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Shouchane-Blum K, Reitblat O, Dadon J, Bahar I, Sella R. Evaluating Changes in Apparent Chord Mu after Pharmacological Pupil Dilatation. Ophthalmic Res 2023; 66:921-927. [PMID: 37231882 DOI: 10.1159/000530905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023]
Abstract
INTRODUCTION Preoperative measurements of apparent chord mu length above 0.6 mm have been associated with higher risks for photic phenomena after cataract surgery with multifocal intraocular lenses (MFIOLs). METHODS This retrospective study evaluated patients scheduled for elective cataract surgery at a single tertiary medical center between 2021 and 2022. Pupil diameter and apparent chord mu length were analyzed for eyes with biometry measurements from IOLMaster 700 (Carl Zeiss Meditec, AG) under photopic light conditions, before and after pharmacological pupil dilatation. Exclusion criteria were visual acuity worse than 20/100, prior intraocular surgery, refractive surgery, iris-related procedures, or pupil abnormalities affecting dilatation. Apparent chord mu lengths before and after pupil dilatation were compared. In addition, multivariate linear regression analysis, using a stepwise method, was conducted to assess possible predictors of apparent chord values. RESULTS Included were 87 eyes of 87 patients. Mean chord mu length increased after pupillary dilatation from 0.32 ± 0.17 mm to 0.41 ± 0.17 mm for right eyes (p < 0.001) and from 0.29 ± 0.16 mm to 0.40 ± 0.22 mm for left eyes (p < 0.001). Seven eyes (8.0%) had an apparent chord mu of 0.6 mm and above pre-dilatation. Fourteen eyes (16.1%) with an apparent chord mu under 0.6 mm pre-dilatation had apparent chord mu of 0.6 mm or above post-dilatation. CONCLUSION Apparent chord mu length significantly increases after pharmacological pupillary dilatation. Pupil size and dilatation status should always be considered during patient selection for a planned MFIOL using apparent chord mu length as a reference marker.
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Affiliation(s)
- Karny Shouchane-Blum
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Rabin Medical Center, Petah-Tikva, Israel
| | - Olga Reitblat
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Rabin Medical Center, Petah-Tikva, Israel
| | - Judith Dadon
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Rabin Medical Center, Petah-Tikva, Israel
| | - Irit Bahar
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Rabin Medical Center, Petah-Tikva, Israel
| | - Ruti Sella
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Rabin Medical Center, Petah-Tikva, Israel
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Comparative study of refractive and visual quality after wavefront-optimized FS-LASIK for angle kappa adjustment in dominant and nondominant eyes. J Cataract Refract Surg 2023; 49:184-189. [PMID: 36026702 DOI: 10.1097/j.jcrs.0000000000001050] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 08/18/2022] [Indexed: 02/02/2023]
Abstract
PURPOSE To investigate the differences between dominant and nondominant eyes in femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) with 50% angle kappa compensation on diopter and visual quality. SETTING University hospital. DESIGN Retrospective clinical study. METHODS 109 patients (218 eyes, 100%) with myopia who underwent FS-LASIK were randomly selected. The preoperative pupil size, center position, and offset between the coaxially sighted corneal light reflex ( P-Dist ) of the patients was recorded. In preoperative and postoperative 6 months, an iTrace wavefront aberrometer was used to measure the corneal, internal optics, and total aberrations. RESULTS The 6 months postoperatively for corneal coma of the dominant eyes were 0.141 ± 0.055 μm and the nondominant eyes were 0.157 ± 0.033 μm, which was significantly greater than the dominant eyes ( P = .028). The postoperative corneal coma aberration changes were positively correlated with preoperative P-Dist , the dominant eyes ( r = 0.221, P = .023), and the nondominant eyes ( r = 0.251, P = .009). CONCLUSIONS Adjusting the angle kappa percentage in the nondominant eyes to be higher than that of the dominant eyes in individualized corneal refractive surgery may help find the ablation center closest to the visual axis.
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Reliability and agreement of apparent chord mu measurements between static and dynamic evaluations. J Cataract Refract Surg 2023; 49:21-28. [PMID: 36573762 DOI: 10.1097/j.jcrs.0000000000001036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 07/26/2022] [Indexed: 12/28/2022]
Abstract
PURPOSE To assess the repeatability and agreement of Cartesian coordinates and the length of apparent chord mu and pupil diameter measurements during static (Galilei G4) and dynamic (Topolyzer Vario) evaluations. SETTING IOBA-Eye Institute, Valladolid, Spain. DESIGN Case series. METHODS 3 consecutive measurements per scenario (Galilei G4 and Topolyzer Vario under low mesopic and photopic conditions) were performed by the same clinician. The intrasession repeatability was assessed using the within-subject SD (Sw), the precision, the coefficient of variation, and the intraclass correlation coefficient (ICC). The agreement was analyzed using repeated-measures analysis of variance and the Bland-Altman method. RESULTS Thirty-seven healthy participants were recruited. The Sw values for chord mu parameters and pupil diameter ranged from 0.01 to 0.03 and 0.08 to 0.21, respectively. The ICC was ≥0.89 for all parameters. Galilei G4 and Topolyzer Vario under low mesopic and photopic conditions provided significantly different measures of apparent chord mu length (0.23 ± 0.11 mm, 0.30 ± 0.10 mm, and 0.25 ± 0.11 mm, respectively, P ≤ .02), X-coordinate (-0.18 ± 0.12 mm, -0.27 ± 0.11 mm, and -0.21 ± 0.12 mm, respectively, P < .001), and pupil diameter (3.38 ± 0.50 mm, 6.29 ± 0.60 mm, and 3.04 ± 0.41 mm, respectively, P < .001). Y-coordinate values obtained by Galilei G4 and Topolyzer Vario under low mesopic conditions were significantly different (0.06 ± 0.13 mm vs 0.03 ± 0.11 mm, respectively, P = .02), in contrast to Galilei G4 and Topolyzer Vario under photopic conditions (0.05 ± 0.13 mm, P = .82) and both illumination conditions of Topolyzer Vario (P ≥ .23). CONCLUSIONS Galilei G4 and Topolyzer Vario provide consistent measurements of apparent chord mu Cartesian coordinates and length, as well as pupil diameter; however, the measurements are not interchangeable. Ophthalmic surgeons should consider these findings when planning customized intraocular lens implantation and refractive surgery procedures.
