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Wagner FM, Hoffmann P, Preußner PR. Accuracy comparison of tomography devices for ray tracing-based intraocular lens calculation. J Cataract Refract Surg 2024; 50:110-115. [PMID: 37748039 DOI: 10.1097/j.jcrs.0000000000001320] [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: 12/04/2022] [Accepted: 09/17/2023] [Indexed: 09/27/2023]
Abstract
PURPOSE To evaluate the interchangeability of different tomography devices used for ray tracing-based intraocular lens (IOL) calculation. SETTING Eye clinic, Castrop-Rauxel, Germany. DESIGN Retrospective analysis. METHOD Measurements from 3 Placido-Scheimpflug devices and 3 optical coherence tomography (OCT) devices were compared in 83 and 161 other eyes after cataract surgery, respectively. 2-dimensional matrices of anterior local corneal curvature and local corneal thickness are transferred to the ray-tracing software OKULIX. Calculations are performed with the same IOL in the same position of an eye with the same axial length. Differences in spherical equivalent (SE), astigmatism, and spherical aberration are evaluated. Furthermore, the influence of the size of the matrices (optical zone) on the accuracy is quantified. RESULTS For the Placido-Scheimpflug devices, the deviations from the average of three measurements taken for each eye in SE (mean ± SD) were 0.17 ± 0.24 diopters (D), -0.26 ± 0.29 D, and 0.08 ± 0.39 D ( P < .001, analysis of variance [ANOVA]), for the centroids of the astigmatic differences 0.04 D/173 degrees, 0.14 D/93 degrees, and 0.10 D/7 degrees, and for the median of the absolute values of the vector differences 0.31 D, 0.33 D, and 0.29 D. For OCT devices, the corresponding results were 0.01 ± 0.21 D, -0.03 ± 0.21 D, and 0.02 ± 0.20 D ( P = .005, ANOVA); 0.18 D/120 degrees, 0.07 D/70 degrees, and 0.22 D/4 degrees; and 0.26 D, 0.30 D, and 0.33 D. The accuracy of the calculated spherical aberrations allows for an individual selection of the best fitting IOL model in most cases. CONCLUSIONS The differences are small enough to make the devices interchangeable regarding astigmatism and spherical aberration. Although there are significant differences in SE between Scheimpflug and OCT devices, the differences between OCT devices are also small enough to make them interchangeable, but the differences between Placido-Scheimpflug devices are too large to make these devices interchangeable.
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Affiliation(s)
- Felix M Wagner
- From the Department of Ophthalmology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (Wagner, Preußner); Augen- & Laserklinik Castrop Rauxel GmbH, Castrop-Rauxel, Germany (Hoffmann)
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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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Savage DE, Pantanelli SM. An update on intraocular lens power calculations in eyes with previous laser refractive surgery. Curr Opin Ophthalmol 2024; 35:34-43. [PMID: 37820078 DOI: 10.1097/icu.0000000000001004] [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: 10/13/2023]
Abstract
PURPOSE OF REVIEW There is an ever-growing body of research regarding intraocular lens (IOL) power calculations following photorefractive keratectomy (PRK), laser-assisted in-situ keratomileusis (LASIK), and small-incision lenticule extraction (SMILE). This review intends to summarize recent data and offer updated recommendations. RECENT FINDINGS Postmyopic LASIK/PRK eyes have the best refractive outcomes when multiple methods are averaged, or when Barrett True-K is used. Posthyperopic LASIK/PRK eyes also seem to do best when Barrett True-K is used, but with more variable results. With both aforementioned methods, using measured total corneal power incrementally improves results. For post-SMILE eyes, the first nontheoretical data favors raytracing. SUMMARY Refractive outcomes after cataract surgery in eyes with prior laser refractive surgery are less accurate and more variable compared to virgin eyes. Surgeons may simplify their approach to IOL power calculations in postmyopic and posthyperopic LASIK/PRK by using Barrett True-K, and employing measured total corneal power when available. For post-SMILE eyes, ray tracing seems to work well, but lack of accessibility may hamper its adoption.
