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Moshirfar M, Cha DS, Santos JM, Herron MS, Hoopes PC. Changes in Posterior Cornea and Posterior-To-Anterior Curvature Radii Ratio 1 year After LASIK, PRK, and SMILE Treatment of Myopia. Cornea 2024:00003226-990000000-00532. [PMID: 38561842 DOI: 10.1097/ico.0000000000003530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 02/04/2024] [Indexed: 04/04/2024]
Abstract
PURPOSE The purpose of this study was to compare changes in the posterior curvature and the posterior-anterior radii ratio of the cornea, 1 year postoperatively in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE). METHODS This retrospective study was performed at a single surgical center. 199 eyes were included in the study from 119 patients with manifest refraction spherical equivalents from -7.61 to -2.54 D. 67 eyes underwent LASIK, 89 underwent PRK, and 43 underwent SMILE. Both preoperative and 1-year postoperative front and back sagittal keratometry were measured at 4- to 6-mm zones around the corneal vertex. Corneal asphericity (Q-value) was measured at an 8-mm zone around the corneal vertex. RESULTS The average change in the posterior-anterior radii ratio after LASIK, PRK, and SMILE did not differ between surgery groups at 4 mm (LASIK: -0.075, PRK: -0.073, SMILE: -0.072, P = 0.720), 5 mm (LASIK: -0.072, PRK: -0.068, SMILE: -0.068, P = 0.531), or 6 mm (LASIK: -0.075, PRK: -0.071, SMILE: -0.072, P = 0.456) zones. Anterior Q-value significantly positively increased after all 3 surgeries (P < 0.001). The posterior Q-value also significantly positively increased after LASIK (P < 0.001) and SMILE (P < 0.001), but not after PRK (P = 0.227). Both anterior and posterior keratometric power decreased significantly after LASIK, PRK, and SMILE for all diameters. CONCLUSIONS The change in the posterior-anterior radii ratio was not influenced by the type of refractive surgery performed, as indicated by statistically identical preoperative, postoperative, and delta values. In addition, the posterior cornea exhibited paracentral flattening after LASIK, SMILE, and PRK and increased oblateness after LASIK and SMILE.
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Affiliation(s)
- Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT
- Utah Lions Eye Bank, Murray, UT
| | - David S Cha
- Saint Louis University School of Medicine, Saint Louis, MO
| | - Jordan M Santos
- University of Arizona College of Medicine Phoenix, Phoenix, AZ; and
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Ying J, Zhang J, Wang B, Pan F, Yang S. Comprehensive Assessment of Posterior Corneal Asphericity Change Calculated by Tangential Radius of Curvature After FS-LASIK and SMILE. J Refract Surg 2024; 40:e133-e141. [PMID: 38466766 DOI: 10.3928/1081597x-20240205-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
PURPOSE To evaluate changes in posterior corneal asphericity (ΔQ) using the tangential radius of curvature after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) procedures. METHODS One hundred twenty right eyes of myopic patients who underwent either FS-LASIK or SMILE procedures were analyzed using Sirius 3D corneal topography for assessment. The tangential radius was employed to calculate both preoperative and postoperative posterior corneal Q-values across each semimeridian. After both surgical interventions, the ΔQ value variations across the 360° semimeridional regions of the posterior corneal surface were compared. RESULTS A marked postoperative increase in the posterior corneal Q-value was documented. No significant differences were noted between the postoperative Q-values or ΔQ-values of the two surgical approaches. Among patients with moderate myopia, postoperative Q-value exhibited considerably lower increases and ΔQ-value significantly smaller than their counterparts with high myopia. Moreover, the fluctuation in ΔQ across semimeridional regions was less evident in patients with moderate myopia than in those with high myopia. Notably, the degree of ΔQ fluctuation across semimeridional regions was similar between both surgical categories. These data offer insights into variations in the posterior corneal surface after refractive surgeries depending on the degree of myopia, illuminating their clinical relevance. CONCLUSIONS Both FS-LASIK and SMILE introduce notable changes to posterior corneal asphericity among patients with different myopia intensities. Furthermore, the influence on the asphericity across the entire posterior surface is similarly distributed between FS-LASIK and SMILE techniques. [J Refract Surg. 2024;40(3):e133-e141.].
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Bouazizi H, Brunette I, Meunier J. Comparison of polynomial and rational function cornea models for effective dimensionality reduction. Comput Biol Med 2023; 167:107635. [PMID: 37952306 DOI: 10.1016/j.compbiomed.2023.107635] [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: 04/05/2023] [Revised: 09/24/2023] [Accepted: 10/23/2023] [Indexed: 11/14/2023]
Abstract
This study aims to examine geometric models of the corneal surface that can be used to reduce in reasonable time the dimensionality of datasets of normal anterior corneas. Polynomial models (P) like Zernike polynomials (ZP) and spherical harmonic polynomials (SHP) were obvious candidates along with their rational function (R) counterparts, namely Zernike rational functions (ZR) and spherical harmonic rational functions (SHR, new model). Knowing that both SHP and ZR were more accurate than ZP for the modeling of normal and keratoconus corneas, it was expected that both spherical harmonic (SH) models (SHP and SHR) would be more accurate than their Zernike (Z) counterparts (ZP and ZR, respectively), and both rational (R) models (SHR and ZR) more accurate than their polynomial counterparts (SHP and ZP, respectively) for a low dimensional space (coefficient number J < 30). This was the case. The SH factor contributed more to accuracy than the R factor. Considering the corneal processing time as a function of J, P models were processed in quasi-linear time with a quasi-null slope and rational models in polynomial time. Z models were faster than SH models, and increasingly so in their R version. In sum, for corneal dimensionality reduction, SHR is the most accurate model, but its processing time is increasingly prohibitive unless the best coefficient combination is identified beforehand. ZP is the fastest model and is reasonably accurate with normal corneas for exploratory tasks. SHP is the best compromise between accuracy and speed.