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Bang SP, Lyu J, Ng CJ, Yoon G. Visual Axis and Stiles-Crawford Effect Peak Show a Positional Correlation in Normal Eyes: A Cohort Study. Invest Ophthalmol Vis Sci 2022; 63:26. [PMID: 36306143 PMCID: PMC9624269 DOI: 10.1167/iovs.63.11.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/03/2022] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to locate the visual axis and evaluate its correlation with the Stiles-Crawford effect (SCE) peak. Methods Ten young, healthy individuals (20 eyes) were enrolled. An optical system was developed to locate the visual axis and measure SCE. To locate the visual axis, 2 small laser spots at 450 nm and 680 nm were co-aligned and delivered to the retina. The participants were asked to move a translatable pinhole until these spots were perceived to overlap each other. The same system assessed SCE at 680 nm using a bipartite, 2-channel (reference and test) Maxwellian-view optical system. The peak positions were estimated using a two-dimensional Gaussian fitting function and correlated with the visual axis positions. Results Both the visual axis (x = 0.24 ± 0.35 mm, y = -0.16 ± 0.34 mm) and the SCE peak (x = 0.27 ± 0.35 mm, y = -0.15 ± 0.31 mm) showed intersubject variability among the cohort. The SCE peak positions were highly correlated in both the horizontal and vertical meridians to the visual axes (R2 = 0.98 and 0.96 for the x and y coordinates, respectively). Nine of the 10 participants demonstrated mirror symmetry for the coordinates of the visual axis and the SCE peak between the eyes (R2 = 0.71 for the visual axis and 0.76 for the SCE peak). Conclusions The visual axis and SCE peak locations varied among the participants; however, they were highly correlated with each other for each individual. These findings suggest a potential mechanism underlying the foveal cone photoreceptor alignment.
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Affiliation(s)
- Seung Pil Bang
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Jiakai Lyu
- Institute of Optics, University of Rochester, Rochester, New York, USA
| | - Cherlyn J. Ng
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Geunyoung Yoon
- College of Optometry, University of Houston, Houston, Texas, USA
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Sun S, Liu Z, Wu Y, Sun X, Zhao S, Huang Y. Characteristics of Pupil Offset in Young Asian Adults With Mild-Moderate and High Myopia. Transl Vis Sci Technol 2022; 11:13. [PMID: 35696132 PMCID: PMC9202332 DOI: 10.1167/tvst.11.6.13] [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] [Indexed: 11/27/2022] Open
Abstract
Purpose The purpose of this study was to explore the characteristics of pupil offset in young Asian adults with myopia. Methods In total, 1200 eyes (600 young adults, 18–35 years old) were divided into mild-moderate and high groups according to equivalent spherical diopters (SEQ). The pupil offset and its X and Y components were compared between the groups. Linear correlation was analyzed among pupil offset, X and Y components, and SEQ. Multiple linear regression analysis was conducted for pupil offset and eye parameters. Results The mean age of all subjects was 22.5 ± 4.8 years. The mean magnitude of the pupil offset (0.18 ± 0.09 mm vs. 0.15 ± 0.08 mm) and Y component (0.12 ± 0.08 mm vs. 0.10 ± 0.07 mm) were larger in the high group than in the mild-moderate group (P < 0.05). The magnitude of pupil offset, X and Y components, and SEQ were positively correlated. The pupil center (PC) of the right eye in the mild-moderate group was mainly superotemporal to the corneal vertex and mainly superonasal for the left eye and both eyes in the high group. Multiple linear regression analysis revealed that the magnitude of pupil offset correlated with central corneal thickness, intraocular pressure, and mean corneal curvature (P < 0.05). Conclusions The magnitude of the pupil offset that correlated with partial eye parameters and its X and Y components increased as the SEQ increased, and the PC gradually shifted toward the superonasal direction in young Asian adults with myopia. Translational Relevance Subjects with high myopia with a larger pupil offset should be considered for better postoperative visual quality during refractive surgery.
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Affiliation(s)
- Shengshu Sun
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China
| | - Zhanglin Liu
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China
| | - Yuan Wu
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China
| | - Xiaowen Sun
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China.,Department of Ophthalmology, People's Hospital of Rizhao, Rizhao, Shandong, China
| | - Shaozhen Zhao
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China
| | - Yue Huang
- Tianjin Medical University Eye Hospital, College of Optometry, Institute of Ophthalmology, National Clinical Medical Research Center for Eye, Ear, Nose and Throat Diseases, Tianjin Branch, Tianjin Key Laboratory of Retinal Function and Diseases, Tianjin, China
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Langenbucher A, Szentmáry N, Cayless A, Weisensee J, Wendelstein J, Hoffmann P. Prediction of CW chord as a measure for the eye's orientation axis after cataract surgery from preoperative IOLMaster 700 measurement data. Acta Ophthalmol 2021; 100:e1232-e1239. [PMID: 34850585 DOI: 10.1111/aos.15071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/28/2021] [Accepted: 11/19/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND The angles alpha and kappa are widely discussed for centring refractive procedures, but they cannot be determined with ophthalmic instruments. The purpose of this study is to investigate the Chang-Waring chord (position of the Purkinje reflex PI relative to the corneal centre) derived from an optical biometer before and after cataract surgery and to study the changes resulting from cataract surgery. METHODS The analysis was based on a large dataset of 1587 complete sets of preoperative and postoperative IOMaster 700 biometry measurements from two clinical centres, each containing: valid data for pupil and corneal centre position, the position of the Purkinje reflex PI originated from a coaxial fixation target, keratometry (K), axial length (AL), anterior chamber depth (ACD), lens thickness (LT), central corneal thickness CCT, and horizontal corneal diameter W2W. The Chang-Waring chord CW was derived from pupil centre and Purkinje reflex PI analysed preoperatively and postoperatively, and a multilinear regression model together with a feedforward neural network algorithm was set up to predict postoperative CW chord from preoperative CW chord, K and biometric distances of the eye. RESULTS The Y component of CW chord shows a slight shift in the inferior direction in both left and right eyes, before and after cataract surgery. The X component shows some shift in the temporal direction, which is more pronounced preoperatively and slightly reduced postoperatively but with a larger variation. The change in CW chord from preoperative to postoperative shows a slight shift in the superior and nasal directions. Our algorithms for prediction of postoperative CW chord using preoperative CW chord, keratometry and biometry as input data performed with a multilinear regression and a feedforward neural network approach were able to reduce the variance, but could not properly predict the postoperative CW chord X and Y components. CONCLUSION The CW chord as the position of the Purkinje reflex PI with respect to the pupil centre can be directly measured with any biometer, topographer or tomographer with a coaxial fixation light. The mean Y component does not differ between right and left eyes or preoperatively and postoperatively, but the mean temporal shift of the X component preoperatively is slightly reduced postoperatively, but with a larger scatter of the values.
