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Li Y, Yang Y, Shen M, Wang C, Chang L, Liu T, Wang Y. Investigation of the optimal cutting depth in small incision lenticule extraction based on a collagen fibril crimping constitutive model of the cornea. J Biomech 2024; 169:112145. [PMID: 38761745 DOI: 10.1016/j.jbiomech.2024.112145] [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: 11/01/2023] [Revised: 04/30/2024] [Accepted: 05/08/2024] [Indexed: 05/20/2024]
Abstract
To investigate the optimal cutting depth (Cap) in small incision lenticule extraction from the perspective of corneal biomechanics, a three-dimensional finite element model of the cornea was established using a stromal sub-regional material model to simulate small incision lenticule extraction. The displacement difference PΔ at the central point of the posterior corneal surface before and after lenticule extraction, as well as the von Mises stress at four points of different thicknesses in the center of the cornea, were analyzed using the finite element model considering the hyperelastic property and the difference in stiffness between the anterior and posterior of the cornea. The numerical curves of PΔ-Cap and von Mises Stress-Cap relations at different diopters show that the displacement difference PΔ has a smallest value at the same diopter. In this case, the von Mises stress at four points with different thicknesses in the center of the cornea was also minimal. Which means that the optimal cutting depth exsisting in the cornea. Moreover, PΔ-Cap curves for different depth of stromal stiffness boundaries show that the optimal cap thickness would change with the depth of the stromal stiffness boundary. These results are of guiding significance for accurately formulating small incision lenticule extraction surgery plans and contribute to the advancement of research on the biomechanical properties of the cornea.
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Affiliation(s)
- Yikuan Li
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
| | - Yaqing Yang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
| | - Min Shen
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China.
| | - Congzheng Wang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
| | - Le Chang
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, Tianjin 300020, China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070, China
| | - Taiwei Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China; Department of Engineering Mechanics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China
| | - Yan Wang
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, Tianjin 300020, China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070, China.
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Liu M, Li N, Chen T, Tian G, Lin Y, Gao H, Shi W. Comparison of Corneal Biomechanics Treated With Femtosecond Laser-Assisted In Situ Keratomileusis and Small-Incision Lenticule Extraction by New Corneal Biomechanical Parameters of Corvis ST II. Cornea 2023; 42:1384-1390. [PMID: 36729642 DOI: 10.1097/ico.0000000000003191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/27/2022] [Indexed: 02/03/2023]
Abstract
PURPOSE The aim of this study was to compare corneal biomechanics treated with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small-incision lenticule extraction (SMILE) for myopia and astigmatism using the new corneal biomechanical parameters of Corvis ST II. METHODS This was a prospective nonrandomized controlled study. Patients treated with FS-LASIK or SMILE between January 2018 and July 2018 were included. Corvis ST II was performed to measure corneal biomechanical parameters, including deformation amplitude ratio 2.0 mm (DA ratio 2.0 mm), integrated inverse radius (Integr Radius), stiffness parameter at first applanation (SP-A1), and Ambrosio relational thickness through the horizontal meridian (ARTh), preoperatively, 1 month postoperatively, and 6 months postoperatively. Pentacam pachymetry was used to assess the reduction in pachymetry. RESULTS Forty-five eyes underwent FS-LASIK, and 45 eyes underwent SMILE. The new parameters obtained by Corvis ST II between preoperative and postoperative measurements showed significant changes after FS-LASIK or SMILE (all P < 0.001). Postoperative SP-A1 significantly decreased in the 2 groups (108.88 ± 14.47-73.32 ± 13.2 in FS-LASIK and 105.79 ± 17.68-73.91 ± 14.81 in SMILE). Eyes with equal preoperative pachymetry, intraocular pressure, and spherical equivalents showed no significant differences in these new parameters measured using Corvis ST II ( all P > 0.05) between the 2 groups. The prediction of the laser platform overestimated the measured pachymetry reduction in the SMILE group (111.93 ± 15.18 μm vs. 87.16 ± 15.47 μm). CONCLUSIONS New corneal biomechanical parameters measured using Corvis ST II showed no significant differences between FS-LASIK and SMILE in eyes with homogeneous preoperative parameters. The laser software platform may have overestimated the actual corneal reduction in the eyes treated with SMILE.
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Affiliation(s)
- Mingna Liu
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Na Li
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Tong Chen
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Ge Tian
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Yue Lin
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Hua Gao
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
| | - Weiyun Shi
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Jinan, China ; and
- School of Ophthalmology, Shandong First Medical University, Jinan, China
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Nambiar MH, Liechti L, Studer H, Roy AS, Seiler TG, Büchler P. Patient-specific finite element analysis of human corneal lenticules: An experimental and numerical study. J Mech Behav Biomed Mater 2023; 147:106141. [PMID: 37748318 DOI: 10.1016/j.jmbbm.2023.106141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/05/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023]
Abstract
The number of elective refractive surgeries is constantly increasing due to the drastic increase in myopia prevalence. Since corneal biomechanics are critical to human vision, accurate modeling is essential to improve surgical planning and optimize the results of laser vision correction. In this study, we present a numerical model of the anterior cornea of young patients who are candidates for laser vision correction. Model parameters were determined from uniaxial tests performed on lenticules of patients undergoing refractive surgery by means of lenticule extraction, using patient-specific models of the lenticules. The models also took into account the known orientation of collagen fibers in the tissue, which have an isotropic distribution in the corneal plane, while they are aligned along the corneal curvature and have a low dispersion outside the corneal plane. The model was able to reproduce the experimental data well with only three parameters. These parameters, determined using a realistic fiber distribution, yielded lower values than those reported in the literature. Accurate characterization and modeling of the cornea of young patients is essential to study better refractive surgery for the population undergoing these treatments, to develop in silico models that take corneal biomechanics into account when planning refractive surgery, and to provide a basis for improving visual outcomes in the rapidly growing population undergoing these treatments.