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Affiliation(s)
- Hala Bouazizi
- Department of Computer Science and Operations Research, University of Montreal, Montreal, Quebec, Canada.
| | - Isabelle Brunette
- Department of Ophthalmology, University of Montreal, Montreal, Quebec, Canada; Maisonneuve-Rosemont Hospital Research Center, Montreal, Quebec, Canada
| | - Jean Meunier
- Department of Computer Science and Operations Research, University of Montreal, Montreal, Quebec, Canada; Department of Ophthalmology, University of Montreal, Montreal, Quebec, Canada
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Gabric I, Bohac M, Gabric K, Arba Mosquera S. First European results of a new refractive lenticular extraction procedure-SmartSight by SCHWIND eye-tech-solutions. Eye (Lond) 2023; 37:3768-3775. [PMID: 37277614 PMCID: PMC10698070 DOI: 10.1038/s41433-023-02601-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 05/05/2023] [Accepted: 05/19/2023] [Indexed: 06/07/2023] Open
Abstract
BACKGROUND To evaluate vision 3 months after SmartSight lenticule extraction treatments. DESIGN Case series. METHODS This case series of patients were treated at Specialty Eye Hospital Svjetlost in Zagreb, Croatia. Sixty eyes of 31 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 33 ± 6 years (range 23-45 years) at the time of treatment with a mean spherical equivalent refraction of -5.10 ± 1.35 D and mean astigmatism of 0.46 ± 0.36 D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Ocular and corneal wavefront aberrations have been postoperatively compared to the preoperative baseline values. Changes in ocular wavefront refraction, as well as changes in keratometric readings are reported. RESULTS At 3 months post-operatively, mean UDVA was 20/20 ± 2. Spherical equivalent showed a low myopic residual refraction of -0.37 ± 0.58 D with refractive astigmatism of 0.46 ± 0.26 D postoperatively. There was a slight improvement of 0.1 Snellen lines at 3-months follow-up. Compared to the preoperative status, ocular aberrations (at 6 mm diameter) did not change at 3 months follow-up; whereas corneal aberrations increased (+0.22 ± 0.21 µm for coma; +0.17 ± 0.19 µm for spherical aberration; and +0.32 ± 0.26 µm for HOA-RMS). The same correction was determined using changes in ocular wavefront refraction, as well as changes in keratometric readings. CONCLUSION Lenticule extraction after SmartSight is safe and efficacious in the first 3 months postoperatively. The post-operative outcomes indicate improvements in vision.
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Affiliation(s)
- Ivan Gabric
- Specialty Eye Hospital Svjetlost, School of Medicine University of Rijeka, Zagreb, Croatia
| | - Maja Bohac
- Specialty Eye Hospital Svjetlost, School of Medicine University of Rijeka, Zagreb, Croatia.
| | - Kresimir Gabric
- Specialty Eye Hospital Svjetlost, School of Medicine University of Rijeka, Zagreb, Croatia
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Pedrotti E, Bonacci E, Fasolo A, Fraccaroli S, Anastasi M, Vinciguerra R, Vinciguerra P, Giorgio M. Meniscus-Shaped Stromal Lenticule Addition Keratoplasty for Corneal Regularization and Thickening in Advanced Keratoconus. Cornea 2023; 42:1221-1228. [PMID: 36156527 DOI: 10.1097/ico.0000000000003144] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/01/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of this study was to investigate the outcome of the meniscus-shaped stromal lenticule addition keratoplasty (MS-SLAK) in corneal regularization and thickness. METHODS Patients waiting for deep anterior lamellar keratoplasty for advanced keratoconus with an intolerance to contact lenses (CLs) underwent the MS-SLAK procedure by FSL 80 kHz ablation (VICTUS, Technolas Perfect Vision, DE). Customized positive meniscus-shaped stromal lenticules were obtained and implanted. Examination was performed at baseline and at 3-, 6-, and 12-month follow-up and included corrected distance visual acuity both with spectacles and CLs (spectacle CDVA and CL-CDVA), manifest refraction spherical equivalent, slit-lamp examination, anterior segment optical coherence tomography, corneal topography, and in vivo confocal microscopy. RESULTS Fifteen patients completed the study. Statistical increases in corneal thickness values were found from the first follow-up ( P < 0.001). Improvement in the Surface Asymmetry Index ( P = 0.04), Symmetry Index ( P = 0.02), spherical aberration ( P < 0.001), coma ( P = 0.18), high-order aberration ( P = 0.37), and anterior asphericity index (Q) ( P = 0.31) were found at 12 months. At the 12-month follow-up, no improvement were found in spectacle CDVA ( P = 0.23); however, all patients reported CL wearing tolerance recovery, and significant improvement in CL-CDVA ( P = 0.002) was found. The confocal microscopy at 12 months showed a significant increase in keratocyte density within the lenticule and absence of fibrotic reactions in both anterior and posterior interfaces. CONCLUSIONS MS-SLAK seems to be effective in regularizing the corneal surface as showed by the significant improvement in topographic symmetry indices, coma, and high-order aberration. The corneal regularization is also confirmed by the results in anterior Q and the recovery of the CL wearing tolerance.
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Affiliation(s)
- Emilio Pedrotti
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Erika Bonacci
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Adriano Fasolo
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Sebastiano Fraccaroli
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Marco Anastasi
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | | | - Paolo Vinciguerra
- IRCCS Humanitas Research Hospital, Milan, Italy; and
- Humanitas University, Department of Biomedical Sciences, Milan, Italy
| | - Marchini Giorgio
- Ophthalmic Unit, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Wei J, He R, Wang X, Song Y, Yao J, Liu X, Yang X, Chen W, Li X. The Corneal Ectasia Model of Rabbit: A Validity and Stability Study. Bioengineering (Basel) 2023; 10:bioengineering10040479. [PMID: 37106666 PMCID: PMC10135747 DOI: 10.3390/bioengineering10040479] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Keratoconus is a bilateral progressive degenerative corneal disease characterized by localized corneal thinning and dilatation. The pathogenesis of keratoconus is not fully elucidated. To gain a better understanding of the pathophysiology of this disease and to explore potential treatments, animal models are essential for basic research. Several attempts have been made to establish animal models of corneal ectasia by using collagenase. However, continuous changes of the cornea have not been well-tracked for the model. In this study, corneal morphology and biomechanical behavior in vivo were determined before and after collagenase Ⅱ treatment at 2, 4, and 8 weeks. The elastic modulus and histology of cornea tissues ex vivo were measured at 8 weeks postoperatively. The results showed that the posterior corneal curvature (Km B) increased and central corneal thickness (CCT) decreased after collagenase treatment. The mechanical properties of ectatic corneas weakened significantly and the collagen fiber interval in the stromal layer was increased and disorganized. This study provides insights into the changes of corneal morphology and biomechanical properties in a rabbit model of corneal ectasia. Changes observed at 8 weeks indicated that the cornea was still undergoing remodeling.
