Dif) before and after SMILE surgery. The prediction error (PE) was calculated as the difference between SMILE-Dif-IOL-Dif. IOL power calculations were performed using raytracing (Olsen Raytracing, Pentacam AXL, software version 1.22r05, Wetzlar, Germany) and other formulae with historical data (Barrett True-K, Double-K SRK/T, Masket, Modified Masket) and without historical data (Barrett True-K no history, Haigis-L, Hill Potvin Shammas PM, Shammas-PL) for the same IOL power and model. In addition, subgroup analysis was performed in different anterior chamber depths, axial lengths, back-to-front corneal radius ratio, keratometry, lens thickness, and preoperative spherical equivalents. RESULTS A total of 70 eyes of 70 patients were analyzed. The raytracing method had the smallest mean absolute PE (0.26 ± 0.24 D) and median absolute PE (0.16 D), and also had the largest percentage of eyes within a PE of ± 0.25 D (64.3%), ± 0.50 D (81.4%), ± 0.75 D (95.7%), and ± 1.00 D (100.0%). The raytracing method was significantly better than Double-K SRK/T, Haigis, Haigis-L, and Shammas-PL formulae in postoperative refraction prediction (all p < 0.001), but not better than the following formulae: Barrett True-K (p = 0.314), Barrett True-K no history (p = 0.163), Masket (p = 1.0), Modified Masket (p = 0.806), and Hill Potvin Shammas PM (p = 0.286). Subgroup analysis showed that refractive outcomes exhibited no statistically significant differences in the raytracing method (all p < 0.05). CONCLUSION Raytracing was the most accurate method in predicting target refraction and had a good consistency in calculating IOL power for myopic eyes after SMILE.
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Affiliation(s)
- Yinjuan Wei
- Department of Cataract, Tianjin Eye Hospital, Tianjin, China
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin, China
| | - Yianzhu Liu
- Department of Cataract, Tianjin Eye Hospital, Tianjin, China
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin, China
| | - Hongyu Li
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
| | - Hui Song
- Department of Cataract, Tianjin Medical University Eye Hospital, Tianjin, China
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Juliane M, Anne-Isabel L, Myriam C, Vasyl D, Toam K, J Linke S. Biometry and Intraocular Lens Power Calculation by Combined Scheimpflug-Placido Disc versus Optical Interferometry Devices. J Ophthalmic Vis Res 2022; 17:453-461. [PMID: 36620702 PMCID: PMC9806315 DOI: 10.18502/jovr.v17i4.12349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 03/21/2022] [Indexed: 12/03/2022] Open
Abstract
Purpose To compare the results of the current gold standard, laser interferometry, and keratometry by the IOL-Master, with a newly developed Galilei G6 using raytracing software Okulix for intraocular lens (IOL) power calculations. Methods For comparison of the IOL-power calculation of both devices, we analyzed the difference between the actual one-month postoperative subjective refraction and the theoretically calculated target refraction before cataract surgery. The IOL was selected according to the IOL Master recommendation aiming for emmetropia after surgery.We analyzed the differences of the measurements of the basic biometric data in 205 healthy eyes by each device. Results Our study included 205 healthy, unoperated eyes from 117 patients (61 women, 56 men) aged 20 to 75 years. Twenty-two eyes of cataract patients were also included in this retrospective study design. The mean difference between the prediction of the postoperative refraction and the refraction actually achieved was 0.03 D for the IOL Master and -0.23 D for the Galilei G6. The difference was not statistically significant (P = 0.059). The difference between the IOL power calculation of the IOL Master and the calculation of the G6 was not statistically significant (P = 0.064). The difference between the predicted refraction of the G6 and the refraction achieved after one month was also not statistically significant (P = 0.12) and neither was the difference between the predicted refraction of the IOL Master and the achieved refraction (P = 0.39). The mean axial length was calculated as 24.21 ± 0.80 mm using the IOL Master and 24.27 ± 0.82 mm using the Galilei G6 device. The mean value regarding anterior chamber depth (ACD) of the IOL master was 3.46 ± 0.23 mm and for the Galilei was G6 3.51 ± 0.25 mm. When comparing the white to white (WTW) values of the IOL master, it showed mean values of 12.32 ± 0.31 and Galilei showed mean values of G6 12.21 ± 0.28. All of these differences (between Galileo and IOL Master measurements) were statistically significant (P < 0.001). Conclusion Both the laser interferometry/keratometry performed by the IOL Master and the interferometry/raytracing biometry strategy performed by the Galilei G6 demonstrated equal results when executing the IOL power calculation before cataract surgery in eyes with no prior ocular surgery.