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Affiliation(s)
- Achim Langenbucher
- Department of Experimental Ophthalmology Saarland University Homburg/Saar Germany
| | - Nóra Szentmáry
- Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Aniridia Research Saarland University Homburg/Saar Germany
- Department of Ophthalmology Semmelweis‐University Budapest Hungary
| | - Alan Cayless
- School of Physical Sciences The Open University Milton Keynes UK
| | - Johannes Weisensee
- Department of Experimental Ophthalmology Saarland University Homburg/Saar Germany
| | - Jascha Wendelstein
- Department of Ophthalmology Johannes Kepler University Linz Linz Austria
| | - Peter Hoffmann
- Augen‐ und Laserklinik Castrop‐Rauxel Castrop‐Rauxel Germany
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Rabina G, Mimouni M, Slomovic J, Sorkin N, Nemet A, Kaiserman I. Centration of myopic refractive ablation: should we center treatment on the pupil or the visual axis? Lasers Med Sci 2021; 36:1733-1739. [PMID: 34185167 DOI: 10.1007/s10103-021-03358-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/07/2021] [Indexed: 11/30/2022]
Abstract
The purpose of this study is to compare pupil versus corneal vertex-centered ablation for myopic laser refractive surgery. This study is a retrospective case series of right eyes of consecutive myopic patients undergoing either photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) with pupil or corneal vertex-centered ablation from January 2018 to April 2018. Overall 258 eyes of 258 patients were included. Of the 104 that underwent LASIK, 52 were treated centered on the corneal vertex (50%), and of the 154 that underwent PRK, 77 were treated centered on the corneal vertex (50%). There were no significant differences in baseline age, gender, spherical equivalence, sphere, cylinder, or angle kappa between both groups in either LASIK or PRK. There were no significant differences between the corneal vertex-centered and pupil-centered groups in terms of efficacy index (LASIK: 1.02 ± 0.14 vs 1.01 ± 0.13, p = 0.86; PRK: 1.00 ± 0.13 vs 0.99 ± 0.15, p = 0.61), safety index (LASIK: 1.02 ± 0.12 vs 1.01 ± 0.13, p = 0.70; PRK:1.02 ± 0.12 vs 1.02 ± 0.09, p = 0.97), and residual astigmatism (LASIK: 0.26 ± 0.25 vs 0.23 ± 0.28, p = 0.65; PRK:0.37 ± 0.41 vs 0.39 ± 0.31, p = 0.78). In mixed effect models, there were no significant differences between the corneal vertex-centered and pupil-centered groups when accounting for angle kappa (p > 0.05). Patients with large angle kappa (> 300 μm) eyes yielded similar results (p > 0.05). For conclusion, in myopic refractive surgery, performing ablation centered on the corneal vertex or on the pupil leads to similar outcomes regardless of the amount of angle kappa.
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Affiliation(s)
- Gilad Rabina
- Department of Ophthalmology, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, 64239, Tel-Aviv, Israel. .,Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
| | - Michael Mimouni
- Department of Ophthalmology, Rambam Health Care Campus, Haifa, Israel.,Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.,Care-Vision Laser Centers, Tel-Aviv, Israel
| | - Jacqueline Slomovic
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Nir Sorkin
- Department of Ophthalmology, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, 64239, Tel-Aviv, Israel.,Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Achia Nemet
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Igor Kaiserman
- Care-Vision Laser Centers, Tel-Aviv, Israel.,Department of Ophthalmology, Barzilai Medical Center, Ashkelon, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, Israel
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Comparison of effective corneal refractive centration to the visual axis: LASIK vs. SMILE, a contralateral eye digitized comparison of the postoperative result. J Cataract Refract Surg 2021; 47:1511-1518. [PMID: 34074993 DOI: 10.1097/j.jcrs.0000000000000687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 04/24/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE To define and compare the centration of the ablation effect in LASIK to the corresponding effect in SMILE, in myopic laser vision correction in order to possibly explain the refractive performance differences noted between the two procedures in a contralateral eye study. SETTING Private Ambulatory Eye Surgery Unit. DESIGN Prospective randomized contralateral eye study. METHODS In 22 consecutive patients (44 eyes), one eye was prospectively randomized to have myopic topography-guided LASIK treatment and the contralateral eye to have SMILE; Digital image analysis of the achieved centration to the aimed corneal vertex was assessed for both procedures on the perioperative Scheimpflug tangential curvature maps, using a proprietary digitized methodology. RESULTS The radial displacement between the attempted centration on the corneal vertex versus the center of the effective anterior corneal curvature flattening was on average 130 ± 62 μm in the LASIK group and 313 ± 144μm in the SMILE group (P<0.001). CONCLUSIONS In this contralateral eye study, topography-guided myopic LASIK was found to achieve significantly better effective centration compared to myopic SMILE, in regards digitally measured decentration of the effective refractive change achieved in the anterior corneal curvature from the corneal vertex. This may explain the previously reported superior visual outcomes in the LASIK group eyes when compared to the contralateral SMILE group eyes.