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Affiliation(s)
- Junchao Wei
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Rui He
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Xiaogang Wang
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Yaowen Song
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Jinhan Yao
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Xiaona Liu
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xin Yang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xiaona Li
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
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Wang X, Xia L. Evaluation of the Effects of Myopic Astigmatism Correction and Anterior Corneal Curvature on Functional Optical Zone After SMILE. J Refract Surg 2023; 39:135-141. [PMID: 36779466 DOI: 10.3928/1081597x-20221215-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
PURPOSE To evaluate the influence of different degrees of myopic astigmatism correction and preoperative anterior corneal curvature on the functional optical zone (FOZ) following small incision lenticule extraction (SMILE). METHODS In this retrospective study, 68 patients (106 eyes) treated with SMILE were grouped according to myopic astigmatism correction: control (0.00 diopters [D]), moderate astigmatism (-0.50 to -2.00 D), and high astigmatism (> -2.00 D). The FOZ was measured and compared between the three groups for 3 months. Correlations between attempted correction, anterior corneal curvature, corneal aberrations, and the FOZ were analyzed. RESULTS The preoperative mean treatment spherical equivalent was comparable among the three groups. The average FOZ was 5.06 ± 0.24 mm in the control group, 5.19 ± 0.25 mm in the moderate astigmatism group, and 5.35 ± 0.20 mm in the high astigmatism group The FOZ showed statistically significant differences among the three groups (P < .001), particularly between the high astigmatism group and the other two groups (P < .001 and .018). Correlation analysis showed that the total higher order aberrations, coma, and spherical aberration change were correlated with the FOZ (P < .001). Preoperative steep keratometry, average keratometry, and corneal astigmatism were significantly correlated with the FOZ (P < .05). The correlation remained after excluding the influence of attempted correction on the FOZ (P < .05). After adjusting for other risk factors using multiple linear regression analysis, there was still a significant positive association between preoperative steep keratometry and the FOZ (P < .001). CONCLUSIONS Patients with higher myopic astigmatism achieved a larger FOZ and less induced horizontal coma than the control and moderate astigmatism groups. A larger FOZ after SMILE can be achieved in eyes with steeper keratometry. [J Refract Surg. 2023;39(2):135-141.].
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Pradhan KR, Arba Mosquera S. Twelve-month outcomes of a new refractive lenticular extraction procedure. JOURNAL OF OPTOMETRY 2023; 16:30-41. [PMID: 34949535 PMCID: PMC9811368 DOI: 10.1016/j.optom.2021.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 11/02/2021] [Accepted: 11/11/2021] [Indexed: 06/07/2023]
Abstract
BACKGROUND To evaluate the 12-month refractive and visual outcomes of Small Incision Guided Human-cornea Treatment (SmartSight®, SCHWIND eye-tech-solutions, Kleinostheim, Germany) in the treatment of myopia corrections with low to moderate astigmatism with the use of a new femtosecond laser system. METHODS 221 eyes of 114 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 28±6 years at the time of treatment with a mean spherical equivalent refraction of -6.26±2.17D and mean astigmatism of 0.92±0.68D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Refractive changes have been determined in terms of changes in refraction, as well as changes in keratometric readings. The changes in central epithelial thickness have been determined. RESULTS At twelve months post-operatively, mean UDVA was 20/21±2. Spherical equivalent showed a residual refraction of +0.48±0.31D with refractive astigmatism of 0.13±0.18D postoperatively. There was a slight decrease of -0.1 Snellen lines at 12-months follow-up. The same correction was determined using changes in refraction, as well as changes in keratometric readings. The central epithelial thickness increased by +3±2µm. Spherical equivalent correction within ±0.50D was achieved in 199 eyes (90%), and cylindrical correction in 221 (100%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 213 eyes (96%), and postoperative uncorrected (UDVA) was 20/20 or better in 205 eyes (93%). No eye had lost two or more Snellen lines of CDVA. CONCLUSIONS Myopic astigmatism correction with SmartSight provided good results for efficacy, safety, predictability, and visual outcomes at the twelve months of follow up. The central epithelial thickness barely increased by 3±2µm.
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Affiliation(s)
- Kishore Raj Pradhan
- Matrika Eye Center, Dhunge Dhara Marg, Ward number 9, Kathmandu 44600, Nepal.
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Clinical Evaluation of Corneal Biomechanics following Laser Refractive Surgery in Myopic Eyes: A Review of the Literature. J Clin Med 2022; 12:jcm12010243. [PMID: 36615041 PMCID: PMC9821300 DOI: 10.3390/jcm12010243] [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: 11/21/2022] [Revised: 12/18/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
The role of corneal biomechanics in laser vision correction (LVC) is currently being raised in the assessment of postoperative corneal ectasia risk. The aim of the paper was to evaluate the changes in corneal biomechanics after LVC procedures based on a systematic review of current studies. The results of a search of the literature in the PubMed, Science Direct, Google Scholar, and Web of Science databases were selected for final consideration according to the PRISMA 2020 flow diagram. Included in our review were 17 prospective clinical studies, with at least 6 months of follow-up time. Corneal biomechanical properties were assessed by Ocular Response Analyzer (ORA), or Corvis ST. The results of the study revealed the highest corneal biomechanics reduction after laser in situ keratomileusis (LASIK) followed by small incision lenticule extraction (SMILE) and surface procedures, such as photorefractive keratectomy (PRK) or laser-assisted sub-epithelial keratectomy (LASEK). In SMILE procedure treatment planning, the use of thicker caps preserves the corneal biomechanics. Similarly, reduction of flap thickness in LASIK surgery maintains the corneal biomechanical strength. Future prospective clinical trials with standardization of the study groups and surgical parameters are needed to confirm the results of the current review.