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Affiliation(s)
- Mehlan Juliane
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Lehman Anne-Isabel
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Cichocki Myriam
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Druchkiv Vasyl
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Katz Toam
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany,CareVision Hamburg, Germany
| | - Stephan J Linke
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany,Zentrumsehstärke, Hamburg, Germany
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Chang YC, Cabot F, Heilman BM, Meza L, Ruggeri M, Ho A, Yoo SH, Parel JM, Manns F. Predictability of pseudophakic refraction using patient-customized paraxial eye models. J Cataract Refract Surg 2022; 48:1016-1022. [PMID: 35297814 PMCID: PMC9420759 DOI: 10.1097/j.jcrs.0000000000000934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 03/10/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine whether patient-customized paraxial eye models that do not rely on exact ray tracing and do not consider aberrations can accurately predict pseudophakic refraction. SETTING Bascom Palmer Eye Institute, Miami, Florida. DESIGN Prospective study. METHODS Cataract surgery patients with and without a history of refractive surgery were included. Manifest refraction, corneal biometry, and extended-depth optical coherence tomography (OCT) imaging were performed at least 1 month postoperatively. Corneal and OCT biometry were used to create paraxial eye models. The pseudophakic refraction simulated using the eye model was compared with measured refraction to calculate prediction error. RESULTS 49 eyes of 33 patients were analyzed, of which 12 eyes from 9 patients had previous refractive surgery. In eyes without a history of refractive surgery, the mean prediction error was 0.08 ± 0.33 diopters (D), ranging from -0.56 to 0.79 D, and the mean absolute error was 0.27 ± 0.21 D. 31 eyes were within ±0.5 D, and 36 eyes were within ±0.75 D. In eyes with previous refractive surgery, the mean prediction error was -0.44 ± 0.58 D, ranging from -1.42 to 0.32 D, and the mean absolute error was 0.56 ± 0.46 D. 7 of 12 eyes were within ±0.5 D, 8 within ±0.75 D, and 10 within ±1 D. All eyes were within ±1.5 D. CONCLUSIONS Accurate calculation of refraction in postcataract surgery patients can be performed using paraxial optics. Measurement uncertainties in ocular biometry are a primary source of residual prediction error.
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Affiliation(s)
- Yu-Cherng Chang
- From the Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida (Chang, Cabot, Heilman, Meza, Ruggeri, Ho, Yoo, Parel, Manns); Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida (Chang, Heilman, Meza, Ruggeri, Ho, Yoo, Parel, Manns); Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida (Cabot, Yoo, Parel); Brien Holden Vision Institute Limited, Sydney, New South Wales, Australia (Ho, Parel)
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IOL Power Calculations and Cataract Surgery in Eyes with Previous Small Incision Lenticule Extraction. J Clin Med 2022; 11:jcm11154418. [PMID: 35956035 PMCID: PMC9369542 DOI: 10.3390/jcm11154418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 06/30/2022] [Accepted: 07/27/2022] [Indexed: 02/01/2023] Open
Abstract
Small incision lenticule extraction (SMILE), with over 5 million procedures globally performed, will challenge ophthalmologists in the foreseeable future with accurate intraocular lens power calculations in an ageing population. After more than one decade since the introduction of SMILE, only one case report of cataract surgery with IOL implantation after SMILE is present in the peer-reviewed literature. Hence, the scope of the present multicenter study was to compare the IOL power calculation accuracy in post-SMILE eyes between ray tracing and a range of empirically optimized formulae available in the ASCRS post-keratorefractive surgery IOL power online calculator. In our study of 11 post-SMILE eyes undergoing cataract surgery, ray tracing showed the smallest mean absolute error (0.40 D) and yielded the largest percentage of eyes within ±0.50/±1.00 D (82/91%). The next best conventional formula was the Potvin–Hill formula with a mean absolute error of 0.66 D and an ±0.50/±1.00 D accuracy of 45 and 73%, respectively. Analyzing this first cohort of post-SMILE eyes undergoing cataract surgery and IOL implantation, ray tracing showed superior predictability in IOL power calculation over empirically optimized IOL power calculation formulae that were originally intended for use after Excimer-based keratorefractive procedures.