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Affiliation(s)
- Malavika H Nambiar
- ARTORG Center for Biomedical Engineering Research, University of Bern, Freiburgstrasse 3, 3010, Bern, Switzerland.
| | - Layko Liechti
- ARTORG Center for Biomedical Engineering Research, University of Bern, Freiburgstrasse 3, 3010, Bern, Switzerland.
| | - Harald Studer
- Optimo Medical, Robert-Walser-Platz 7, 2503, Biel, Switzerland.
| | - Abhijit S Roy
- Narayana Nethralaya Eye Clinic, Bengaluru, Karnataka, 560010, India.
| | - Theo G Seiler
- IROC AG, Institut für Refraktive und Ophthalmo-Chirurgie, Stockerstrasse 37, 8002, Zürich, Switzerland; Universitätsklinik für Augenheilkunde, Inselspital Bern, Freiburgstrasse 15, 3010, Bern, Switzerland; Klinik für Augenheilkunde, Universitätsklinikum Düsseldorf, Moorenstr. 5, 40225, Düsseldorf, Germany.
| | - Philippe Büchler
- ARTORG Center for Biomedical Engineering Research, University of Bern, Freiburgstrasse 3, 3010, Bern, Switzerland.
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Yang S, Huang T, Wang Y, Ning K, Long Q, Wang Z, Li Y, Chen D. Short-Term Impact of Different Corneal Incision Positions on Postoperative Astigmatism and Visual Quality After SMILE Surgery. Ophthalmol Ther 2023; 12:2453-2464. [PMID: 37328617 PMCID: PMC10441924 DOI: 10.1007/s40123-023-00748-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 05/31/2023] [Indexed: 06/18/2023] Open
Abstract
INTRODUCTION This study aimed to evaluate the short-term impact of different incision positions on astigmatism and visual quality after small incision lenticule extraction (SMILE) surgery. METHODS This prospective study enrolled patients who decided to have SMILE to correct myopia. Patients were randomly allocated into three groups of different incision positions (group A, B, and C with incision position at 90°, 120°, and 150° respectively). Preoperative and postoperative visual acuity, spherical equivalent, and high-order aberrations (HOAs) were measured and compared among groups. Astigmatism was analyzed with the ASSORT Group Analysis Calculator based on the Alpins method. RESULTS A total of 148 eyes were included for analysis (48 eyes in group A, 50 eyes in group B, and 50 eyes in group C). At 1 month postoperatively, the mean uncorrected distance visual acuity (UDVA) logMAR in group A, B, and C was - 0.03, - 0.03, and - 0.04, respectively. The mean corrected distance visual acuity (CDVA) logMAR in group A, B, and C was - 0.03, - 0.04, and - 0.04, respectively (P > 0.05). The mean postoperative spherical equivalent (SE) values were - 0.01 ± 0.38, - 0.07 ± 0.39, and - 0.16 ± 0.49 (D) in group A, B, and C, respectively (P > 0.05). There was no statistically significant difference in preoperative and postoperative magnitude of astigmatism among different groups (P > 0.05). Significant differences were found in the distribution of astigmatism axis among the three groups at 1 day (P = 0.02) and 1 week (P = 0.02) postoperatively. However, such differences were no longer significant at 1 month after surgery (P > 0.05). No significant differences were found in HOAs among different groups 1 month after surgery (P > 0.05). CONCLUSION Different incision positions have no effect on postoperative astigmatism and visual quality 1 month after SMILE surgery, though differences were found in the distribution of the astigmatism axis within 1 week after the surgery.
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Affiliation(s)
- Shan Yang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Tianze Huang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Yuchen Wang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Ken Ning
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Qing Long
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Zhonghai Wang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Ying Li
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China
| | - Di Chen
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan 1, Dongcheng District, Beijing, 100005, China.
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Chen S, Ma H, Zhao C. Corneal biomechanics after small incision lenticule extraction and femtosecond laser in situ keratomileusis: A systematic review and meta-analysis. Medicine (Baltimore) 2023; 102:e34580. [PMID: 37565903 PMCID: PMC10419641 DOI: 10.1097/md.0000000000034580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 07/13/2023] [Indexed: 08/12/2023] Open
Abstract
BACKGROUND Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) have been extensively studied as the main surgical methods for corneal refractive surgery. However, there is no consensus on whether SMILE is superior to FS-LASIK in corneal biomechanics. Therefore, this systematic review and meta-analysis used the results of ocular response analyzer and corvis ST to explore whether SMILE is superior to FS-LASIK in corneal biomechanics. METHODS The literature was searched in PubMed, EMBASE, and Controlled Trials Register databases. The Cochrane Collaboration's "risk of bias" tool was used to evaluate the quality of the included randomized clinical trials, and the Newcastle-Ottawa Scale was used to evaluate the included non-randomized controlled trials. The results were analyzed using Revman 5.3. RESULTS Sixteen studies (3 randomized clinical trials and 13 non-randomized controlled trials) were included in this meta-analysis. There was no statistical difference in corneal biomechanics between SMILE and FS-LASIK in corneal hysteresis [mean difference (MD), 0.20; 95% confidence interval (CI): -0.09, 0.49; P = .18] and corneal resistant factor (MD, 0.31; 95% CI: -0.09, 0.71; P = .13), A1 time (MD, -0.02; 95% CI: -0.11, 0.07; P = .66), A1 length (MD, 0.01; 95% CI: -0.01, 0.03; P = .42), A1 velocity (MD, 0.00; 95% CI: -0.01, 0.01; P = .85), A2 velocity (MD, -0.01; 95% CI: -0.11, 0.09; P = .86), HC time (MD, 0.12; 95% CI: -0.13, 0.38; P = .35), The stiffness parameter at first applanation (MD, -7.91; 95% CI: -17.96, 2.14; P = .12), The ratio between the deformation amplitude 2 mm away from apex and the apical deformation (MD, 0.01; 95% CI: -0.26, 0.27; P = .96). CONCLUSION A comprehensive assessment of the parameters of ocular response analyzer and corvis ST showed that SMILE is not superior to LASIK in corneal biomechanics 3 months post-surgery.