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Eskina E, Klokova O, Damashauskas R, Davtyan K, Pajic B, Movsesian M. Visual Outcomes of Small-Incision Lenticule Extraction (SMILE) in Thin Corneas. J Clin Med 2022; 11:jcm11144162. [PMID: 35887926 PMCID: PMC9324047 DOI: 10.3390/jcm11144162] [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: 05/24/2022] [Revised: 07/09/2022] [Accepted: 07/13/2022] [Indexed: 02/04/2023] Open
Abstract
We aimed to find out whether thin (≤500 μm) or normal (>500 μm, control) corneal thickness would impact efficacy and safety outcomes of small-incision lenticule extraction (SMILE). We retrospectively analyzed medical records of adult patients who had undergone SMILE. A total of 57 eyes were included in the “thin corneas” group and 180 eyes in the “control” group. At one month after surgery, rates of patients with uncorrected distance visual activity (UDVA) ≥ 0.8 were significantly higher in patients from the control group compared to the “thin corneas” group (87 vs. 71%, respectively p < 0.01), though rates were comparable at 3 months (87 vs. 76%, respectively, p > 0.05). SMILE had comparable safety in patients with thin and normal corneas. Procedure result predictability was comparable between groups. Regression analysis demonstrated that cap thickness impacted posterior corneal biomechanics, and the volume of removed tissue had a higher influence in patients with thin corneas. Moreover, an increase in cap thickness was associated with better final BCVA. Further study is needed for the evaluation of the impact of thin corneas on SMILE outcomes and planning. Our study also indicates that patients with thin corneas might require a different approach to nomogram calculation.
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Affiliation(s)
- Erika Eskina
- Ophthalmological Clinic “Sphere”, 117628 Moscow, Russia;
- Academy of Postgraduate Education of Federal State Budgetary Foundation Federal Research-Clinical Center Federal Medical-Biological Agency of Russia, 125310 Moscow, Russia
- Correspondence:
| | - Olga Klokova
- Krasnodar Branch of The Sviatoslav Fyodorov Eye Microsurgery Federal State Institution, 350012 Krasnodar, Russia; (O.K.); (R.D.)
| | - Roman Damashauskas
- Krasnodar Branch of The Sviatoslav Fyodorov Eye Microsurgery Federal State Institution, 350012 Krasnodar, Russia; (O.K.); (R.D.)
| | | | - Bojan Pajic
- Swiss Eye Research Foundation, Titlisstrasse 44, 5734 Reinach, Switzerland;
- Eye Clinic ORASIS, Titlisstrasse 44, 5734 Reinach, Switzerland
- Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, 1205 Geneva, Switzerland
- Faculty of Medicine, University of Geneva, 1205 Geneva, Switzerland
- Faculty of Sciences, Department of Physics, University of Novi Sad, Trg Dositeja Obradovica 4, 21102 Novi Sad, Serbia
- Faculty of Medicine of the Military Medical Academy, University of Defense, 11000 Belgrade, Serbia
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Wang Z, Song Y, Yang W, Li D, Chen W, Zhao Q, Liu Q, Zhai C. Comparing Standard Keratometry and Total Keratometry Before and After Myopic Corneal Refractive Surgery With a Swept-Source OCT Biometer. Front Med (Lausanne) 2022; 9:928027. [PMID: 35903314 PMCID: PMC9318577 DOI: 10.3389/fmed.2022.928027] [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: 04/27/2022] [Accepted: 06/13/2022] [Indexed: 11/29/2022] Open
Abstract
Background More recently, the swept-source OCT biometer-IOLMaster 700 has provided direct total corneal power measurement, named total keratometry. This study aims to evaluate whether standard keratometry (SK) and total keratometry (TK) with IOLMaster 700 can accurately reflect the corneal power changes induced by myopic corneal refractive surgery. Methods In this study, the biometric data measured with the swept-source OCT biometer—IOLMaster 700 before and 3 months after the myopic corneal refractive surgery were recorded. The changes of biological parameters, including SK, posterior keratometry (PK), and TK, and the difference between SK and TK were compared. In addition, the changes of SK and TK induced by the surgery were compared with the changes of spherical equivalent at the corneal plane (ΔSEco). Results A total of 74 eyes (74 patients) were included. The changes of SK, PK, TK, axial length, anterior chamber depth, and lens thickness after refractive surgery were all statistically significant (all p < 0.01), while the change of white-to-white was not (p = 0.075). The difference between SK and TK was −0.03 ± 0.10D before the corneal refractive surgery and increased to −0.78 ± 0.26D after surgery. The changes of SK and the changes of TK induced by the surgery had a good correlation with the changes of SEco (r = 0.97). ΔSK was significantly smaller than ΔSEco, with a difference of −0.65 ± 0.54D (p < 0.01). However, the difference between ΔTK and ΔSEco (0.10 ± 0.50D) was not statistically significant (p = 0.08). Conclusions Using SK to reflect the changes induced by the myopic corneal refractive surgery may lead to underestimation, while TK could generate a more accurate result. The new parameter, TK, provided by the IOLMaster 700, appeared to provide an accurate, objective measure of corneal power that closely tracked the refractive change in corneal refractive surgery.