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Jamali A, Jabbarvand M, Asharlous A, Doostdar A, Bordbar S, Khabazkhoob M. Assessing Accuracy of Okulix Ray-Tracing Software in Calculating Intraocular Lens Power in the Long Cataractous Eyes. J Curr Ophthalmol 2022; 34:67-73. [PMID: 35620361 PMCID: PMC9128429 DOI: 10.4103/joco.joco_136_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 08/28/2021] [Accepted: 09/17/2021] [Indexed: 11/28/2022] Open
Abstract
Purpose To investigate the accuracy of Okulix ray-tracing software in calculating intraocular lens (IOL) power in the long cataractous eyes and comparing the results with those obtained from Kane, Holladay 1 with optimized constant, SRK/T with optimized constant, Haigis with optimized constant, and Barret Universal 2 formulas. Methods The present study evaluates the refractive results of cataract surgery in 85 eyes with axial length > 25 mm and no history of ocular surgery and corneal pathology. IOL power calculation was performed using the Okulix software. The performances of Okulix software in comparison with the five other formulas were evaluated by predicted error, mean absolute error, and mean numerical error 6 months after surgery. Results The mean calculated IOL power by the Okulix software was +13.48 ± 4.19 diopter (D). The mean of the 6-month postoperative sphere and spherical equivalent were +0.18 ± 0.63 and -0.34 ± 0.78 D, respectively. Also, the 6-month spherical equivalent in 56.6% and 80% of eyes were within ±0.05 and ±1.00 D, respectively. The predicted error (P < 0.001) and the mean numerical error (P < 0.001) were different between the six studied methods; however, we were not able to find any significant differences in the mean absolute error among six studied methods (P: 0.211). Conclusion The present study showed acceptable performance of the Okulix software in IOL power calculation in long eyes in comparison with the other five methods based on the postoperative refractive error, calculated mean absolute error, and mean numerical error.
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Affiliation(s)
- Alireza Jamali
- Rehabilitation Research Center, Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Mahmoud Jabbarvand
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Amir Asharlous
- Rehabilitation Research Center, Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Asgar Doostdar
- Rehabilitation Research Center, Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Soodeh Bordbar
- Department of English, Iran University of Medical Sciences, Tehran, Iran
| | - Mehdi Khabazkhoob
- Department of Psychiatric Nursing and Management, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Anders P, Anders LM, Barbara A, Szentmary N, Langenbucher A, Gatzioufas Z. Intraocular lens power calculation in eyes with previous corneal refractive surgery. Ther Adv Ophthalmol 2022; 14:25158414221118524. [PMID: 36061972 PMCID: PMC9434667 DOI: 10.1177/25158414221118524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 07/12/2022] [Indexed: 12/05/2022] Open
Abstract
Intraocular lens (IOL) power calculation after corneal refractive surgery (CRS)
becomes an expanding challenge for ophthalmologists as more and more cataract
surgeries after CRS are required. These patients typically also have high
expectations as to visual performance. Conventional IOL power calculation
schemes frequently provide inaccurate results in these cases. This review aims
to summarize and recommend currently available IOL power calculation methods for
eyes with the most common CRS methods: radial keratotomy (RK), photorefractive
keratectomy (PRK), laser in situ keratomileusis (LASIK), and
small incision lenticule extraction (SMILE). To this end, biometry measuring
methods and IOL formulas will be explained and combinations of both are
proposed. In synopsis, it is evident that the latest generation of vergence
formulas exhibit favorable IOL power prediction accuracy in post-CRS eyes, even
though the predictive precision of methods in eyes without CRS is not attained.
Ray tracing computation, intraoperative aberrometry, and machine learning–based
formulas hold potential to further improve refractive outcomes in post-CRS
eyes.