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Affiliation(s)
- Songbai Chen
- Aier Huangpi Eye Hospital, Wuhan, Hubei Province, China
| | - Hongjie Ma
- Zhengzhou Aier Eye Hospital, Zhengzhou, Henan Province, China
| | - Congling Zhao
- Aier Huangpi Eye Hospital, Wuhan, Hubei Province, China
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Yang F, Dong Y, Bai C, Alzogool M, Wang Y. Bibliometric and visualized analysis of myopic corneal refractive surgery research: from 1979 to 2022. Front Med (Lausanne) 2023; 10:1141438. [PMID: 37575980 PMCID: PMC10416457 DOI: 10.3389/fmed.2023.1141438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 07/14/2023] [Indexed: 08/15/2023] Open
Abstract
Background Myopic corneal refractive surgery is one of the most prevalent ophthalmic procedures for correcting ametropia. This study aimed to perform a bibliometric analysis of research in the field of corneal refractive surgery over the past 40 years in order to describe the current international status and to identify most influential factors, while highlighting research hotspots. Methods A bibliometric analysis based on the Web of Science Core Collection (WoSCC) was used to analyze the publication trends in research related to myopic corneal refractive surgery. VOSviewer v.1.6.10 was used to construct the knowledge map in order to visualize the publications, distribution of countries, international collaborations, author productivity, source journals, cited references, keywords, and research hotspots in this field. Results A total of 4,680 publications on myopic corneal refractive surgery published between 1979 and 2022 were retrieved. The United States has published the most papers, with Emory University contributing to the most citations. The Journal of Cataract and Refractive Surgery published the greatest number of articles, and the top 10 cited references mainly focused on outcomes and wound healing in refractive surgery. Previous research emphasized "radial keratotomy (RK)" and excimer laser-associated operation methods. The keywords containing femtosecond (FS) laser associated with "small incision lenticule extraction (SMILE)" and its "safety" had higher burst strength, indicating a shift of operation methods and coinciding with the global trends in refractive surgery. The document citation network was clustered into five groups: (1) outcomes of refractive surgery: (2) preoperative examinations for refractive surgery were as follows: (3) complications of myopic corneal refractive surgery; (4) corneal wound healing and cytobiology research related to photorefractive laser keratotomy; and (5) biomechanics of myopic corneal refractive surgery. Conclusion The bibliometric analysis in this study may provide scholars with valuable to information and help them better understand the global trends in myopic corneal refractive surgery research frontiers. Two stages of rapid development occurred around 1991 and 2013, shortly after the innovation of PRK and SMILE surgical techniques. The most cited articles mainly focused on corneal wound healing, clinical outcomes, ocular aberration, corneal ectasia, and corneal topography, representing the safety of the new techniques.
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Affiliation(s)
- Fang Yang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Department of Ophthalmology, Renmin Hospital, Hubei University of Medicine, Shiyan, China
| | - Yi Dong
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
| | - Chen Bai
- Department of General Surgery, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Mohammad Alzogool
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
- School of Medicine, Nankai University, Tianjin, China
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
- Nankai Eye Institute, Nankai University, Tianjin, China
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Chen L, Huang Y, Zhang X, Shi Y, Gao Z, Sun B, Shen Y, Sun L, Cao Y, Zhang Q, Guo J, Li F, Chen W, Li X, Zhou X. Corneal Biomechanical Properties Demonstrate Anisotropy and Correlate With Axial Length in Myopic Eyes. Invest Ophthalmol Vis Sci 2023; 64:27. [PMID: 37477932 PMCID: PMC10365135 DOI: 10.1167/iovs.64.10.27] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 06/12/2023] [Indexed: 07/22/2023] Open
Abstract
Purpose The purpose of this study was to investigate the ex vivo and in vivo biomechanical characteristic of cornea in myopic eyes. Methods Fifty-one corneal stromal lenticules were obtained from myopic eyes during the SMILE procedure and were tested by a biaxial tensile system within 24 hours postoperatively. The material properties of the lenticules were described using stress-strain curves and were compared among axial length (AL) <26 mm and AL ≥ 26 mm group. Pre-operative stress-strain index (SSI) parameters were used to evaluate the biomechanical properties of the cornea in vivo. Results Compared with AL < 26 mm, the tangent modulus significantly decreased in horizontal and vertical directions when AL ≥ 26 mm (P < 0.05); SSI also significantly decreased when AL ≥ 26 mm (P < 0.05). Anisotropic parameter is positively correlated with AL (r = 0.307, P < 0.05). Compared with AL < 26 mm, anisotropic parameter significantly increased when AL ≥ 26 mm (P < 0.05). SSI was negatively correlated with AL (r = -0.380, P < 0.05) in the AL < 26 mm group but not in the AL ≥ 26 mm group (P > 0.05). Compared with 26 mm ≤ AL < 27 mm group, the tangent modulus significantly decreased in the horizontal direction (P < 0.05) but not in the vertical direction when 27 mm ≤ AL < 28 mm (P > 0.05). Conclusions The biomechanical properties of cornea decreased with the increase of AL. Tangent modulus significantly decreased in the horizontal direction compared with vertical direction. AL should be taken into account during calculation of corneal biomechanical parameters in order to improve validity.
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Affiliation(s)
- Lingfeng Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Yangyi Huang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Xiaoyu Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yike Shi
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Zhipeng Gao
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Bingqing Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yang Shen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Ling Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yifan Cao
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Qianqian Zhang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
- Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University, Taiyuan, China
- School of Automation and Software Engineering, Shanxi University, Taiyuan, Shanxi, China
| | - Jiqiang Guo
- Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University, Taiyuan, China
| | - Fen Li
- College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan, China
- Institute of Applied Mechanics, Taiyuan University of Technology, Taiyuan, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Xiaona Li
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Xingtao Zhou
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
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Lan G, Twa MD, Song C, Feng J, Huang Y, Xu J, Qin J, An L, Wei X. In vivo corneal elastography: A topical review of challenges and opportunities. Comput Struct Biotechnol J 2023; 21:2664-2687. [PMID: 37181662 PMCID: PMC10173410 DOI: 10.1016/j.csbj.2023.04.009] [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: 02/14/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023] Open
Abstract
Clinical measurement of corneal biomechanics can aid in the early diagnosis, progression tracking, and treatment evaluation of ocular diseases. Over the past two decades, interdisciplinary collaborations between investigators in optical engineering, analytical biomechanical modeling, and clinical research has expanded our knowledge of corneal biomechanics. These advances have led to innovations in testing methods (ex vivo, and recently, in vivo) across multiple spatial and strain scales. However, in vivo measurement of corneal biomechanics remains a long-standing challenge and is currently an active area of research. Here, we review the existing and emerging approaches for in vivo corneal biomechanics evaluation, which include corneal applanation methods, such as ocular response analyzer (ORA) and corneal visualization Scheimpflug technology (Corvis ST), Brillouin microscopy, and elastography methods, and the emerging field of optical coherence elastography (OCE). We describe the fundamental concepts, analytical methods, and current clinical status for each of these methods. Finally, we discuss open questions for the current state of in vivo biomechanics assessment techniques and requirements for wider use that will further broaden our understanding of corneal biomechanics for the detection and management of ocular diseases, and improve the safety and efficacy of future clinical practice.