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Correlation Analysis of Refractive and Visual Quality after Wavefront-Optimized Laser In Situ Keratomileusis for 50% and 100% Angle Kappa Compensation. J Ophthalmol 2020; 2020:9873504. [PMID: 33083053 PMCID: PMC7556047 DOI: 10.1155/2020/9873504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/13/2020] [Accepted: 09/20/2020] [Indexed: 11/30/2022] Open
Abstract
Purpose To analyze the distribution of the offset between the pupil center and the coaxially sighted corneal light reflex (P-Dist), the effects of 50% and 100% angle kappa adjustments on refractive and visual quality in patients with moderate myopia were investigated. Methods A randomly selected 254 patients (254 eyes) with moderate myopia who underwent femtosecond laser-combined LASIK were examined. During the operation, the P-Dist of the patients was recorded by the x- and y-axis eyeball-tracking adjustment program of the WaveLight Eagle Vision EX500 excimer laser system. Preoperatively and 3 months postoperatively, the WaveLight® ALLEGRO Topolyzer was used to measure the pupil size and center position, and the wavefront sensor was used to measure the wavefront aberrations. The visual function tester (OPTEC 6500) measured contrast sensitivity. Results The average P-Dist was 0.220 ± 0.102 mm. When the P-Dist >0.220 mm, the postoperative residual cylinder was 0.29 ± 0.34 D in the group with the 50% adjustment and 0.40 ± 0.32 D in the 100% group, which was significantly higher than the 50% group (P=0.036). The coma was 0.21 ± 0.17 μm in the 50% adjusted group and 0.34 ± 0.25 μm in the 100% group, which was significantly higher than that in the 50% group (P=0.021). At the 1.5 c/d spatial frequency, contrast sensitivity in the adjusted 100% group was significantly lower than that in the 50% group under visual glare conditions (P=0.039). Conclusion The postoperative visual acuity and spherical equivalent were not affected in the two groups. However, when P-Dist >0.220 mm, the residual astigmatism and coma were lower in the 50% group. Individualized operations for those with moderate myopia and large-angle kappa in which 100% adjustment is chosen may not result in a better visual quality effect than 50%.
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Clinical outcomes of corneal refractive surgery comparing centration on the corneal vertex with the pupil center: a meta-analysis. Int Ophthalmol 2020; 40:3555-3563. [PMID: 32671600 DOI: 10.1007/s10792-020-01506-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 07/06/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE To compare the visual and refractive outcomes between centration on the corneal vertex and the pupil center in corneal refractive surgery. METHODS A comprehensive literature search was conducted using PubMed, MEDLINE, EMBASE, and the Cochrane Library to identify relevant studies. The primary outcomes were the postoperative spherical equivalent (SE), effectiveness [uncorrected distance visual acuity (UDVA) ≥ 20/20, eyes within ± 0.50 diopter (D) of target refraction], and safety [loss ≥ 2 lines of corrected distance visual acuity (CDVA)]. Higher-order aberrations were considered secondary outcomes. RESULTS Seven studies describing a total of 1964 eyes were included in this meta-analysis. A statistical significance in postoperative SE was found between the two centration methods for the correction of myopia that favor the CV-centered method (p < 0.001). No significant differences were observed in the proportion of eyes with UDVA ≥ 20/20 or loss ≥ 2 lines of CDVA postoperatively. However, the proportion of eyes within ± 0.50 D was slightly higher (p = 0.02) and the coma aberration was much lower in the corneal vertex-centered method (p < 0.001). CONCLUSION Preferable visual and refractive outcomes could be achieved with either centering on the corneal vertex or pupil center in corneal refractive surgery; however, the corneal vertex-centered method has shown partial benefits in some clinical indices. In order to obtain higher quality of clinical evidences, more randomized controlled trials (RCTs) are required in further investigations.
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Lower- and higher-order aberrations after photorefractive keratectomy with and without compensation of pupil centroid shift: fellow eye comparison. J Cataract Refract Surg 2020; 46:267-275. [PMID: 32126041 DOI: 10.1097/j.jcrs.0000000000000010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To study the effect of pupil centroid shift (PCS) compensation on lower- and higher-order aberrations (HOAs) after photorefractive keratectomy (PRK). SETTING Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. DESIGN Prospective intrasubject fellow eye study. METHODS One hundred twelve eyes of 56 patients with simple myopia or myopic astigmatism scheduled for PRK were enrolled. Preoperatively, the amount of PCS was measured in the horizontal and vertical directions. All eyes received wavefront-optimized treatment with static cyclotorsion compensation. PCS compensation was turned on for the right eye of each subject (PCS-on group), and turned off for the left eye (PCS-off group). Postoperatively, refraction and corneal HOAs were compared between the study groups at 6 months. RESULTS Mean preoperative myopia was -3.84 diopters (D) ± 2.41 (SD) vs -3.75 ± 2.27 D (P = .408), whereas mean preoperative cylinder was -1.18 D ± 1.15 (SD) vs -1.14 ± 1.16 D (P = .769) in the PCS-on and PCS-off groups, respectively. Mean absolute PCS values were 62.25 μm ± 41.82 (SD) vs 55.92 ± 37.47 μm (P = .45) in the horizontal direction and 65.04 ± 47.16 μm vs 58.40 ± 45.44 μm in the vertical direction (P = .29) in the PCS-on and PCS-off groups, respectively. The study groups were comparable in terms of postoperative refraction and root mean square of total corneal HOAs. CONCLUSIONS Compensation of PCS did not affect lower- and higher-order aberrations after wavefront-optimized PRK with static cyclotorsion compensation in myopic or myopic astigmatic eyes.