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Affiliation(s)
- Daniel E Savage
- Department of Ophthalmology, David and Ilene Flaum Eye Institute
- Center for Visual Science, University of Rochester, Rochester, New York
| | - Seth M Pantanelli
- Department of Ophthalmology, Penn State College of Medicine, Hershey, Pennsylvania, USA
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Hammer A, Heeren TFC, Angunawela R, Marshall J, Saha K. A Novel Role for Corneal Pachymetry in Planning Cataract Surgery by Determining Changes in Spherical Equivalent Resulting from a Previous LASIK Treatment. J Ophthalmol 2023; 2023:2261831. [PMID: 37483313 PMCID: PMC10362985 DOI: 10.1155/2023/2261831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/22/2023] [Accepted: 04/27/2023] [Indexed: 07/25/2023] Open
Abstract
Objectives To provide a metric to differentiate between hyperopic and myopic ablation of a prior LASIK treatment based on the corneal pachymetry profile after laser vision correction (LVC). Methods Pachymetry data were retrospectively recovered from patients who had previous LASIK for refractive purposes between 2019 and 2020. Patients with any corneal disorder were excluded. Ablation spherical equivalent was predicted from the central to semiperipheral corneal thickness (CPT) ratio, both values were provided by using the Pentacam user interface software (UI), and values were computed from extracted raw pachymetry data. Results Data of 157 eyes of 81 patients were collected, of which data were analysed for 73 eyes of 73 patients to avoid concurrence of measurements in both eyes per subject (42% female; mean age 40.9; SD 12.8). The CPT ratio cutoff for distinction between myopic and hyperopic LASIK was 0.86 for Pentacam UI data. Sensitivity and specificity were 0.7 and 0.95, respectively. Accuracy increased with computation of the CPT ratio based on extracted raw data with sensitivity and specificity of 0.87 and 0.99, respectively. There was a marked linear correlation between the CPT ratio and the ablation spherical equivalent (R2 = 0.93). Conclusions CPT ratio cutoffs can correctly classify if a cornea previously had a hyperopic versus myopic LASIK surgery and estimate the ablation spherical equivalent of such treatment. This could prove useful for increased accuracy of intraocular lens (IOL) calculations for patients with no historical data of their prior LVC surgery at the time of cataract surgery planning.
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Affiliation(s)
- Arthur Hammer
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | | | - Romesh Angunawela
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- OCL Vision, London, UK
| | - John Marshall
- University College London, Institute of Ophthalmology, London, UK
| | - Kamran Saha
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
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Wendelstein J, Heath M, Riaz KM, Seiler T, Cooke DL, Langenbucher A, Hoffmann P, Kohnen T. Biometry and Intraocular Lens Power Calculation in Eyes with Prior Laser Vision Correction (LVC) - A Review. Klin Monbl Augenheilkd 2022; 239:971-981. [PMID: 35973684 DOI: 10.1055/a-1896-0881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
BACKGROUND An intraocular lens (IOL) calculation in eyes that have undergone laser vision correction (LVC) poses a significant clinical issue in regards to both patient expectation and accuracy. This review aims to describe the pitfalls of IOL power calculation after LVC and give an overview of the current methods of IOL power calculation after LVC. REVIEW Problems after LVC derive from the measurement of anterior corneal radii, central corneal thickness, asphericity, and the predicted effective lens position. A central issue is that most conventional 3rd generation formulas estimate lens position amongst other parameters on keratometry, which is altered in post-LVC eyes. CONCLUSION An IOL power calculation results in eyes with prior LVC that are notably impaired in eyes without prior surgery. Effective corneal power including anterior corneal curvature, posterior corneal curvature, CCT (central corneal thickness), and asphericity is essential. Total keratometry in combination with the Barrett True-K, EVO (emmetropia verifiying optical formula), or Haigis formula is relatively uncomplicated and seems to provide good results, as does the Barrett True-K formula with anterior K values. The ASCRS ( American Society of Cataract and Refractive Surgery) calculator combines results of various formulae and averages results, which allows a direct comparison between the different methods. Tomography-based raytracing and the Kane and the Castrop formulae need to be evaluated by future studies.
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Affiliation(s)
- Jascha Wendelstein
- IROC, Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland.,Abteilung für Augenheilkunde und Optometrie, Johannes Kepler Universität Linz, Linz, Austria.,Institut für Experimentelle Ophthalmologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Michael Heath
- College of Medicine, University of Oklahoma, Norman, Oklahoma, United States
| | - Kamran M Riaz
- University of Oklahoma, Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Theo Seiler
- IROC, Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland.,Universitätsklinik für Augenheilkunde, Inselspital, Bern, Switzerland.,Klinik für Augenheilkunde, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
| | - David L Cooke
- Great Lakes Eye Care, Saint Joseoph, United States.,Department of Neurology and Ophthalmology, Michigan State University, East Lansing, Michigan, United States
| | - Achim Langenbucher
- Institut für Experimentelle Ophthalmologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Peter Hoffmann
- Augen- und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany
| | - Thomas Kohnen
- Klinik für Augenheilkunde, Goethe-Universität, Frankfurt, Germany
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Srujana D, Shankar S, Bhanot R, Mohandas R, Srikanth S, Kumar A. Ray tracing biometry in post radial keratotomy eye. Eur J Ophthalmol 2022:11206721221102268. [PMID: 35570570 DOI: 10.1177/11206721221102268] [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: 11/16/2022]
Abstract
OBJECTIVE To report a case of post radial keratotomy (RK) cataract in a 55-year-old lady wherein biometry was done by ray-tracing method incorporated in scheimpflug topographer (Sirius + Scheimpflug Analyzer, CSO, Italy). METHOD In our case, we performed intraocular lens (IOL) power calculation using a recent concept of ray tracing with scheimpflug topographer and compared with traditional methods available at American Society of Cataract and Refractive Surgery(ASCRS) website (www.ascrs.org) for eyes with prior RK. Phacoemulsification was performed and a monofocal + 24.5D IOL implanted in the capsular bag. RESULT Manifest refraction at six weeks postoperative period was + 1.0DS/-2.0DC × 75° with spherical equivalence of 0. On comparison of all the methods used to calculate IOL power, the absolute errors of ray tracing and Barrett true K were found to be the least, 0.14 and 0.18 respectively. CONCLUSION Ray tracing biometry with scheimpflug topographer seems to provide accurate IOL power in post RK eyes.