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Affiliation(s)
- Philipp Anders
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Lisa-Marie Anders
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | | | - Nora Szentmary
- Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Congenital Aniridia Research, Saarland University, Homburg, Germany
| | | | - Zisis Gatzioufas
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
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Nabil K. Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray-tracing software in paracentral corneal scarring not interfering with postoperative refraction. DELTA JOURNAL OF OPHTHALMOLOGY 2022. [DOI: 10.4103/djo_79_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Fernández-Rosés J, Lamarca J, Piñero DP, Barraquer RI. Intraocular lens power calculation in virgin eyes: Accuracy of the Barrett Universal II formula and a Ray tracing software. Eur J Ophthalmol 2021; 32:2954-2960. [PMID: 34854773 DOI: 10.1177/11206721211065552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To compare the accuracy of Sirius ray tracing software with the Barrett Universal II formula for intraocular lens power prediction in virgin eyes. METHODS Retrospective case series including 86 eyes that have undergone uneventful cataract surgery with SN60WF implantation. The median absolute error, mean prediction error, variance, and the percentage of eyes within ± 0.25 D, ± 0.50 D, ± 0.75 D, and ± 1.00 D of the prediction error in refraction were calculated. The correlation of prediction error with different baseline parameters was investigated. RESULTS No differences were found between the median absolute error of the Barrett Universal II formula (0.226 D) and the ray tracing software with different intraocular lens centerings; apex (0.331 D), limbus (0.345 D), and pupil (0.342 D) (p = 0.084). The variance, from lowest to highest, was the Barrett Universal II (0.144 D2), ray tracing-limbus (0.285 D2), ray tracing-pupil (0.285 D2), and ray tracing-apex (0.287 D2) (p = 0.027). The Barrett Universal II formula showed a higher percentage of eyes within ± 0.25 D (56.98%), ± 0.50 D (82.56%), and ± 0.75 D (93.02%) compared to ray tracing software (p < 0.01). A significant correlation between the prediction error of the Barrett Universal II formula and corneal diameter (r = 0.322, p = 0.002) and pupil diameter (r = 0.230, p = 0.033) was found. Also, a positive correlation between the prediction error of Sirius ray tracing and axial length (p < 0.001) and pupil diameter (p = 0.01) was found. CONCLUSION There is a trend of the Barrett Universal II formula to be more accurate than Sirius ray tracing software for intraocular lens power calculation in virgin eyes. This should be confirmed in future prospective comparative studies.
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Affiliation(s)
- Joaquim Fernández-Rosés
- 16360Centro de Oftalmología Barraquer, Barcelona, Spain.,Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - José Lamarca
- 16360Centro de Oftalmología Barraquer, Barcelona, Spain.,Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain.,16760Universitat Internacional de Catalunya, Barcelona, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, 16718University of Alicante, Alicante, Spain
| | - Rafael I Barraquer
- 16360Centro de Oftalmología Barraquer, Barcelona, Spain.,Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain.,16760Universitat Internacional de Catalunya, Barcelona, Spain
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Wang Q, Chen M, Ning R, Savini G, Wang Y, Zhang T, Lin X, Chen X, Huang J. The Precision of a New Anterior Segment Optical Coherence Tomographer and Its Comparison With a Swept-Source OCT-Based Optical Biometer in Patients With Cataract. J Refract Surg 2021; 37:616-622. [PMID: 34506238 DOI: 10.3928/1081597x-20210610-02] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE To assess the precision of a new spectral-domain optical coherence tomographer (SD-OCT)/Placido topographer (MS-39; CSO) and its comparison with a swept-source OCT (SS-OCT) biometer (Argos; Movu, Inc) in patients with cataract. METHODS Fifty-three right eyes from 53 patients were examined by two experienced operators three times using both devices randomly. Employing the within-subject standard deviation (Sw), test-retest variability, coefficient of variation, and intraclass correlation coefficient to evaluate intraoperator repeatability and interoperator reproducibility; the double-angle plots to analyze astigmatism; and Bland-Altman plots and 95% limits of agreement to verify the agreement between devices. RESULTS The SD-OCT/Placido tomographer showed high precision, with coefficient of variation of 0.44% or less, intraclass correlation coefficient of 0.945 or greater for all parameters, test-retest variability of 4.21 µm or less for central corneal thickness (CCT), 0.03 mm or less for anterior chamber depth (ACD) and aqueous depth (AQD), and 0.25 diopters (D) or less for mean keratometry (Km), J0, and J45. The inter-device differences in Km, J0, and J45 were statistically insignificant, whereas the remaining were statistically but not clinically significant. The 95% limits of agreement of CCT, ACD, AQD, Km, J0, and J45 were -3.70 to 15.25 µm, -0.06 to 0.04 mm, -0.06 to 0.04 mm, -0.28 to 0.35 D, -0.27 to 0.26 D, and -0.27 to 0.21 D, respectively. The double-angle plot confirmed the high agreement in astigmatism. CONCLUSIONS For CCT, ACD, AQD, Km, and astigmatism measurements in patients with cataract, the new SD-OCT/Placido tomographer has excellent precision and high agreement with the Argos SS-OCT biometer, and can be used interchangeably. [J Refract Surg. 2021;37(9):616-622.].