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The Effect of Intraoperative Angle Kappa Adjustment on Higher-Order Aberrations Before and After Small Incision Lenticule Extraction. Cornea 2020; 39:609-614. [PMID: 32040010 DOI: 10.1097/ico.0000000000002274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare higher-order aberrations (HOAs) after small incision lenticule extraction (SMILE) in patients with and without intraoperative angle kappa adjustments. METHODS This is a retrospective case series. One hundred six eyes of 106 patients who underwent SMILE at Tianjin Eye Hospital (Tianjin Medical University, Tianjin, China) for correction of myopia and myopic astigmatism were divided into 2 groups. The first group consisted of eyes with intraoperative angle kappa adjustment and the second group consisted of eyes without adjustment. Preoperative and postoperative visual outcome, refraction, and HOA measurements at 1 and 3 months were compared. RESULTS At the pupil size of 6 mm, vertical coma at 1 and 3 months after SMILE for the angle kappa-adjusted group was 0.153 ± 0.107 and 0.157 ± 0.094 μm, which were significantly lower than those of the nonadjusted group (0.204 ± 0.117 and 0.203 ± 0.113 μm, respectively) (P = 0.026 at 1 mo, P = 0.047 at 3 mo). The change in vertical coma between preoperative and postoperative measurements was 0.011 ± 0.136 and 0.023 ± 0.129 μm at 1 and 3 months postoperatively for the angle kappa-adjusted group, which were lower than those of the nonadjusted group (0.082 ± 0.165 and 0.085 ± 0.150 μm, respectively) (P = 0.023 at 1 mo, P = 0.045 at 3 mo). Subgroup analysis for eyes with large angle kappa demonstrated that the vertical coma was significantly less in the angle kappa-adjusted group at both 1 and 3 months (P = 0.009, P = 0.043, respectively). No significant correlation was observed between angle kappa and HOAs in the angle kappa-adjusted group. CONCLUSIONS Adjustment of angle kappa during SMILE resulted in less HOAs. It would provide more insight on how to optimize treatment centration in SMILE.
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Corneal Topographic Astigmatism Based on Total Corneal Power Data (CorT Total): A Benchmark for Total Corneal Astigmatism. Cornea 2019; 39:431-436. [DOI: 10.1097/ico.0000000000002162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Damgaard IB, Ang M, Mahmoud AM, Farook M, Roberts CJ, Mehta JS. Functional Optical Zone and Centration Following SMILE and LASIK: A Prospective, Randomized, Contralateral Eye Study. J Refract Surg 2019; 35:230-237. [PMID: 30984980 DOI: 10.3928/1081597x-20190313-01] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/13/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare centration and functional optical zone (FOZ) after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (LASIK). METHODS In this prospective, randomized, single-masked, paired-eyed, clinical trial, 70 patients received SMILE in one eye and LASIK in the other eye for myopia and myopic astigmatism. FOZ was calculated using custom software on 3-month postoperative refractive power maps (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany). Programmed treatment area was defined as the total area of the programmed OZ plus the transition zone. Centration was evaluated by the linear distance between FOZ centroid and the pupil center and the corneal apex. RESULTS The average preoperative spherical equivalent (-5.38 ± 1.65 vs -5.45 ± 1.61 diopters [D]), postoperative spherical equivalent (0.05 ± 0.39 vs 0.06 ± 0.39 D), uncorrected distance visual acuity (0.01 ± 0.13 vs 0.00 ± 0.08 logMAR), and corrected distance visual acuity (-0.07 ± 0.10 vs -0.07 ± 0.10 logMAR) were comparable in SMILE- and LASIK-treated eyes of the 60 patients with complete datasets (P > .419). Postoperative increase in spherical aberration was lower in SMILE than in LASIK (0.08 ± 0.16 vs 0.17 ± 0.18 µm, P = .002). The FOZ area was significantly larger in SMILE than in LASIK (30.25 ± 3.60 vs 29.21 ± 3.72 mm2), despite the smaller programmed OZ diameter (6.48 ± 0.08 vs 6.52 ± 0.11 mm) and smaller programmed treatment area (33.87 ± 0.81 vs 46.30 ± 2.61 mm2, P < .037). Pupil centration (0.43 ± 0.21 vs 0.41 ± 0.22 mm) and apex centration (0.48 ± 0.24 vs 0.48 ± 0.22 mm) were comparable between SMILE and LASIK (P > .694). CONCLUSIONS SMILE created a larger FOZ than LASIK, despite the smaller programmed OZ. This may be due to a difference in the biomechanical response between the two procedures. Visual outcome and centration were comparable between SMILE and LASIK. [J Refract Surg. 2019;35(4):230-237.].
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Liu Y, Wang Y. Optical quality comparison between laser ablated myopic eyes with centration on coaxially sighted corneal light reflex and on entrance pupil center. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2019; 36:B103-B109. [PMID: 31044979 DOI: 10.1364/josaa.36.00b103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
This paper aims to compare the image quality between centration on the coaxially sighted corneal light reflex (CSCLR) and on the entrance pupil center (EPC). Myopic laser ablation was simulated on eye models, and the optical performances were compared. Centration on the EPC leads to higher wavefront aberrations and lower modulation transfer function. The two centration methods give nearly identical retinal images for angle kappa less than 5°. Because of less tissue removal, centration on the EPC is probably preferable for angle kappa less than 5°, but CSCLR centration may be preferable for angle kappa larger than 5°. The degree of tilt of the post-surgery anterior corneal surface explains the differences between the two methods.