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Lazaridis A, Spiru B, Giallouros E, Droutsas K, Messerschmidt-Roth A, Sekundo W. Corneal Remodeling After Myopic SMILE Versus FS-LASIK: A Spatial Analysis of Short- and Mid-Term Corneal Thickness, Volume, and Shape Changes. Cornea 2022; 41:826-832. [PMID: 34469342 DOI: 10.1097/ico.0000000000002833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 06/09/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate the short- and mid-term changes of corneal thickness spatial profile (CTSP), corneal volume distribution (CVD), and corneal asphericity after small-incision lenticule extraction (SMILE) for correction of myopia and astigmatism and compare the results with femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). METHOD Thirty eyes of 18 patients who underwent SMILE were compared with a group of 30 eyes of 16 patients who underwent FS-LASIK. The groups were matched for preoperative central corneal thickness and lenticule thickness/ablation depth. Scheimpflug corneal tomography was performed preoperatively and postoperatively at 2 months and 3 years. The CTSP was evaluated on 4 concentric rings (2, 4, 6, and 8 mm). The CVD was evaluated at 3 concentric zones (3, 5, and 7 mm). Changes in the anterior and posterior asphericity at a 6-mm zone were also evaluated. RESULTS Between the 2-month and 3-year examination, the CTSP showed a similar increase for both groups at all measured points and rings ( P ≥ 0.168). The CVD also showed a similar increase for both groups at all measured zones ( P ≥ 0.278). The anterior corneal asphericity remained stable after SMILE (2-mo Q = 0.46 ± 0.27; 3-yr Q = 0.45 ± 0.27; P = 0.711) but decreased significantly after FS-LASIK (2-mo Q = 0.52 ± 0.47; 3-yr Q = 0.47 ± 0.44; P = 0.028). Similarly, the posterior corneal asphericity remained stable after SMILE (2-mo Q = -0.11 ± 0.15; 3-yr Q = -0.11 ± 0.13; P = 0.902) but decreased significantly after FS-LASIK (2-mo Q = -0.13 ± 0.14; 3-yr Q = -0.16 ± 0.15; P = 0.034). CONCLUSIONS CTSP and CVD between the 2-month and 3-year examination showed a similar increase after SMILE and FS-LASIK. During the postoperative course, the anterior and posterior corneal asphericity remained more stable after SMILE compared with FS-LASIK.
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Affiliation(s)
- Apostolos Lazaridis
- Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany
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Wu Y, Sun S, Liu Z, Wang S, Wang G, Zhao S, Wei R, Huang Y. Changes in asphericity of anterior and posterior corneal surfaces for mild–moderate and high myopia after topography-guided FS-LASIK. Int Ophthalmol 2022; 42:3555-3565. [DOI: 10.1007/s10792-022-02356-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 04/18/2022] [Indexed: 10/18/2022]
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Cao H, Zhang L, Liang S, Chen X, Jhanji V, Wang Y. Predictive factors of posterior corneal shift after small incision lenticule extraction: a 5-year follow-up study. Acta Ophthalmol 2022; 100:e1431-e1438. [PMID: 35488809 DOI: 10.1111/aos.15166] [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: 09/22/2021] [Revised: 04/01/2022] [Accepted: 04/18/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE The aim of this study was to determine risk factors affecting changes in posterior corneal elevation (PCE) and predict the 5-year stability after small incision lenticule extraction (SMILE). METHODS This retrospective, longitudinal study enrolled 161 patients post-SMILE. The PCE values were measured at the apex, thinnest, maximal and 24 other prespecified preoperative points and at 6 months, 1 year and 5 years postoperatively. RESULTS Posterior corneas exhibited time-dependent, region-dependent and angle-dependent changes. For every dioptre increase in the absolute preoperative spherical equivalent (SE), 10-μm decrease in the central corneal thickness (CCT), 10-μm increase in the maximum lenticule thickness (MLT), 10-μm decrease in the residual bed thickness (RBT), 10% increase in the percentage ablation depth (PAD, MLT divided by CCT) and 10% decrease in the percentage stromal bed thickness (PSBT, RBT divided by CCT), PCE exhibited average forward displacements of 0.2-0.4, 0.2-0.7, 0.1-0.2, 0.1-0.3, 0.6-1.0 and 0.5-1.1 μm, respectively (p < 0.05). PSBT was the variable with the highest accuracy in predicting 5-year stability of posterior corneas (area under curve = 0.75). The cut-off values of SE, CCT, MLT, RBT, PAD and PSBT for increased PCE were -8.00 to -8.31 D, 481.0-498.5 μm, 139.5-144.5 μm, 255.5-263.5 μm, 26.9-28.3% and 48.9-52.6%, respectively. CONCLUSION Eyes with thinner corneas, higher myopia requiring greater MLT and lower RBT exhibited greater predispositions towards posterior protrusion. The thresholds for preventing forward posterior corneal displacement were 26.9-28.3% for PAD and 48.9-52.6% for PSBT. Prediction of posterior corneal stability is useful for assessing surgical risks post-SMILE.
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Affiliation(s)
- Huazheng Cao
- Clinical College of Ophthalmology Tianjin Medical University Tianjin China
| | - Lin Zhang
- Clinical College of Ophthalmology Tianjin Medical University Tianjin China
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute Nankai University Affiliated Eye Hospital Tianjin China
| | - Shuang Liang
- Clinical College of Ophthalmology Tianjin Medical University Tianjin China
| | - Xuan Chen
- Clinical College of Ophthalmology Tianjin Medical University Tianjin China
| | - Vishal Jhanji
- Department of Ophthalmology University of Pittsburgh School of Medicine Pittsburgh PA USA
| | - Yan Wang
- Clinical College of Ophthalmology Tianjin Medical University Tianjin China
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute Nankai University Affiliated Eye Hospital Tianjin China
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Zhang D, Qin X, Zhang H, Li L. Time-varying regularity of changes in biomechanical properties of the corneas after removal of anterior corneal tissue. Biomed Eng Online 2021; 20:113. [PMID: 34801040 PMCID: PMC8606087 DOI: 10.1186/s12938-021-00948-7] [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: 05/10/2021] [Accepted: 11/03/2021] [Indexed: 11/13/2022] Open
Abstract
Background The corneal biomechanical properties with the prolongation of time after corneal refractive surgery are important for providing a mechanical basis for the occurrence of clinical phenomena such as iatrogenic keratectasia and refractive regression. The aim of this study was to explore the changes of corneal elastic modulus, and stress relaxation properties from the 6-month follow-up observations of rabbits after a removal of anterior corneal tissue in simulation to corneal refractive surgery. Methods The anterior corneal tissue, 6 mm in diameter and 30–50% of the original corneal thickness, the left eye of the rabbit was removed, and the right eye was kept as the control. The rabbits were normally raised and nursed for 6 months, during which corneal morphology data, and both of corneal hysteresis (CH) and corneal resistance factor (CRF) were gathered. Uniaxial tensile tests of corneal strips were performed at months 1, 3, and 6 from 7 animals, and corneal collagen fibrils were observed at months 1, 3, and 6 from 1 rabbit, respectively. Results Compared with the control group, there were statistical differences in the curvature radius at week 2 and month 3, and both CH and CRF at months 1, 2, and 6 in experiment group; there were statistical differences in elastic modulus at 1, 3, and month 6, and stress relaxation degree at month 3 in experiment group. The differences in corneal elastic modulus, stress relaxation degree and the total number of collagen fibrils between experiment and control groups varied gradually with time, and showed significant changes at the 3rd month after the treatment. Conclusions Corneas after a removal of anterior corneal tissue undergo dynamic changes in corneal morphology and biomechanical properties. The first 3 months after treatment could be a critical period. The variation of corneal biomechanical properties is worth considering in predicting corneal deformation after a removal of anterior corneal tissue.