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Affiliation(s)
- Gongpu Lan
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Michael D Twa
- College of Optometry, University of Houston, Houston, TX 77204, United States
| | - Chengjin Song
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
| | - JinPing Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Yanping Huang
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jingjiang Xu
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jia Qin
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Lin An
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Xunbin Wei
- Biomedical Engineering Department, Peking University, Beijing 100081, China
- International Cancer Institute, Peking University, Beijing 100191, China
- Institute of Medical Technology, Peking University Health Science Center, Beijing 100191, China
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9
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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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Sun X, Qiao Y, Zhao L, Shi Z, Zhang X, Cao R, Zhou Q, Shi W. Application of Decellularized Porcine Sclera in Repairing Corneal Perforations and Lamellar Injuries. ACS Biomater Sci Eng 2022; 8:5295-5306. [PMID: 36454184 DOI: 10.1021/acsbiomaterials.2c00972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Scleras are mainly used for the treatment of glaucoma, eyelid damage, and scleral ulcers. Given that the sclera and cornea collectively constitute the complete external structure of the eyeball and both have the same tissue and cell origin, we attempted to identify scleral materials to treat lamellar and penetrating corneal injuries. Based on research in our center, antigenic components in decellularized porcine sclera (DPS) were removed using a simplified decellularization method, leaving the collagen structure and active components undamaged. DPS preserved the mechanical properties and did not significantly inhibit the proliferation and replication of human corneal epithelial cells. In vivo, the graft epithelium healed well after lamellar and penetrating scleral grafting, and the graft thickness did not change evidently. DPS can resist suture traction during scleral transplantation and maintain anterior chamber stability until day 28 post-operatively, especially in penetrating repairs. No obvious immune rejection of lamellar or penetrating scleral grafts was found 28 days after DPS transplantation. This study shows that DPS could be used as an alternative material for the emergency repair of corneal perforations and lamellar injuries, representing another application of sclera.
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Affiliation(s)
- Xiuli Sun
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Yujie Qiao
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Long Zhao
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Zhen Shi
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Xiaoyu Zhang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Rui Cao
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Eye Institute of Shandong First Medical University, Jingsi Road, Jinan 271000, China
| | - Qingjun Zhou
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, 5 Yan'erdao Road, Qingdao 266071, China
| | - Weiyun Shi
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Jingsi Road, Jinan 271000, China
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11
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Chang L, Zhang L, Cheng Z, Zhang N, Wang C, Wang Y, Liu W. Effectiveness of collagen cross-linking induced by two-photon absorption properties of a femtosecond laser in ex vivo human corneal stroma. BIOMEDICAL OPTICS EXPRESS 2022; 13:5067-5081. [PMID: 36187250 PMCID: PMC9484424 DOI: 10.1364/boe.468593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 06/16/2023]
Abstract
This study aimed to investigate the effectiveness of two-photon induced collagen cross-linking (CXL) using femtosecond lasers in human corneal stroma. An 800-nm femtosecond laser optical path for CXL was established. Corneal samples that received two-photon induced CXL and ultraviolet-A (UVA) CXL underwent uniaxial stretching experiments, proteolytic resistance assays and observation of collagen fiber structure changes. Two-photon induced CXL can achieve corneal stiffening effects comparable to UVA CXL and showed better advantages at low strains. The cornea after two-photon induced CXL exhibited high enzymatic resistance and tight collagen fiber arrangement. Two-photon induced CXL promises to be a new option for keratoconus.
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Affiliation(s)
- Le Chang
- Clinical College of Ophthalmology, Tianjin Medical University, No. 22 Meteorological Terrace Road, Heping District, Tianjin 300070, China
| | - Lin Zhang
- Clinical College of Ophthalmology, Tianjin Medical University, No. 22 Meteorological Terrace Road, Heping District, Tianjin 300070, China
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, No. 4 Gansu Road, Heping District, Tianjin 300020, China
| | - Zhenzhou Cheng
- Institute of Modern Optics, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
- Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Nan Zhang
- Institute of Modern Optics, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
- Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Congzheng Wang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, No. 22 Meteorological Terrace Road, Heping District, Tianjin 300070, China
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, No. 4 Gansu Road, Heping District, Tianjin 300020, China
| | - Weiwei Liu
- Institute of Modern Optics, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
- Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
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12
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Zhou J, Gu W, Gao Y, Wang W, Zhang F. Survival analysis of myopic regression after small incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis for low to moderate myopia. EYE AND VISION (LONDON, ENGLAND) 2022; 9:28. [PMID: 35909114 PMCID: PMC9341088 DOI: 10.1186/s40662-022-00300-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND To report the predictive factors of myopic regression in patients who had undergone small incision lenticular extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileuses (FS-LASIK) after 3-12 months of follow-up. METHODS This retrospective case series study recruited patients with a subjective sphere of - 1.00 to - 6.00 D myopia. SMILE was performed in 1629 eyes of 1629 patients with a subjective refraction spherical equivalent (SEQ) of - 4.57 ± 1.20 D and 1414 eyes of 1414 patients with a subjective SEQ of - 4.53 ± 1.26 D in FS-LASIK. Refractive outcomes were recorded at 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Predictors affecting myopic regression and other covariates were estimated with a Cox proportional hazard (Cox PH) model for the two surgical methods. RESULTS At 12 months, no significant difference was evident in the efficacy (P = 0.934), predictability (P = 0.733), or stability (P = 0.66) between FS-LASIK and SMILE. The survival rates were 83.7% in the FS-LASIK group and 88.1% in the SMILE group. Multivariate analysis by the Cox PH model revealed a similar probability of postoperative myopic regression with SMILE or FS-LASIK (P = 0.630). Predictors of myopic regression included preoperative higher-order aberration root mean square with 3 mm pupil diameter (pre-HOA-RMS3) (P = 0.004), anterior chamber depth (ACD) (P = 0.015), pre-subjective sphere (P = 0.016), corneal diameter (P = 0.016), optical zone (OZ) (P = 0.02), and predicted depth of ablation (DA) (P = 0.003). CONCLUSION SMILE and FS-LASIK had a similar risk of myopic regression for low to moderate myopia. Pre-HOA-RMS3, ACD, pre-subjective sphere, corneal diameter, OZ, and predicted DA were predictors of myopic regression.