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Lee H, Roberts CJ, Arba-Mosquera S, Kang DSY, Reinstein DZ, Kim TI. Relationship Between Decentration and Induced Corneal Higher-Order Aberrations Following Small-Incision Lenticule Extraction Procedure. Invest Ophthalmol Vis Sci 2019; 59:2316-2324. [PMID: 29847636 DOI: 10.1167/iovs.17-23451] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the amount of lenticule decentration following small-incision lenticule extraction (SMILE) by using the Keratron Scout tangential topography difference map, and the relationship between the magnitudes of total decentration and induced corneal higher-order aberrations (HOAs). Methods This retrospective observational case series study analyzed decentration values obtained from the Keratron Scout tangential topography difference map of 360 eyes (360 patients) that underwent SMILE. Root mean square total HOAs, third order coma aberration, fourth order spherical aberration, as well as individual coefficients for vertical and horizontal coma were measured preoperatively and 3-months postoperatively. Simple linear regression analysis and piecewise regression models were used to determine the relationship between the magnitudes of total decentration and induced corneal HOAs. Results The mean total decentration distance from the corneal vertex was 0.36 ± 0.22 mm (range, 0.02-1.27 mm). There were significant differences in total HOAs, coma, vertical and horizontal comas, and spherical aberration between preoperative and 3-month postoperative assessments. Significant relationships between the magnitudes of total decentration and induced corneal HOAs were noted. Subgroup analysis according to the degree of total decentration (group I, total decentered displacement ≤0.335 mm; and group II, total decentered displacement >0.335 mm) revealed that induced changes in total HOAs, coma, vertical coma, and spherical aberration were significantly larger in group II than in group I. Conclusions A minimal degree of decentration was closely related to a smaller induction of corneal HOAs. Efforts to optimize centration are critical for achieving better surgical outcomes in SMILE.
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Affiliation(s)
- Hun Lee
- Department of Ophthalmology, International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, South Korea.,The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
| | - Cynthia J Roberts
- Department of Ophthalmology & Visual Science and Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
| | | | | | - Dan Z Reinstein
- London Vision Clinic, London, United Kingdom.,Department of Ophthalmology, Columbia University Medical Center, New York, New York, United States.,Centre Hospitalier National d'Ophtalmologie, Paris, France
| | - Tae-Im Kim
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
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Kim WK, Ryu IH, Kim JS, Jeon GH, Lee IS, Kim HS, Kim JK. Clinical Outcomes of One Day Small-incision Lenticule Extraction Compared with Scheduled Methods for Myopic Patients. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2019. [DOI: 10.3341/jkos.2019.60.3.223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Efficacy and safety of transepithelial photorefractive keratectomy. J Cataract Refract Surg 2018; 44:1267-1279. [PMID: 30172569 DOI: 10.1016/j.jcrs.2018.07.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 07/03/2018] [Accepted: 07/11/2018] [Indexed: 11/21/2022]
Abstract
Transepithelial photorefractive keratectomy (PRK) was introduced to prevent complications from conventional PRK and femtosecond laser-assisted laser in situ keratomileusis (LASIK). In the 2-step platform, phototherapeutic keratectomy is followed by PRK. It did not show notable safety or efficacy superiorities over conventional PRK. In the conventional single-step transepithelial PRK, ablation of epithelium and stroma occurs in a single continuous session by an Amaris laser. It showed better comparative safety results. Reverse single-step transepithelial PRK and the platform using smart-pulse technology were recent improvements in the single-step Amaris laser. They provide a smoother postablative stromal bed counter. In the refined single-step platform, a modified nomogram is used for determination of ablation parameters, along with modifications in postablative measures. It yielded better comparative results in hyperopia. Controlled trials comparing reverse, smart-pulse technology-equipped, or refined platforms of single-step transepithelial PRK with other modern laser-assisted methods could provide more robust evidence on the topic. Some key elements with significant roles in post-transepithelial PRK outcomes are discussed.
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Sun MS, Zhang L, Guo N, Song YZ, Zhang FJ. Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser. Int J Ophthalmol 2018; 11:662-667. [PMID: 29675388 DOI: 10.18240/ijo.2018.04.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 01/18/2018] [Indexed: 11/23/2022] Open
Abstract
AIM To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. METHODS Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. RESULTS Horizontally, synclastic adjustment between manually actual values (dxmanu) and Oculyzer topography guided data (dxocu) accounts 35.5% in study group, with mean dxmanu/dxocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dxauto) and Oculyzer topography data (dxocu) accounts 54.2%, with mean dxauto/dxocu of 0.79±0.66. Vertically, synclastic adjustment between dymanu and dyocu accounts 55.2% in study group, with mean dymanu/dyocu of 0.61±0.42; while in control group, synclastic adjustment between dyauto and dyocu accounts 66.1%, with mean dyauto/dyocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups (P=0.951, 0.621). CONCLUSION There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.
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Affiliation(s)
- Ming-Shen Sun
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China
| | - Li Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China
| | - Ning Guo
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China
| | - Yan-Zheng Song
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China
| | - Feng-Ju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China
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Abstract
OBJECTIVES To investigate the shifting of the line of sight (LoS) and the refractive, topographic, and aberrometric parameters that may be associated with the shifting of the LoS in eyes with tilted disk syndrome (TDS). METHODS Eighty left eyes of 80 subjects with TDS (Study Group) and 70 left eyes of 70 subjects with myopia and astigmatism (Control Group) were included in this study. Line-of-sight coordinates on the horizontal (x) and vertical (y) axes, refractive, topographic, and aberrometric parameters were evaluated. All parameters were compared between groups, and correlations were analyzed for the study group. RESULTS In the study group, the LoS significantly shifted to the superotemporal direction compared with the control group (P=0.022 and P=0.008 respectively). The shift on y-axis was correlated with mean cylindrical refractive error (r=-0.283, P=0.011), total root mean square (RMS) (r=0.321, P=0.004), higher-order aberration RMS (r=0.300, P=0.007), vertical coma (r=0.430, P<0.001), and vertical trefoil values (r=-0.455, P<0.001). CONCLUSIONS Results demonstrated a superotemporal shifting of the LoS in eyes with TDS. As eyes with TDS have an important place among candidates for refractive and multifocal intraocular lens implantation surgeries, this shift must be accounted for to prevent decentralization and provide satisfactory outcomes.