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Affiliation(s)
- Di Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Xiao Qin
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Haixia Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
| | - Lin Li
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
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Predictability of intraocular lens power calculation after small-incision lenticule extraction for myopia. J Cataract Refract Surg 2021; 47:304-310. [PMID: 32932366 DOI: 10.1097/j.jcrs.0000000000000405] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 08/03/2020] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate and compare the predictability of intraocular lens (IOL) power calculation after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism. SETTING Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany. DESIGN Retrospective comparative case series. METHODS Preoperative evaluation included optical biometry using IOLMaster 500 and corneal tomography using Pentacam HR. The corneal tomography measurements were repeated at 3 months postoperatively. The change of spherical equivalent due to SMILE was calculated by the manifest refraction at corneal plane (SMILE-Dif). A theoretical model, involving the virtual implantation of the same IOL before and after SMILE, was used, and the IOL power calculations were performed using ray tracing (OKULIX, version 9.06) and third- (Hoffer Q, Holladay 1, and SRK/T) and fourth-generation (Haigis-L and Haigis) formulas. The difference between the IOL-induced refractive error at corneal plane before and after SMILE (IOL-Dif) was compared with SMILE-Dif. The prediction error (PE) was calculated as the difference between SMILE-Dif-IOL-Dif. RESULTS The study included 204 eyes that underwent SMILE. The PE with ray tracing was -0.06 ± 0.40 diopter (D); Haigis-L, -0.39 ± 0.62 D; Haigis, 0.70 ± 0.48 D; Hoffer Q, 0.84 ± 0.47 D; Holladay 1, 1.21 ± 0.51 D; and SRK/T, 1.46 ± 0.54 D. The PE with ray tracing was significantly smaller compared with that of all formulas (P ≤ .001). The PE variance with ray tracing was σ2 = 0.159, being significantly more homogenous compared with that of all formulas (P ≤ .011, F ≥ 6.549). Ray tracing resulted in an absolute PE of 0.5 D or lesser in 81.9% of the cases, followed by Haigis-L (53.4%), Haigis (35.3%), Hoffer Q (25.5%), Holladay 1 (6.4%), and SRK/T (2.9%) formulas. CONCLUSIONS Ray tracing was the most accurate approach for IOL power calculation after myopic SMILE.
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Liu J, Wang Y. Influence of Preoperative Keratometry on Refractive Outcomes for Myopia Correction With Small Incision Lenticule Extraction. J Refract Surg 2021; 36:374-379. [PMID: 32521024 DOI: 10.3928/1081597x-20200513-01] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 05/13/2020] [Indexed: 01/29/2023]
Abstract
PURPOSE To evaluate the effect of preoperative keratometry on refractive outcomes after small incision lenticule extraction (SMILE) for myopia. METHODS This retrospective study comprised 515 consecutive eyes that had SMILE to correct myopia. Pearson correlation and linear regression were used to determine the relationship between residual spherical equivalent and preoperative keratometry. The same analyses were repeated in the quartiles with the lowest and highest preoperative myopia. RESULTS Preoperatively, the mean spherical equivalent was -5.67 ± 1.87 diopters (D) (range: -1.63 to -9.75 D) and the mean keratometry was 43.10 ± 1.30 D (range: 38.90 to 47.00 D). Three months postoperatively, the mean spherical equivalent was -0.07 ± 0.18 D. After adjustment for age, sex, and preoperative spherical equivalent, greater postoperative undercorrection occurred in eyes with steeper corneas (P = .001). Each diopter of steeper keratometry resulted in 0.52% (0.03 D) more undercorrection. Correlation between the mean preoperative keratometry and residual spherical equivalent was significant in the lower preoperative myopia group (r = -0.24, P = .006), but not significant in the higher myopia group (r = -0.02, P = .809). CONCLUSIONS Preoperative keratometry affects refractive outcomes after SMILE. Steeper corneas have greater undercorrection, especially in eyes with low myopia. Knowledge of the correlation between refractive outcomes of SMILE and keratometry would help in modifying current treatment algorithms. [J Refract Surg. 2020;36(6):374-379.].
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Arba Mosquera S, Verma S. A review of clinical outcomes following SMILE for the treatment of astigmatism. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2020.1810017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Samuel Arba Mosquera
- Biomedical Engineering Office, Research and Development, SCHWIND Eye-tech-solutions GmbH, Kleinostheim, Germany
| | - Shwetabh Verma
- Biomedical Engineering Office, Research and Development, SCHWIND Eye-tech-solutions GmbH, Kleinostheim, Germany
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Cui T, Wang Y, Ji S, Li Y, Hao W, Zou H, Jhanji V. Applying Machine Learning Techniques in Nomogram Prediction and Analysis for SMILE Treatment. Am J Ophthalmol 2020; 210:71-77. [PMID: 31647929 DOI: 10.1016/j.ajo.2019.10.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 09/24/2019] [Accepted: 10/10/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE To analyze the outcome of machine learning technique for prediction of small incision lenticule extraction (SMILE) nomogram. DESIGN Prospective, comparative clinical study. METHODS A comparative study was conducted on the outcomes of SMILE surgery between surgeon group (nomogram set by surgeon) and machine learning group (nomogram predicted by machine learning model). The machine learning model was trained by 865 ideal cases (spherical equivalent [SE] within ±0.5 diopter [D] 3 months postoperatively) from an experienced surgeon. The visual outcomes of both groups were compared for safety, efficacy, predictability, and SE correction. RESULTS There was no statistically significant difference between the baseline data in both groups. The efficacy index in the machine learning group (1.48 ± 1.08) was significantly higher than in the surgeon group (1.3 ± 0.27) (t = -2.17, P < .05). Eighty-three percent of eyes in the surgeon group and 93% of eyes in the machine learning group were within ±0.50 D, while 98% of eyes in the surgeon group and 96% of eyes in the machine learning group were within ±1.00 D. The error of SE correction was -0.09 ± 0.024 and -0.23 ± 0.021 for machine learning and surgeon groups, respectively. CONCLUSIONS The machine learning technique performed as well as surgeon in safety, but significantly better than surgeon in efficacy. As for predictability, the machine learning technique was comparable to surgeon, although less predictable for high myopia and astigmatism.