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Affiliation(s)
- Jihong Zhou
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing Ophthalmology and Science Key Lab, Capital Medical University, No. 1 Dongjiaomin Xiang, Dongcheng District, Beijing, 100730, China
- Beijing Aier Intech Eye Hospital, Beijing, China
| | - Wei Gu
- Beijing Aier Intech Eye Hospital, Beijing, China
| | - Yan Gao
- Beijing Aier Intech Eye Hospital, Beijing, China
| | - Wenjuan Wang
- Beijing Aier Intech Eye Hospital, Beijing, China
| | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing Ophthalmology and Science Key Lab, Capital Medical University, No. 1 Dongjiaomin Xiang, Dongcheng District, Beijing, 100730, China.
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13
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Changes in Corneal Morphology and Biomechanics in Cases of Small Incision Lenticule Extraction with Prophylactic Accelerated Collagen Cross-Linking. J Ophthalmol 2022; 2022:1640249. [PMID: 35859778 PMCID: PMC9293522 DOI: 10.1155/2022/1640249] [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: 02/10/2022] [Accepted: 06/12/2022] [Indexed: 11/18/2022] Open
Abstract
Purpose To study the corneal morphology and biomechanics in cases of small incision lenticule extraction with prophylactic accelerated collagen cross-linking (SMILE Xtra). Methods This study was a retrospective study. 28 eyes of 14 patients with moderate-high risk of postoperative ectasia according to the Randleman scoring system underwent SMILE Xtra procedure. Outcome data were recorded including uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), surface regularity index (SRI), surface asymmetry index (SAI), simulated keratometry (SimK), posterior axial curvature (PAC), anterior and posterior corneal elevations (ACE and PCE), central corneal thickness (CCT), corneal resistance factor (CRF), corneal hysteresis (CH), and cornea-compensated intraocular pressure (IOPcc). The follow-up period was 12 months. Results There were 28, 26, 22, 12, and 10 eyes enrolled at postoperative 1st day and 1st, 3rd, 6th, and 12th months, respectively. The UDVA improved from 1.27 ± 0.18 logMAR preoperatively to -0.06 ± 0.04 logMAR postoperatively (P < 0.05). The MRSE improved from -5.05 ± 1.15 D preoperatively to -0.14 ± 0.30 D postoperatively (P < 0.05). SAI, SimK, PAC, PCE, and CCT all changed significantly at 1st month postoperatively (P < 0.05) and stabilized during the remainder of the follow-up (P > 0.05). There was no significant change in SRI or ACE before and after surgery (P > 0.05). CRF, CH, and IOPcc all decreased significantly at 1st month postoperatively (P < 0.05) and remained stable afterwards (P > 0.05). Conclusions The changes in the corneal morphology and biomechanics remained stable after SMILE Xtra, and there was no sign of postoperative ectasia or refractive regression. Combined with the improvement of visual and refractive results, SMILE Xtra may be a promising method for corneal refractive surgeries in patients at risk.
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14
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Zarei-Ghanavati S, Jafarpour S, Hassanzadeh S, Bakhtiari E, Daraee G, Monadi SD, Ziaei M. Changes in Corneal Biomechanical Properties After Small-Incision Lenticule Extraction and Photorefractive Keratectomy, Using a Noncontact Tonometer. Cornea 2022; 41:886-893. [PMID: 34690272 DOI: 10.1097/ico.0000000000002888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/14/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE The aim of this study was to evaluate and compare early corneal biomechanical changes after small-incision lenticule extraction (SMILE) and photorefractive keratectomy (PRK). METHODS The study comprised 74 patients eligible for refractive surgery, equally allocated to PRK (37 patients) and SMILE (37 patients). Corneal biomechanical properties were recorded and compared between the 2 groups at preoperatively and 3 months after surgery using a dynamic ultra-high-speed Scheimpflug camera equipped with a noncontact tonometer. RESULTS Both procedures significantly affected corneal biomechanical properties at 3 months after surgery. Patients in the PRK group showed significantly better results for deformation amplitude ratio (DA ratio) ( P = 0.03), maximum inverse radius (InvRadMax) ( P = 0.02), and A2 time ( P = 0.03). The mean changes in DA ratio, HC radius, InvRadMax, and Ambrosio relational thickness were significantly higher in the SMILE group in comparison with those of the PRK group (all, P < 0.05). In both groups, change in CCT was significantly correlated with changes in DA ratio and InvRadMax ( P < 0.05). CONCLUSIONSS Both SMILE and PRK refractive surgeries significantly altered corneal biomechanical properties but the changes were more prominent after SMILE.
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Affiliation(s)
- Siamak Zarei-Ghanavati
- Ophthalmology Department, Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Soheyla Jafarpour
- Ophthalmology Department, Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Samira Hassanzadeh
- Department of Optometry, Refractive Error Research Center, Paramedical College, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elham Bakhtiari
- Department of ophthalmology, Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ghazaleh Daraee
- Student Research Committee, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; and
| | - Sahar Darabi Monadi
- Student Research Committee, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; and
| | - Mohammed Ziaei
- Faculty of Medical and Health Sciences, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
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15
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16
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Song Y, Fang L, Zhu Q, Du R, Guo B, Gong J, Huang J. Biomechanical responses of the cornea after small incision lenticule extraction (SMILE) refractive surgery based on a finite element model of the human eye. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:4212-4225. [PMID: 34198433 DOI: 10.3934/mbe.2021211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
PURPOSE To investigate the biomechanical responses of the human cornea after small incision lenticule extraction (SMILE) procedures, especially their effects of SMILE surgery on stress and strain. METHODS Based on finite element analysis, a three-dimensional (3D) model of the human eye was established to simulate SMILE refractive surgery procedures. Stress and strain values were calculated by inputting the intraocular pressure (IOP). RESULTS After SMILE refractive surgery procedures, the stress and strain of the anterior and posterior corneal surfaces were significantly increased. The equivalent stress and strain on the anterior and posterior corneal surfaces increased with increasing diopter and were concentrated in the central area, whereas the values of stress and strain at the incision site on the anterior surface of the cornea were approximately 0. Compared with the anterior corneal surface, the stress and strain of the posterior surface were larger. Increasing IOP caused an approximately linear change in stress and a nonlinear increase in corneal strain. In addition, we found that the incision sizes and direction had less of an influence on stress and strain. In summary, SMILE surgery increased the equivalent stress and strain on the human cornea. CONCLUSIONS The equivalent stress and strain of the anterior and posterior human corneal surfaces increased after SMILE refractive surgery; these increases were particularly noticeable on the posterior surface of the cornea.