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Yu S, Lu CZ, Zhao Y, Song H. Evaluation of a New IOL Power Calculator in Cataract Patients with Normal and Long Axial Lengths. Semin Ophthalmol 2021; 35:370-376. [PMID: 33459110 DOI: 10.1080/08820538.2020.1871033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Purposes: To evaluate the accuracy of Ophtha Top and consistency between Ophtha Top and IOLMaster 500 in intraocular lens refractive power calculation among cataract patients with normal and long axial lengths. Methods: This study included cataract patients scheduled for phacoemulsification and IOL implantation surgery. The IOL power was calculated using Ophtha Top and IOLMaster 500 (integrated with SRK/T, Hoffer Q, Holladay 1 formula). The accuracy of IOL power calculation between Ophtha Top and IOLMaster 500 was compared. Bland-Altman plots were also used to assess agreement between Ophtha Top and IOLMaster 500. Results: Ninety-four patients (94 eyes) were included. The mean values of the arithmetic and absolute prediction errors of Ophtha Top were -0.22 ± 0.62 D and 0.52 ± 0.40 D for whole sample. Absolute refractive error showed no significant difference between Ophtha Top and IOLMaster 500 using 3 traditional formulas in eyes with normal and long axial lengths. In normal eyes, mean and medium absolute error of Ophtha Top was 0.49D and 0.48D, which were comparable to that of IOLMaster 500 (Hoffer Q:0.47D; 0.40D & Holladay 1: 0.48D; 0.37D). Similar trend was found in long eyes (Ophtha Top:0.58 D & IOLMaster using SRK/T:0.53D). Conclusions: Ophtha Top based on real ray-tracing method could provide predictable outcomes in all eyes, which was comparable to outcomes from IOLMaster 500 using SRK/T, Hoffer Q, Hollday 1 formula. Ophtha Top would be a promising alternative choice for IOL power calculation.
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Affiliation(s)
- Shasha Yu
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Nankai University Eye Hospital , Tianjin, China
| | - Cheng Zhe Lu
- Cataract Department, Tianjin Key Laboratory of Ophthalmology and Visual Science , Tianjin, China
| | - Yun Zhao
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Nankai University Eye Hospital , Tianjin, China
| | - Hui Song
- Cataract Department, Clinical College of Ophthalmology, Tianjin Medical University , Tianjin, China
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Chang PJ, Zhang F, Wang JJ, Zhao YE. Accuracy of Constant C for Ray Tracing: Assisted Intraocular Lens Power Calculation in Normal Ocular Axial Eyes. Ophthalmic Res 2020; 64:85-90. [PMID: 32305980 DOI: 10.1159/000507963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 04/17/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To evaluate the effect of constant C for ray tracing-assisted intraocular lens (IOL) power calculation in patients with different refractive power, we compared the refractive outcome of the ray tracing method based on constant C and conventional IOL calculation. METHODS 215 eyes which underwent phacoemulsification and IOL implantation were enrolled in the study. According to the average corneal power, patients were divided into 3 groups: high corneal power (K >45 D) group, medium corneal power (43 ≤ K ≤ 45 D) group, and low corneal power (K <43 D) group. The predicted sphero-equivalent refractive outcome for the IOL power implanted at surgery was calculated using the ray tracing method, SRK/T, and Haigis formulas. RESULTS On the basis of the corneal refractive power, there were 65 eyes of K >45 D (30.23%), 96 eyes of 43 ≤ K ≤ 45 D (44.65%), and 54 eyes of K <43 D (25.12%). In general, the ray tracing group had the smallest value of mean absolute error (MAE) and mean error, and the proportions of eyes with absolute error (AE) <0.50 and <0.75 D were significantly higher than those of the other 2 formulas (p = 0.010). In each group, the value of MAE was smallest in the ray tracing group; for the proportions of AEs <0.50 and <0.75 D, the values in the ray tracing group were higher than those in the SRK/T and Haigis groups. Especially in the high and low corneal refractive groups, the proportion of AE <0.25 D was also obviously higher, but only in the low corneal refractive power group, and the difference was statistically significant (p = 0.006). CONCLUSIONS Compared with the conventional formulas, C constant of the ray tracing-assisted IOL power calculation has more accuracy for the patients with different corneal refractive powers. Ray tracing could provide better guidance for IOL selection clinically.