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Kim BK, Mun SJ, Yang YH, Kim JS, Moon JH, Chung YT. Comparison of anterior segment changes after femtosecond laser LASIK and SMILE using a dual rotating Scheimpflug analyzer. BMC Ophthalmol 2019; 19:251. [PMID: 31829164 PMCID: PMC6907211 DOI: 10.1186/s12886-019-1257-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 11/22/2019] [Indexed: 12/27/2022] Open
Abstract
Background To compare the changes in the anterior segment after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) using a dual rotating Scheimpflug (DRS) analyzer (Galilei®; Ziemer Ophthalmology, Port, Switzerland). Methods A total of 218 eyes of 109 patients who underwent FS-LASIK or SMILE for myopic correction were retrospectively studied. Ninety-eight eyes of 49 patients who underwent FS-LASIK were compared to 120 eyes of 60 patients treated with SMILE. A DRS analyzer was used for preoperative and 6-month postoperative anterior segment analyses. Measured variables included the central corneal thickness (CCT), anterior chamber depth (ACD), anterior and posterior keratometry (K), anterior and posterior best-fit sphere radius, and maximum posterior elevation (MPE). Results After the procedure, the amount of CCT decrease was higher in the SMILE group than in the FS-LASIK group, but it was not statistically significant. The MPE was significantly increased after both procedures (p < 0.001 and p = 0.001 in the FS-LASIK and SMILE groups, respectively), with the amount of elevation being higher after FS-LASIK than after SMILE even though it was not statistically significant. And there was a significant change in the steep and average posterior K in the FS-LASIK group (p = 0.006 and 0.001, respectively), but not in the SMILE group. Conclusions Regarding changes in the MPE and posterior K, changes in the posterior corneal surface were greater after FS-LASIK than after SMILE. Trial registration The trial registration number: KCT0003628. Date of registration: 15 March 2019.
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Affiliation(s)
- Bu Ki Kim
- Onnuri Smile Eye Clinic, Hyobong building 9F 1, Gangnam-daero 65 gil, Seocho-gu, Seoul, Republic of Korea
| | - Su Joung Mun
- Onnuri Eye Hospital, 325, Baekje-daero, Wansan-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Young Hoon Yang
- Onnuri Eye Hospital, 325, Baekje-daero, Wansan-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Ji Sun Kim
- Onnuri Smile Eye Clinic, Hyobong building 9F 1, Gangnam-daero 65 gil, Seocho-gu, Seoul, Republic of Korea
| | - Jun Hyung Moon
- Onnuri Eye Hospital, 325, Baekje-daero, Wansan-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Young Taek Chung
- Onnuri Eye Hospital, 325, Baekje-daero, Wansan-gu, Jeonju-si, Jeollabuk-do, Republic of Korea.
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Fourier Analysis of Corneal Irregular Astigmatism After Small Incision Lenticule Extraction and Comparison to Femtosecond Laser-Assisted Laser In Situ Keratomileusis. Cornea 2019; 38:1536-1542. [DOI: 10.1097/ico.0000000000002029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Zhou X, Shang J, Qin B, Zhao Y, Zhou X. Two-year observation of posterior corneal elevations after small incision lenticule extraction (SMILE) for myopia higher than -10 dioptres. Br J Ophthalmol 2019; 104:142-148. [PMID: 31036587 PMCID: PMC6922016 DOI: 10.1136/bjophthalmol-2018-313498] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 02/05/2019] [Accepted: 03/29/2019] [Indexed: 12/01/2022]
Abstract
Aim To investigate the change in posterior corneal elevations (PCEs) of eyes with extremely high myopia 2 years after small incision lenticule extraction (SMILE). Methods We evaluated 39 eyes of 39 patients with spherical equivalent higher than −10.00 dioptres (D). Using a Scheimpflug camera (Pentacam), we measured change in PCEs at 1 day, 3 months, 6 months and 2 years after SMILE. Another 34 eyes of 34 patients who underwent femtosecond laser-assisted in situ keratomileusis (FS-LASIK) were examined before, at 1 day and long-term after surgery as the control group. For each eye, elevations at central, thinnest, maximal points and 24 other predetermined points were measured. Results No significant forward displacements of PCEs were observed in both surgeries. The maximal but not significant forward displacement occurred around 3–6 months following SMILE, and all returned to original levels 6 months postoperatively except superior area. The peripheral area tended to displace backward, while the central area tended forwardly. In both procedures, elevations along horizontal meridians, inferior and temporal hemispheres were significantly higher than those along vertical meridians, superior and nasal hemispheres, respectively (p<0.05). Elevation on the 4 mm, 6 mm diameters at 1 day and on the 6 mm diameter and temporal hemisphere at long-term follow-up postoperatively were significantly higher in FS-LASIK than SMILE (p<0.05). Change in elevations on the 6 mm diameter circle correlated with residual bed thickness (p=0.047). Conclusions SMILE is a safe way to correct for myopia higher than −10 D, with PCEs remaining stable 2 years after surgery.