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Affiliation(s)
- Yinyu Song
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Lihua Fang
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Qinyue Zhu
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Ruirui Du
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Binhui Guo
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Jiahui Gong
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Jixia Huang
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
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Wilson A, Marshall J. A review of corneal biomechanics: Mechanisms for measurement and the implications for refractive surgery. Indian J Ophthalmol 2021; 68:2679-2690. [PMID: 33229643 PMCID: PMC7856929 DOI: 10.4103/ijo.ijo_2146_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Detailed clinical assessment of corneal biomechanics has the potential to revolutionize the ophthalmic industry through enabling quicker and more proficient diagnosis of corneal disease, safer and more effective surgical treatments, and the provision of customized and optimized care. Despite these wide-ranging benefits, and an outstanding clinical need, the provision of technology capable of the assessment of corneal biomechanics in the clinic is still in its infancy. While laboratory-based technologies have progressed significantly over the past decade, there remain significant gaps in our knowledge regarding corneal biomechanics and how they relate to shape and function, and how they change in disease and after surgical intervention. Here, we discuss the importance, relevance, and challenges associated with the assessment of corneal biomechanics and review the techniques currently available and underdevelopment in both the laboratory and the clinic.
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Affiliation(s)
- Abby Wilson
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
| | - John Marshall
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
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Abstract
The emergence of SMILE in the last decade has provided an alternative to LASIK for patients considering cornea laser refractive surgery. SMILE offers a novel approach using the femtosecond laser to create an intrastromal lenticule that can be removed through a small three to four millimeter incision.The purpose of this study is to review the recent literature on popular SMILE claims - reduced iatrogenic dry eye, better recovery of corneal sensation, and a biomechanically stronger cornea - summarize the published outcomes, and determine which claims are myths versus realities.SMILE is still in its infancy as a refractive technique in the US after recent USFDA approval for its treatment of myopia astigmatism in October 2018. Future randomized controlled studies are needed to compare its outcomes to LASIK, which has well-documented good visual outcomes, rapid postoperative recovery, and good safety profile.
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Affiliation(s)
- Grace Huang
- Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.,Boston Eye Group, Brookline, MA, USA
| | - Samir Melki
- Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.,Boston Eye Group, Brookline, MA, USA
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Hu Y, Huang Y, Chen Y, Ye C, Wei W, Feng Y, Mi S. Study on patterned photodynamic cross-linking for keratoconus. Exp Eye Res 2021; 204:108450. [PMID: 33497690 DOI: 10.1016/j.exer.2021.108450] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 12/30/2020] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
PURPOSE This study examined the patterned treatment of corneal collagen cross-linking (CXL) for keratoconus to reduce the complications caused by ultraviolet (UV) irradiation. By modifying the method of UV irradiation during the cross-linking process, cross-linking with a special structure is achieved, and the cross-linking effect is analyzed and compared to that of traditional cross-linking. By constructing an animal model of keratoconus, the process and effect of corneal cross-linking can be investigated more fundamentally. These studies provide valuable references for future cross-linking precision improvement and specialization. METHOD By injecting exogenous collagenase into the corneal stroma of rabbits, the balance between collagenase and collagenase inhibitor in the corneal stroma was disrupted, the collagen fiber structure of the cornea was broken to simulate the pathogenesis of keratoconus, and an animal model of keratoconus was thus constructed. Two custom cross-linking patterns were designed with reference to the cable dome structure, and these two special patterns were irradiated and cross-linked by a DMD chip. The cross-linking effect was evaluated by optical coherence tomography (OCT), corneal topography and corneal biaxial tensile tests. The experimental rabbits were divided into four groups: group A, cross-linking of the bird's nest structure; group B, cross-linking of the honeycomb structure; group C, cross-linking of the traditional spot structure; and group D, normal (without modeling and cross-linking). RESULT Following collagenase treatment, the collagen fiber structure of the rabbit cornea was destroyed, the central thickness of the cornea was reduced, the mechanical properties of the cornea were weakened, and no keratitis, ulcers or haze occurred. After the three cross-linking treatments, the morphology of the cornea improved, the density of the stromal layer increased, and the mechanical properties were enhanced. For the improvement of keratoconus mechanical properties, the average relative difference (Δ) of the four outcome measures was 61.98% for bird's nest cross-linking versus keratoconus (Wilcoxon rank sum test, P = 0.024), 16.13% for honeycomb cross-linking versus keratoconus (Wilcoxon rank sum test, P = 0.025), and 21.07% for traditional spot cross-linking versus keratoconus (Wilcoxon rank sum test, P = 0.014). All these differences are statistically significant. CONCLUSION All three methods of cross-linking can improve the morphology and tissue structure of keratoconus and significantly improve the biomechanical properties of the cornea. Among them, the corneal cross-linking of the bird's nest structure attains the best biomechanical properties, followed by the corneal cross-linking of the traditional spot structure and of the honeycomb structure. This suggests that similar or better cross-linking effects can be achieved by designing custom structures with less UV exposure. This provides a direction for future research on better and more accurate pattern cross-linking treatments.
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Affiliation(s)
- Yingbing Hu
- Open FIESTA Center, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China; Biomanufacturing Engineering Laboratory, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China
| | - Yu Huang
- Biomanufacturing Engineering Laboratory, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China
| | - Yun Chen
- Open FIESTA Center, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China; Biomanufacturing Engineering Laboratory, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China
| | - Cheng Ye
- Open FIESTA Center, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China; Biomanufacturing Engineering Laboratory, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China
| | - Wei Wei
- Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Yun Feng
- Ophthalmology Department, Peking University Third Hospital, China
| | - Shengli Mi
- Open FIESTA Center, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China; Biomanufacturing Engineering Laboratory, International Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China; Department of Mechanical Engineering, Biomanufacturing Center, Tsinghua University, Beijing, PR China.