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Amigó A, Bonaque-González S, Guerras-Valera E. Control of Induced Spherical Aberration in Moderate Hyperopic LASIK by Customizing Corneal Asphericity. J Refract Surg 2016; 31:802-6. [PMID: 26653724 DOI: 10.3928/1081597x-20151111-03] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/28/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare differences in induced aberrations and visual acuity after wavefront-optimized LASIK and aspheric-customized LASIK for the treatment of hyperopia. METHODS Forty consecutive eyes underwent uneventful LASIK for treatment of moderate hyperopia (+3.82 ± 0.63 diopters [D] [+2.75; +5.125]). A standard procedure was performed in the wavefront-optimized LASIK group (n = 24), whereas a postoperative Q-factor equal to zero was scheduled in the aspheric-customized LASIK group (n = 16). RESULTS At 6 months, mean spherical aberration for a 6-mm pupil diameter was -0.39 ± 0.23 µm (range: -0.76 to 0.01 µm) and Q-factor was -0.52 ± 0.22 (range: -1.00 to -0.12 µm) in the wavefront-optimized group and 0.04 ± 0.18 µm (range: -0.34 to 0.29 µm) and -0.04 ± 0.25 (range: -0.64 to 0.40 µm) in the aspheric-customized LASIK group (P ≤ .05). All remaining outcomes showed no significant differences between groups. UDVA was 20/18.69 ± 0.15 (range: 0.80 to 1.20) in the wavefront-optimized LASIK group and 20/20 ± 0.17 (range: 0.50 to 1.20) in the aspheric-customized LASIK group. One patient in the wavefront-optimized LASIK group lost two or more lines of CDVA and no lines were lost in the aspheric-customized LASIK group. CONCLUSIONS The results in this small cases series suggest that using an aspheric-customized ablation profile with a target Q-factor equal to 0 in moderate hyperopic LASIK is statistically compatible with a diminishing induced spherical aberration without altering procedural safety when the WaveLight Allegretto 400-Hz excimer laser platform (Alcon Laboratories, Inc., Fort Worth, TX) is used.
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Chang JS, Law AK, Ng JC, Chan VK. Comparison of refractive and visual outcomes with centration points 80% and 100% from pupil center toward the coaxially sighted corneal light reflex. J Cataract Refract Surg 2016; 42:412-9. [DOI: 10.1016/j.jcrs.2015.09.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 11/29/2022]
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Arba-Mosquera S, de Ortueta D. LASIK for Hyperopia Using an Aberration-Neutral Profile With an Asymmetric Offset Centration. J Refract Surg 2016; 32:78-83. [DOI: 10.3928/1081597x-20151119-04] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 11/03/2015] [Indexed: 11/20/2022]
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Arba Mosquera S, Verma S, McAlinden C. Centration axis in refractive surgery. EYE AND VISION 2015; 2:4. [PMID: 26605360 PMCID: PMC4655455 DOI: 10.1186/s40662-015-0014-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/10/2015] [Indexed: 11/10/2022]
Abstract
The human eye is an asymmetric optical system and the real cornea is not a rotationally symmetrical volume. Each optical element in the eye has its own optical and neural axes. Defining the optimum center for laser ablation is difficult with many available approaches. We explain the various centration approaches (based on these reference axes) in refractive surgery and review their clinical outcomes. The line-of-sight (LOS) (the line joining the entrance pupil center with the fixation point) is often the recommended reference axis for representing wavefront aberrations of the whole eye (derived from the definition of chief ray in geometrical optics); however pupil centration can be unstable and change with the pupil size. The corneal vertex (CV) represents a stable preferable morphologic reference which is the best approximate for alignment to the visual axis. However, the corneal light reflex can be considered as non-constant, but dependent on the direction of gaze of the eye with respect to the light source. A compromise between the pupil and CV centered ablations is seen in the form of an asymmetric offset where the manifest refraction is referenced to the CV while the higher order aberrations are referenced to the pupil center. There is a need for a flexible choice of centration in excimer laser systems to design customized and non-customized treatments optimally.
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Affiliation(s)
- Samuel Arba Mosquera
- SCHWIND eye-tech-solutions, Kleinostheim, Germany ; Recognized Research Group in Optical Diagnostic Techniques, University of Valladolid, Valladolid, Spain ; Department of Ophthalmology and Sciences of Vision, University of Oviedo, Oviedo, Spain
| | | | - Colm McAlinden
- Flinders University, Adelaide, South Australia Australia ; Wenzhou Medical University, Wenzhou, Zhejiang China
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Chang DH, Waring GO. The subject-fixated coaxially sighted corneal light reflex: a clinical marker for centration of refractive treatments and devices. Am J Ophthalmol 2014; 158:863-74. [PMID: 25127696 DOI: 10.1016/j.ajo.2014.06.028] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 06/23/2014] [Accepted: 06/23/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE To describe the inconsistencies in definition, application, and usage of the ocular reference axes (optical axis, visual axis, line of sight, pupillary axis, and topographic axis) and angles (angle kappa, lambda, and alpha) and to propose a precise, reproducible, clinically defined reference marker and axis for centration of refractive treatments and devices. DESIGN Perspective. METHODS Literature review of papers dealing with ocular reference axes, angles, and centration. RESULTS The inconsistent definitions and usage of the current ocular axes, as derived from eye models, limit their clinical utility. With a clear understanding of Purkinje images and a defined alignment of the observer, light source/fixation target, and subject eye, the subject-fixated coaxially sighted corneal light reflex can be a clinically useful reference marker. The axis formed by connecting the subject-fixated coaxially sighted corneal light reflex and the fixation point, the subject-fixated coaxially sighted corneal light reflex axis, is independent of pupillary dilation and phakic status of the eye. The relationship of the subject-fixated coaxially sighted corneal light reflex axis to a refined definition of the visual axis without reference to nodal points, the foveal-fixation axis, is discussed. The displacement between the subject-fixated coaxially sighted corneal light reflex and pupil center is described not by an angle, but by a chord, here termed chord mu. The application of the subject-fixated coaxially sighted corneal light reflex to the surgical centration of refractive treatments and devices is discussed. CONCLUSION As a clinically defined reference marker, the subject-fixated coaxially sighted corneal light reflex avoids the shortcomings of current ocular axes for clinical application and may contribute to better consensus in the literature and improved patient outcomes.