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Affiliation(s)
- Xueyi Zhou
- Ophthalmology, Eye and ENT Hospital of Fudan University, NHC Key Laboratory of Myopia, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jianmin Shang
- Ophthalmology, Eye and ENT Hospital of Fudan University, NHC Key Laboratory of Myopia, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Bing Qin
- Ophthalmology, Eye and ENT Hospital of Fudan University, NHC Key Laboratory of Myopia, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yu Zhao
- Ophthalmology, Eye and ENT Hospital of Fudan University, NHC Key Laboratory of Myopia, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xingtao Zhou
- Ophthalmology, Eye and ENT Hospital of Fudan University, NHC Key Laboratory of Myopia, Shanghai, China .,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
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Corneal Irregular Astigmatism and Curvature Changes After Small Incision Lenticule Extraction: Three-Year Follow-Up. Cornea 2018; 37:875-880. [DOI: 10.1097/ico.0000000000001532] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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La prédictibilité du SMILE sur quatre ans chez les myopes forts. J Fr Ophtalmol 2017; 40:561-570. [DOI: 10.1016/j.jfo.2017.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/09/2017] [Accepted: 01/17/2017] [Indexed: 11/22/2022]
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Abulafia A, Hill WE, Wang L, Reitblat O, Koch DD. Intraocular Lens Power Calculation in Eyes After Laser In Situ Keratomileusis or Photorefractive Keratectomy for Myopia. Asia Pac J Ophthalmol (Phila) 2017; 6:332-338. [PMID: 28780776 DOI: 10.22608/apo.2017187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/25/2017] [Indexed: 11/08/2022] Open
Abstract
Intraocular power calculation is challenging for patients who have previously undergone corneal refractive surgery. The sources of prediction errors for these eyes are well known; however, the numerous formulas and methods available for calculating intraocular lens power in these cases are eloquent testimony to the absence of a definitive solution. This review discusses some of the available methods for improving the accuracy for predicting the refractive outcome for these patients. It focuses mainly on the methods available on the American Society of Cataract and Refractive Surgery (ASCRS) online calculator and provides some practical guidelines for cataract surgeons who encounter these challenging cases.
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Affiliation(s)
- Adi Abulafia
- Shaare Zedek Medical Centre, Jerusalem, Israel
- Hebrew University of Jerusalem, Jersusalem, Israel
| | | | - Li Wang
- Cullen Eye Institute, Baylor College of Medicine, Houston, Texas
| | - Olga Reitblat
- Shaare Zedek Medical Centre, Jerusalem, Israel
- Hebrew University of Jerusalem, Jersusalem, Israel
| | - Douglas D Koch
- Cullen Eye Institute, Baylor College of Medicine, Houston, Texas
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Burazovitch J, Naguzeswski D, Beuste T, Guillard M. Predictability of SMILE over four years in high myopes. J Fr Ophtalmol 2017; 40:e201-e209. [DOI: 10.1016/j.jfo.2017.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 04/25/2017] [Accepted: 05/02/2017] [Indexed: 10/19/2022]
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Koch DD. The Enigmatic Cornea and Intraocular Lens Calculations: The LXXIII Edward Jackson Memorial Lecture. Am J Ophthalmol 2016; 171:xv-xxx. [PMID: 27562430 DOI: 10.1016/j.ajo.2016.08.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 11/18/2022]
Abstract
PURPOSE To review the progress and challenges in obtaining accurate corneal power measurements for intraocular lens (IOL) calculations. DESIGN Personal perspective, review of literature, case presentations, and personal data. METHODS Through literature review findings, case presentations, and data from the author's center, the types of corneal measurement errors that can occur in IOL calculation are categorized and described, along with discussion of future options to improve accuracy. RESULTS Advances in IOL calculation technology and formulas have greatly increased the accuracy of IOL calculations. Recent reports suggest that over 90% of normal eyes implanted with IOLs may achieve accuracy to within 0.5 diopter (D) of the refractive target. Though errors in estimation of corneal power can cause IOL calculation errors in eyes with normal corneas, greater difficulties in measuring corneal power are encountered in eyes with diseased, scarred, and postsurgical corneas. For these corneas, problematic issues are quantifying anterior corneal power and measuring posterior corneal power and astigmatism. Results in these eyes are improving, but 2 examples illustrate current limitations: (1) spherical accuracy within 0.5 D is achieved in only 70% of eyes with post-refractive surgery corneas, and (2) astigmatism accuracy within 0.5 D is achieved in only 80% of eyes implanted with toric IOLs. CONCLUSION Corneal power measurements are a major source of error in IOL calculations. New corneal imaging technology and IOL calculation formulas have improved outcomes and hold the promise of ongoing progress.
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Affiliation(s)
- Douglas D Koch
- Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas.
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He M, Wang W, Ding H, Zhong X. Comparison of Two Cap Thickness in Small Incision Lenticule Extraction: 100μm versus 160μm. PLoS One 2016; 11:e0163259. [PMID: 27655417 PMCID: PMC5031463 DOI: 10.1371/journal.pone.0163259] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/05/2016] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To compare the changes of biomechanical properties, endothelial cell density (ECD), and posterior corneal elevation (PCE) after femtosecond small incision lenticule extractions (SMILEs) with 100μm versus 160μm cap thicknesses. METHODS A total of 12 rabbits were randomly assigned into two groups of 6 each. SMILE was performed at a depth of either 160μm (160-cap group) or 100μm (100-cap group). Corneal biomechanics, PCE, ECD were evaluated pre-operatively, 1week, 1 month, 2 months, 3 months, and 4 months post-operatively by Pentacam, Corvis ST, in vivo confocal microscopy (IVCM) respectively. The Young's modulus was obtained by strip-extensometry test 4 months after surgery. RESULTS At each time point, the second applanation time (A2T) was similar between the groups with the exception of 4 months after surgery (22.66±0.16 ms in the 160-cap group versus 21.75±0.29 ms in the 100-cap group, p = 0.004). Neither deformation amplitude (DA) nor the first applanationtime (A1T) were significantly different between the two groups. The postoperative posterior surface did not shift forward, the changes of PCE and ECD were not significantly different between the two groups at any observation time. Young's modulus was higher in the 160-cap group than that in the 100-cap group with no statistical significance (P>0.05). Regression analyses showed that the PCE changes and Young's modulus were not affected by cap thickness (CT) or residual stromal bed thickness (RBT) (All P>0.05). CONCLUSIONS The differences of corneal biomechanics, posterior surface elevation, or ECD changes were quite small when using 100μm or 160μm cap thicknesses in SMILE.
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Affiliation(s)
- Miao He
- Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Wei Wang
- Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Hui Ding
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan Province, China
| | - Xingwu Zhong
- Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People’s Republic of China
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan Province, China
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