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20
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Asif MI, Bafna RK, Mehta JS, Reddy J, Titiyal JS, Maharana PK, Sharma N. Complications of small incision lenticule extraction. Indian J Ophthalmol 2020; 68:2711-2722. [PMID: 33229647 PMCID: PMC7856979 DOI: 10.4103/ijo.ijo_3258_20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The procedure of small incision lenticule extraction (SMILE) was introduced in 2011, and since then there has been an increase in the number of cases undergoing this procedure worldwide. The surgery has a learning curve and may be associated with problems in the intraoperative and postoperative periods. The intraoperative problems during SMILE surgery include the loss of suction, the occurrence of altered or irregular opaque bubble layer and black spots, difficulty in lenticular dissection and extraction, cap perforation, incision-related problems, and decentered ablation. Most of the postoperative problems are similar as in other laser refractive procedures, but with decreased incidence. The identification of risk factors, clinical features, and management of complications of SMILE help to obtain optimum refractive outcomes.
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Affiliation(s)
- Mohamed Ibrahime Asif
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Rahul Kumar Bafna
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Jodhbir Singh Mehta
- Singapore Eye Research Institute; Singapore National Eye Centre, 168751; Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Medical School, Singapore
| | - Jagadesh Reddy
- Cataract and Refractive Services, Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Jeewan Singh Titiyal
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Prafulla K Maharana
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Namrata Sharma
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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21
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Liu T, Shen M, Li H, Zhang Y, Mu B, Zhao X, Wang Y. Changes and quantitative characterization of hyper-viscoelastic biomechanical properties for young corneal stroma after standard corneal cross-linking treatment with different ultraviolet-A energies. Acta Biomater 2020; 113:438-451. [PMID: 32525050 DOI: 10.1016/j.actbio.2020.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/30/2020] [Accepted: 06/02/2020] [Indexed: 12/27/2022]
Abstract
Corneal collagen cross-linking (CXL) treatment can restore vision in patients suffering from keratoconus and corneal injury, by improving the mechanical properties of the cornea. The correlation between ultraviolet-A (UVA) irradiant energies of standard CXL (SCXL) and corneal visco-hyperelastic mechanical behavior remains unknown. In this study, SCXL with four different UVA irradiant energy doses (0-5.4 J/cm2) were administered as part of quantitative treatments of corneal stromal lenticules extracted from young myopic patients via small incision lenticule extraction (SMILE) corneal refractive surgery. Double-strip samples with symmetric geometries were cut simultaneously for SCXL treatment and non-treated control. First, 40 pairs of strips were loaded to failure to assess the mechanical parameters of the material. Then, another 40 pairs were tested using a special uniaxial tensile test including quasi-static loading-unloading, instantaneous loading, and stress relaxation, to determine the visco-hyperelastic mechanical behavior. Upon combining the collagen fibril crimping constitutive model with the quasi-linear viscoelastic model, it was observed that with increasing UVA energy dose, the corneal strength and hyperelastic stiffness were significantly enhanced, while the maximum stretch and viscosity of the cornea were significantly reduced. Considering the quantitative analysis of SCXL and the rehabilitation prediction of keratoconus treatment, the results clarify the biomechanical behavior of human corneal stroma in SCXL clinical surgery. STATEMENT OF SIGNIFICANCE: This study quantitatively analyzes the improvement in the biomechanical properties of young central corneal stroma, due to SCXL treatment with different energies. Furthermore, the correlation between the hyper-viscoelastic mechanical parameters and UVA irradiant energy doses of SCXL are clarified. The contribution of this study fills the knowledge gap of the CXL on corneal biomechanics. It can not only clarify this mechanism better but also assist with guiding SCXL surgery for individualized patient corneas.
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Affiliation(s)
- Taiwei Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350 China; Department of Engineering Mechanics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Min Shen
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350 China.
| | - Hongxun Li
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Yan Zhang
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Bokun Mu
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Xinheng Zhao
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Yan Wang
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
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22
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Soundarya B, Sachdev GS, Ramamurthy S, Dandapani R. Ectasia after keratorefractive surgery: Analysis of risk factors and treatment outcomes in the Indian population. Indian J Ophthalmol 2020; 68:1028-1031. [PMID: 32461422 PMCID: PMC7508091 DOI: 10.4103/ijo.ijo_1580_19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose: To analyze the risk factors in eyes developing ectasia following keratorefractive procedures. In addition, the study assessed visual outcomes following various treatment modalities for ectasia. Methods: In this retrospective study, data of patients who underwent keratorefractive procedures, presenting to the refractive services of a tertiary eye care hospital in South India between January 2016 and May 2019 was analyzed. Of these, the eyes that developed ectasia were noted and the possible risk factors were determined. Visual outcomes following treatment with corneal collagen crosslinking (CXL) with or without intracorneal ring segment implantation (ICRS) or topography-guided corneal ablation (T-PRK) were analyzed. Results: Forty eyes of 26 patients developed ectasia following keratorefractive procedures, with a mean interval of 73.1± 45.4 months between primary procedure and ectasia development. Of these, 14 patients had bilateral presentation. Identifiable risk factors included ablation depth >75 μm (59.25%), percentage of tissue altered (PTA) >40% (48.14%), residual stromal bed <300 μm (22.22%), mean refractive spherical equivalent >8 D (25.92%), inferior–superior (I–S) asymmetry >1.4D (7.40%), central corneal thickness (CCT) <500 μm (7.40%), Belin Ambrosio Display (BAD) >2.5 (7.40%), posterior float elevation maximum ≥18 μm (3.70%), and pellucid marginal degeneration (PMD; 3.70%). Conclusion: Our study shows that only 70% of the eyes demonstrated an identifiable risk factor for the development of ectasia. Ablation depth of >75 μm and the PTA >40% were the most common risk factors. Treatment following CXL with ICRS or T-PRK demonstrated significantly better visual outcomes in comparison with CXL alone.