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Affiliation(s)
- Ping-Jun Chang
- School of Optometry and Ophthalmology, Eye Hospital, Wenzhou Medical University, Wenzhou, China.,Key Laboratory of Vision Science, Ministry of Health PR China, Wenzhou, China
| | - Fan Zhang
- School of Optometry and Ophthalmology, Eye Hospital, Wenzhou Medical University, Wenzhou, China.,Key Laboratory of Vision Science, Ministry of Health PR China, Wenzhou, China
| | - Jia-Jun Wang
- School of Optometry and Ophthalmology, Eye Hospital, Wenzhou Medical University, Wenzhou, China.,Key Laboratory of Vision Science, Ministry of Health PR China, Wenzhou, China
| | - Yun-E Zhao
- School of Optometry and Ophthalmology, Eye Hospital, Wenzhou Medical University, Wenzhou, China, .,Key Laboratory of Vision Science, Ministry of Health PR China, Wenzhou, China,
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Development of a new intraocular lens power calculation method based on lens position estimated with optical coherence tomography. Sci Rep 2020; 10:6501. [PMID: 32300162 PMCID: PMC7162886 DOI: 10.1038/s41598-020-63546-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 04/01/2020] [Indexed: 12/02/2022] Open
Abstract
A new method is developed and validated for intraocular lens (IOL) power calculation based on paraxial ray tracing of the postoperative IOL positions, which are obtained with the use of anterior segment optical coherence tomography. Of the 474 eyes studied, 137 and 337 were grouped into training and validation sets, respectively. The positions of the implanted IOLs of the training datasets were characterized with multiple linear regression analyses one month after the operations. A new regression formula was developed to predict the postoperative anterior chamber depth with the use of the stepwise analysis results. In the validation dataset, postoperative refractive values were calculated according to the paraxial ray tracing of the cornea and lens based on the assumption of finite structural thicknesses with separate surface curvatures. The predicted refraction error was calculated as the difference of the expected postoperative refraction from the spherical-equivalent objective refraction values. The percentage error (within ±0.50 diopters) of the new formula was 84.3%. This was not significantly correlated to the axial length or keratometry. The developed formula yielded excellent postoperative refraction predictions and could be applicable to eyes with abnormal proportions, such as steep or flat corneal curvatures and short and long axial lengths.
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Luft N, Siedlecki J, Schworm B, Kreutzer TC, Mayer WJ, Priglinger SG, Dirisamer M. Intraocular Lens Power Calculation after Small Incision Lenticule Extraction. Sci Rep 2020; 10:5982. [PMID: 32249851 PMCID: PMC7136233 DOI: 10.1038/s41598-020-63118-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 03/14/2020] [Indexed: 11/09/2022] Open
Abstract
With more than 1.5 million Small Incision Lenticule Extraction (SMILE) procedures having already been performed worldwide in an ageing population, intraocular lens (IOL) power calculation in post-SMILE eyes will inevitably become a common challenge for ophthalmologists. Since no refractive outcomes of cataract surgery following SMILE have been published, there is a lack of empirical data for optimizing IOL power calculation. Using the ray tracing as the standard of reference - a purely physical method that obviates the need for any empirical optimization - we analyzed the agreement of various IOL power calculation formulas derived from the American Society of Cataract and Refractive Surgeons (ASCRS) post-keratorefractive surgery online calculator. In our study of 88 post-SMILE eyes, the Masket formula showed the smallest mean prediction error [-0.36 ± 0.32 diopters (D)] and median absolute error (0.33D) and yielded the largest percentage of eyes within ±0.50D (70%) in reference to ray tracing. Non-inferior refractive prediction errors and ±0.50D accuracies were achieved by the Barrett True K, Barrett True K No History and the Potvin-Hill formula. Use of these formulas in conjunction with ray tracing is recommended until sufficient data for empirical optimization of IOL power calculation after SMILE is available.