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Affiliation(s)
- Dubbaka Srujana
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
| | - Sandeep Shankar
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
| | - Rohit Bhanot
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
| | - Renu Mohandas
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
| | - S Srikanth
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
| | - Ashok Kumar
- Department of Ophthalmology, 29590AFMC, Pune, Maharashtra, India
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IOL power calculation with ray tracing based on anterior segment OCT and adjusted axial length after myopic excimer laser surgery. J Cataract Refract Surg 2022; 48:947-953. [PMID: 35121684 DOI: 10.1097/j.jcrs.0000000000000902] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/27/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE To report the results of intraocular lens (IOL) power calculation by ray-tracing in eyes with previous myopic excimer laser surgery. SETTING G.B. Bietti Foundation I.R.C.C.S., Rome, Italy. DESIGN Retrospective interventional case series. METHODS A series of consecutive patients undergoing phacoemulsification and IOL implantation after myopic excimer laser was investigated. IOL power was calculated using ray-tracing software available on the anterior segment optical coherence tomographer MS-39 (CSO, Italy). Axial length (AL) was measured by optical biometry and 4 values were investigated: 1) that from the printout, 2) the modified Wang/Koch formula, 3) the polynomial equation for the Holladay 1 and 4) for the Holladay 2 formula. The mean prediction error (PE), median absolute error (MedAE), percentage of eyes with a PE within ±0.50 diopters (D) were reported. RESULTS We enrolled 39 eyes. Entering the original AL into ray-tracing led to a mean hyperopic PE (+0.56 ±0.54 D), whereas with the Wang/Koch formula a mean myopic PE (-0.41 ±0.53D) was obtained. The Holladay 1 and 2 polynomial equations lead to the lowest PEs (-0.10 ±0.49 and +0.08 ±0.49 D respectively), lowest MedAE (0.37 and 0.25 D) and highest percentages of eyes with a PE within ±0.50 D (71.79 and 76.92%). Calculations based on the Holladay 2 polynomial equation showed a statistically significant difference compared to other methods used (including Barrett-True K formula), with the only exception of the Holladay 1 polynomial equation. CONCLUSIONS IOL power can be accurately calculated by ray-tracing with adjusted AL according to the Holladay 2 polynomial equation.
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Effect of Implantable Collamer Lens on Anterior Segment Measurement and Intraocular Lens Power Calculation Based on IOLMaster 700 and Sirius. J Ophthalmol 2022; 2021:8988479. [PMID: 34970453 PMCID: PMC8714341 DOI: 10.1155/2021/8988479] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 12/04/2021] [Indexed: 11/20/2022] Open
Abstract
Purpose To investigate the possible effect of an implantable collamer lens (ICL) on ocular biometrics and intraocular lens (IOL) power calculation. Methods Ocular measurements were taken preoperatively and at the two-month follow-up using IOLMaster 700 and Sirius in 85 eyes (43 patients) who had previously undergone ICL surgery. IOL power was calculated using either IOLMaster 700 (Barrett Universal II formula) or Sirius (ray-tracing). All data were compared using the paired t-test. Results The difference between preoperative and postoperative anterior chamber depth (ACD), lens thickness (LT), and keratometry on the steep axis (K2) measured by IOLMaster 700 was statistically significant (p < 0.001). In 11 of 85 eyes, IOLMaster misjudged the anterior surface of the ICL as that of the lens, leading to an error in ACD and LT. There were no significant differences between preoperative and postoperative axial length (AL) (p = 0.223), white to white (WTW) (p = 0.100), keratometry on flat axis (K1) (p = 0.117), or central corneal thickness (CCT) (p = 0.648), measured using IOLMaster. The difference in IOL power calculated using the Barrett II formula was significant (p = 0.013). Regression analysis showed that AL and K had the greatest influence on IOL calculation (p < 0.001), and ACD and LT had less influence (p = 0.002, p = 0.218, respectively). K1 and K2 were modified to exclude the influence of K2, and modified IOLs showed no difference between pre and postoperation (p = 0.372). Preoperative and postoperative ACD measured using Sirius were significantly different (p < 0.001); however, the IOL power calculated using ray-tracing technology showed no significant differences (p > 0.05). Conclusions The ocular biometric apparatus may misjudge the anterior surface of the lens, resulting in measurement errors of ACD and LT, which has little effect on the calculation of IOL power when using IOLMaster 700 (Barrett Universal II formula) and Sirius (ray-tracing).
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