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Affiliation(s)
- B Soundarya
- Refractive Services, The Eye Foundation, Coimbatore, Tamil Nadu, India
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23
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Characterization of hyperelastic mechanical properties for youth corneal anterior central stroma based on collagen fibril crimping constitutive model. J Mech Behav Biomed Mater 2020; 103:103575. [DOI: 10.1016/j.jmbbm.2019.103575] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 11/03/2019] [Accepted: 11/29/2019] [Indexed: 11/19/2022]
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24
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Changes in corneal biomechanics during small-incision lenticule extraction (SMILE) and femtosecond-assisted laser in situ keratomileusis (FS-LASIK). Lasers Med Sci 2019; 35:599-609. [DOI: 10.1007/s10103-019-02854-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
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25
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Kim TI, Alió Del Barrio JL, Wilkins M, Cochener B, Ang M. Refractive surgery. Lancet 2019; 393:2085-2098. [PMID: 31106754 DOI: 10.1016/s0140-6736(18)33209-4] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/29/2018] [Accepted: 12/11/2018] [Indexed: 01/19/2023]
Abstract
Refractive surgery has evolved beyond laser refractive techniques over the past decade. Laser refractive surgery procedures (such as laser in-situ keratomileusis), surface ablation techniques (such as laser epithelial keratomileusis), and photorefractive keratectomy have now been established as fairly safe procedures that produce excellent visual outcomes for patients with low-to-moderate amounts of ametropia. Additionally, a broader selection of options are now available to treat a wider range of refractive errors. Small incision lenticule extraction uses a femtosecond laser to shape a refractive lenticule, which is removed through a small wound. The potential advantages of this procedure include greater tectonic strength and less dry eye. In the future, intracorneal implants could be used to treat hyperopia or presbyopia. Phakic intraocular implants and refractive lens exchange might be useful options in carefully selected patients for correcting high degrees of ametropia. Thus, physicians are now able to provide patients with the appropriate refractive corrective option based on the individual's risk-benefit profile.
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Affiliation(s)
- Tae-Im Kim
- Department of Ophthalmology, The Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Jorge L Alió Del Barrio
- Cornea, Cataract and Refractive Surgery Unit, Research & Development Department VISSUM Innovation Alicante, Alicante, Spain; Division of Ophthalmology, School of Medicine, Universidad Miguel Hernández, Alicante, Spain
| | - Mark Wilkins
- Department of Ophthalmology, Moorfields Eye Hospital, London, UK
| | - Beatrice Cochener
- Department of Ophthalmology, University Hospital Morvan, Brest, France
| | - Marcus Ang
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore; Department of Ophthalmology and Visual Science, Duke-NUS Graduate Medical School, Singapore.
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Spiru B, Kling S, Hafezi F, Sekundo W. Biomechanical Properties of Human Cornea Tested by Two-Dimensional Extensiometry Ex Vivo in Fellow Eyes: Femtosecond Laser-Assisted LASIK Versus SMILE. J Refract Surg 2018; 34:419-423. [PMID: 29889296 DOI: 10.3928/1081597x-20180402-05] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 04/02/2018] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the biomechanical properties of the ex vivo human cornea after flap-based versus cap-based laser refractive surgery in the same donor. METHODS In this experimental study, 11 pairs of human corneas unsuitable for transplantation were equally divided into two groups. Corneas from the right eye were treated with femtosecond laser-assisted LASIK (FSLASIK) and corneas from the left eye with small incision lenticule extraction (SMILE). Pachymetry was measured in each eye directly before laser refractive surgery. All corneas were subjected to a refractive correction of -10.00 diopters (D) sphere and -0.75 D cylinder at 0° with a 7-mm zone, using either a 110-μm flap (FS-LASIK) or 130-μm cap (SMILE). For two-dimensional biomechanical measurements, corneoscleral buttons underwent two testing cycles (preconditioning stress-strain curve from 0.03 to 9.0 N and stress-relaxation at 9.0 N during 120 sec) to analyze the elastic and viscoelastic material properties. The effective elastic modulus was calculated. Statistical analysis was performed with a confidence interval of 95%. RESULTS In stress-strain measurements, the effective elastic modulus was 1.47 times higher (P = .003) after SMILE (median = 8.22 [interquartile range = 4.76] MPa) compared to FS-LASIK (median = 5.59 [inter-quartile range = 2.77] MPa). The effect size was large (r = 0.83). No significant differences (P = .658) were observed among stress-relaxation measurements, with a mean remaining stress of 181 ± 31 kPa after SMILE and 177 ± 26 kPa after FS-LASIK after relaxation. CONCLUSIONS Compared to a flap-based procedure such as FS-LASIK, the SMILE technique can be considered superior in terms of biomechanical stability, when measured experimentally in ex vivo human fellow eye corneas. [J Refract Surg. 2018;34(6):419-423.].
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27
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Vanathi M. Advances in Cornea. Open Ophthalmol J 2018; 12:130-133. [PMID: 30123377 PMCID: PMC6062899 DOI: 10.2174/1874364101812010130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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28
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Ge Q, Cui C, Wang J, Mu G. Combined transepithelial phototherapeutic keratectomy and corneal collagen cross-linking for corneal ectasia after small-incision lenticule extraction-preoperative and 3-year postoperative results: a case report. BMC Ophthalmol 2018; 18:175. [PMID: 30016942 PMCID: PMC6050682 DOI: 10.1186/s12886-018-0849-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 07/12/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Corneal ectasia after small-incision lenticule extraction (SMILE) is uncommon. To our knowledge, this is the first report of 3-year results of combined phototherapeutic keratectomy (PTK) and corneal collagen cross-linking (CXL) for corneal ectasia after SMILE. CASE PRESENTATION Herein, we describe a case of prominent corneal ectasia after SMILE treated with PTK combined with CXL 3 years ago. After surgery, maximum corneal keratometry, mean corneal keratometry, spherical equivalent and uncorrected distance visual acuity were significantly improved at follow-up intervals. CONCLUSIONS Transepithelial PTK combined with CXL for corneal ectasia after SMILE may be an effective and safe treatment in the long term.
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Affiliation(s)
- Qingman Ge
- Department of Ophthalmology, Shandong Provincial Hospital affiliated to Shandong University, HuaiYin District, Jing 5 Wei 6 Road no. 324, Jinan, China. .,Lunan Eye Hospital, Lanshan District, Yucai Road no. 109, Linyi, China.
| | - Chuanbo Cui
- Department of Ophthalmology, Shandong Medical College, Lanshan District, Jucai Road no. 6, Linyi, China
| | - Jing Wang
- Lunan Eye Hospital, Lanshan District, Yucai Road no. 109, Linyi, China
| | - Guoying Mu
- Department of Ophthalmology, Shandong Provincial Hospital affiliated to Shandong University, HuaiYin District, Jing 5 Wei 6 Road no. 324, Jinan, China
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