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Affiliation(s)
- Nikolaus Luft
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany. .,SMILE Eyes Clinic, Linz, Austria.
| | - Jakob Siedlecki
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany.,SMILE Eyes Clinic, Linz, Austria
| | - Benedikt Schworm
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany.,SMILE Eyes Clinic, Linz, Austria
| | - Thomas C Kreutzer
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Wolfgang J Mayer
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Siegfried G Priglinger
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany.,SMILE Eyes Clinic, Linz, Austria
| | - Martin Dirisamer
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany.,SMILE Eyes Clinic, Linz, Austria
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Zhou D, Sun Z, Deng G. Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia. Indian J Ophthalmol 2019; 67:484-489. [PMID: 30900579 PMCID: PMC6446621 DOI: 10.4103/ijo.ijo_937_18] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Purpose: Our study was conducted to evaluate and compare the accuracy of the refractive prediction determined by the calculation formulas for different intraocular lens (IOL) powers for high myopia. Methods: This study reviewed 217 eyes from 135 patients who had received cataract aspiration treatment and IOL implantation. The refractive mean numerical error (MNE) and mean absolute error (MAE) of the IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) were examined and compared. The MNE and MAE at different axial lengths (AL) were compared, and the percentage of every refractive error absolute value for each formula was calculated at ±0.25D, ±0.50D, ±1.00D, and ±2.00D. Results: In all, 98 patients were recruited into this study and 98 eyes of them were analyzed. We found that Barrett Universal II formula had the lowest MNE and MAE, SRK/T and Haigis formulas arrived at similar MNE and MAE, and the MNE and MAE calculated by Holladay and Hoffer Q formula were the highest. Barrett Universal II formulas have the lowest MAE among different AL patients, whereas it reached the highest percentage of refractive error absolute value within 0.5D in this study. The MAE of each formula is positively correlated with AL. Conclusion: Barrett Universal II formula rendered the lowest predictive error compared with SRK/T, Haigis, Holladay, and Hoffer Q formulas. Thus, Barrett Universal II formula may be regarded as a more reliable formula for high myopia.
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Affiliation(s)
- Dong Zhou
- Department of Ophthalmology, The Third People's Hospital of Changzhou, Changzhou, Jiangsu Province, China, India
| | - Zhuo Sun
- Department of Ophthalmology, The Third People's Hospital of Changzhou, Changzhou, Jiangsu Province, China, India
| | - Guohua Deng
- Department of Ophthalmology, The Third People's Hospital of Changzhou, Changzhou, Jiangsu Province, China, India
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Yagi-Yaguchi Y, Negishi K, Saiki M, Torii H, Tsubota K. Comparison of the Accuracy of Newer Intraocular Lens Power Calculation Methods in Eyes That Underwent Previous Phototherapeutic Keratectomy. J Refract Surg 2019; 35:310-316. [PMID: 31059580 DOI: 10.3928/1081597x-20190410-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 04/09/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the accuracy of intraocular lens (IOL) power calculations using ray tracing software in patients who had undergone phototherapeutic keratectomy (PTK). METHODS In this retrospective case series, 37 eyes of 22 patients (mean age: 69.4 years; range: 56 to 85 years) who underwent cataract surgery after PTK were reviewed. The prediction error, defined as the difference between the estimated postoperative spherical equivalent and the postoperative manifest refraction at the spectacle plane, was calculated using the following formulas: OKULIX (Tedics, Dortmund, Germany), PhacoOptics (IOL Innovations ApS, Aarhus, Denmark), Barrett True K No History (NH), and Camellin-Calossi. The PhacoOptics formula was used in three different ways: historical method (H), no history method (NH), and C-constant method (C). The median values of the arithmetic and absolute prediction errors among these six IOL calculation methods were compared. RESULTS The median arithmetic errors (in diopters [D]) and percentages of eyes within ±0.50 D of the absolute errors were as follows: OKULIX (0.33, range: -2.20 to 2.50, 30.6%), PhacoOptics (H) (-0.12, range: -3.28 to 4.85, 22.2%), PhacoOptics (NH) (-0.25, range: -2.08 to 1.70, 48.4%), PhacoOptics (C) (0.04, range: -1.40 to 2.18, 48.5%), Barrett True K (NH) (-0.35, range: -1.90 to 1.89, 48.6%), and Camellin-Calossi (-0.19, range: -1.78 to 1.47, 59.5%). CONCLUSIONS The PhacoOptics, especially the C-constant method (C), and Camellin-Calossi formulas were good options for calculating IOL powers in eyes that underwent PTK. [J Refract Surg. 2019;35(5):310-316.].
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