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Reinstein DZ, Gobbe M, Archer TJ. Coaxially sighted corneal light reflex versus entrance pupil center centration of moderate to high hyperopic corneal ablations in eyes with small and large angle kappa. J Refract Surg 2013; 29:518-25. [PMID: 23909778 DOI: 10.3928/1081597x-20130719-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 04/01/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To determine whether centering ablations on the coaxially sighted corneal light reflex (CSCLR) in eyes with large angle kappa leads to poor visual outcomes when compared to patients with eyes with negligible angle kappa that by default would be centered on the entrance pupil. In eyes with no angle kappa, the CSCLR coincides with the entrance pupil center, whereas eyes with large angle kappa possess an offset between the CSCLR and the entrance pupil center. METHODS This study was a retrospective case series of consecutive patients treated by hyperopic LASIK using the MEL80 excimer laser (Carl Zeiss Meditec, Jena, Germany). All ablations were centered on the CSCLR using the standard non-wavefront-guided ablation profile. Angle kappa was classified according to pupil offset defined as the distance in the corneal plane between the entrance pupil center and the corneal vertex. Eyes were divided into two discrete groups according to the pupil offset: small angle kappa for pupil offset of 0.25 mm or less (n = 30) and large angle kappa for pupil offset of 0.55 mm or greater (n = 30). Safety, accuracy, cylinder vector analysis, contrast sensitivity, vertex centered corneal aberrations, entrance pupil centered whole eye aberrometry, and night vision disturbances were compared between the two groups. RESULTS There were no statistically significant differences in safety, accuracy, induced astigmatism, contrast sensitivity, or night vision disturbances between the two groups. There was also no statistically significant difference between groups for vertex centered corneal aberrations; however, as expected, coma was higher in the large angle kappa group for entrance pupil centered aberrometry because the treatment had been centered on the CSCLR rather than the entrance pupil center. CONCLUSION Refractive outcomes of high hyperopic LASIK were not found to be worse for eyes where ablation was centered more than 0.55 mm from the entrance pupil as determined by CSCLR in eyes with large angle kappa. The absence of poor quality visual outcomes in cases, which by entrance pupil centration are considered significantly "decentered," supports the notion that centration relative to the CSCLR may be preferable. This provides evidence that refractive corneal ablation should not be systematically aligned with the entrance pupil center.
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Okamoto S, Kimura K, Funakura M, Ikeda N, Hiramatsu H, Bains HS. Comparison of wavefront-guided aspheric laser in situ keratomileusis for myopia: coaxially sighted corneal-light-reflex versus line-of-sight centration. J Cataract Refract Surg 2012; 37:1951-60. [PMID: 22018362 DOI: 10.1016/j.jcrs.2011.05.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 04/07/2011] [Accepted: 05/04/2011] [Indexed: 11/29/2022]
Abstract
PURPOSE To compare refractive outcomes, higher-order aberrations (HOAs), and contrast sensitivity of myopic wavefront-guided aspheric laser in situ keratomileusis centered on the coaxially sighted corneal light reflex or on the line of sight. SETTING Okamoto Eye Clinic, Ehime, Japan. DESIGN Comparative case series. METHODS Data at 3 months were compared based on the distance between the coaxially sighted corneal light reflex and the line of sight (P-distance) as follows: distance greater than 0.25 mm (high-distance group), distance greater than 0.15 mm and less than 0.25 mm (intermediate-distance group), and distance less than 0.15 mm (low distance group). RESULTS The chart review included 317 eyes in the corneal-light-reflex group and 269 eyes in the line-of-sight group. The mean postoperative manifest refraction spherical equivalent was +0.123 diopter (D) ± 0.378 (SD) and +0.187 ± 0.480 D, respectively (P = .07). The safety and efficacy indices were significantly higher in the corneal-light-reflex group, including the high-distance subgroup and eyes with a P-distance less than 0.25 mm (P<.05, all cases). The HOAs (P<.001) and coma (P = .001) were significantly higher in the line-of-sight group (P<.001 and P = .001, respectively). The line-of-sight group had a significantly greater change in contrast sensitivity (P = .026). CONCLUSIONS Centration on the coaxially sighted corneal light reflex resulted in better safety, effectiveness, and contrast sensitivity than line-of-sight centration. Centration on the coaxially sighted corneal light reflex was safer for myopic eyes with P-distances greater than 0.25 mm. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.
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Reinstein DZ, Archer TJ, Gobbe M. Is topography-guided ablation profile centered on the corneal vertex better than wavefront-guided ablation profile centered on the entrance pupil? J Refract Surg 2011; 28:139-43. [PMID: 22107064 DOI: 10.3928/1081597x-20111115-01] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 08/24/2011] [Indexed: 11/20/2022]
Abstract
PURPOSE To illustrate the hypothesis that corneal vertex centration is superior to entrance pupil centration when guiding an ablation by wavefront. METHODS In one case example of therapeutic retreatment for treatment zone decentration after primary radial keratotomy (RK) centered on the entrance pupil (line of sight), both a whole-eye wavefront-guided ablation profile (WASCA data) and a topography-guided ablation profile (Atlas data) were generated using the CRS-Master (Carl Zeiss Meditec) and compared. The patient had a large vertical angle kappa. Corneal topography demonstrated that the zone of flattening was decentered superiorly with reference to the corneal vertex and the patient reported severe night vision disturbances. RESULTS The wavefront-guided profile, centered on the line of sight, was symmetrical because the wavefront was dominated by spherical aberration induced by the primary RK treatment. On the other hand, the topography-guided profile, centered on the corneal vertex, was asymmetric with an inferior region of ablation, which would logically improve the topographic decentration. The topography-guided profile was chosen for photorefractive keratectomy using the MEL 80 excimer laser (Carl Zeiss). Ten months after the procedure, the treatment zone was topographically well centered on the corneal vertex. Whole-eye higher order root-mean-square (RMS) was reduced by 43% and corneal higher order RMS was reduced by 61%. The patient reported large subjective improvement in the quality of vision and marked reduction in night vision disturbances. CONCLUSIONS This case provides evidence that wavefront data centered on the entrance pupil center may not represent the patient's view and the treatment zone should preferably be centered on the corneal vertex rather than the entrance pupil center.
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