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Wang Z, Li M, Ji H, Chen H, Sang A, Cheng X, Li J, Yu Y. Comparison of risk factors for OBL in FS-LASIK and SMILE correction for myopia and myopia astigmatism. Graefes Arch Clin Exp Ophthalmol 2024; 262:1925-1931. [PMID: 38091059 DOI: 10.1007/s00417-023-06336-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/26/2023] [Accepted: 11/30/2023] [Indexed: 05/22/2024] Open
Abstract
BACKGROUND To find out the incidence and risk factors of opaque bubble layer (OBL) in eyes with myopia and myopic astigmatism following femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). METHODS A total of 1076 eyes from 569 patients who had FS-LASIK or SMILE were included in the retrospective research. For each kind of surgery, eyes were separated into two groups: "OBL" groups and "no OBL" groups. In the FS-LASIK group, eyes that developed OBL were split into "hard OBL" and "soft OBL" groups. The incidence and size of OBL were analyzed after watching the surgical procedure videotaped during the operation and taking screenshots. Surgical parameters, including sphere, cylinder, keratometry, corneal thickness, flap thickness, cap thickness, lenticule thickness, and visual acuity, were compared. RESULTS In the FS-LASIK surgery, the incidence of OBL was 63.2% (347 eyes). A thicker central corneal thickness (CCT) was the only independent risk factor affecting the OBL area (β = 0.126, P = 0.019). One hundred and thirty of these eyes had hard OBL, and the flap thickness of these eyes was thinner than that of those with soft OBL (P = 0.027). In the SMILE group, 26.6% (140 eyes) developed OBL. A higher flat keratometry (K) and a thicker residual stromal thickness (RST) were risk factors affecting the OBL area (β = 0.195, P = 0.024; β = 0.281, P = 0.001). CONCLUSION The incidence of OBL differs between the FS-LASIK surgery and the SMILE surgery. There are differences in the factors influencing OBL between the two surgeries.
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Affiliation(s)
- Zichen Wang
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Mingrui Li
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Haixia Ji
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Hui Chen
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Aimin Sang
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Xinliang Cheng
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China
| | - Jun Li
- Department of Dermatology, Nantong First People's Hospital, Second Affiliated Hospital of Nantong University, Nantong, 226001, China
| | - Ying Yu
- Eye Institute, Affiliated Hospital of Nantong University, Medical School of Nantong University, No. 20, Xisi Road, Nantong City, 226001, Jiangsu Province, China.
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Song Y, Deng S, Lyv X, Xu Y, Zhang F, Guo N. Corneal subbasal nerve plexus reinnervation and stromal cell morphology with different cap thicknesses in small incision lenticule extraction. EYE AND VISION (LONDON, ENGLAND) 2024; 11:15. [PMID: 38584290 PMCID: PMC11000360 DOI: 10.1186/s40662-024-00381-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 03/10/2024] [Indexed: 04/09/2024]
Abstract
PURPOSE The corneal cap thickness is a vital parameter designed in small incision lenticule extraction (SMILE). The purpose was to investigate the changes in corneal subbasal nerve plexus (SNP) and stromal cells with different cap thicknesses and evaluate the optimized design for the surgery. METHODS In this prospective, comparative, non-randomized study, a total of 108 eyes of 54 patients who underwent SMILE were allocated into three groups with different corneal cap thicknesses (110 μm, 120 μm or 130 μm group). The SNP and stromal cell morphological changes obtained from in vivo corneal confocal microscopy (IVCCM) along with their refractive outcomes were collected at 1 week, 1 month, 3 months and 6 months postoperatively. One-way analysis of variance (ANOVA) was used to compare the parameters among the three groups. RESULTS The SNPs in the three groups all decreased after surgery and revealed a gradual increasing trend during the 6-month follow-up. The values of the quantitative nerve metrics were significantly lower in the 110 μm group than in the 120 μm and 130 μm groups, especially at 1 week postoperatively. No difference was detected between the 120 μm and 130 μm groups at any time point. Both Langerhans cells and keratocytes were activated after surgery, and the activation was alleviated during the follow-up. CONCLUSIONS The SMILE surgeries with 110 μm, 120 μm or 130 μm cap thickness design achieved good efficacy, safety, accuracy and stability for moderate to high myopic correction while the thicker corneal cap was more beneficial for corneal nerve regeneration.
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Affiliation(s)
- Yanzheng Song
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Shijing Deng
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Xiaotong Lyv
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Yushan Xu
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Fengju Zhang
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China.
| | - Ning Guo
- Beijing Ophthalmology and Visual Sciences Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China.
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Zarei-Ghanavati S, Jafarzadeh SV, Es'haghi A, Kiarudi MY, Hassanzadeh S, Ziaei M. Comparison of 110- and 145-µm Small-Incision Lenticule Extraction Cap Thickness: A Randomized Contralateral Eye Study. Cornea 2024; 43:154-158. [PMID: 37186807 DOI: 10.1097/ico.0000000000003294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/13/2023] [Indexed: 05/17/2023]
Abstract
PURPOSE To investigate the visual, refractive, and biomechanical outcomes of small incision lenticule extraction (SMILE) with two different cap thicknesses. METHODS Thirty-four patients were included in this prospective, randomized, contralateral eye study. Subjects were randomized to receive SMILE surgery with a 110-m cap thickness in one eye and 145-µm cap thickness in the fellow eye. Uncorrected and corrected distance visual acuity, contrast sensitivity (CS), total higherorder aberrations (THOAs) and corneal biomechanical properties were compared 3 months after surgery. RESULTS Postoperative refractive and visual outcomes, CS and THOAs were similar between the two groups ( P > 0.05 for all parameters). At 3 months postoperatively, there was a significant difference in Corvis ST Biomechanical Index (CBI); stiffness parameter at first applanation (SP A1), and Integrated Radius between the two groups (all P < 0.05). CONCLUSIONS Eyes with thicker SMILE corneal caps showed no advantage regarding visual acuity, CS and THOAs over eyes with thinner caps. However, higher cap thickness may result in better corneal biomechanical properties postoperatively.
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Affiliation(s)
| | | | - Acieh Es'haghi
- Eye Research Center, Five Senses Health Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | | | - Samira Hassanzadeh
- Refractive Error Research Center, Paramedical College, Mashhad University of Medical Sciences, Mashhad, Iran; and
| | - Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Lv X, Zhang F, Song Y, Zhai C, Guo N, Lai L, Xu Y. Corneal biomechanical characteristics following small incision lenticule extraction for myopia and astigmatism with 3 different cap thicknesses. BMC Ophthalmol 2023; 23:42. [PMID: 36717828 PMCID: PMC9885585 DOI: 10.1186/s12886-023-02786-8] [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: 10/19/2022] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND The design of cap thickness for small incision lenticule extraction (SMILE) plays a role in post-laser vision correction (post-LVC) corneal biomechanics. This study aimed to compare the corneal biomechanical characteristics following SMILE with different cap thicknesses of 110 μm, 120 μm, and 130 μm for myopia and myopic astigmatism correction. METHODS Seventy-five patients (146 eyes) who underwent SMILE with designed cap thickness of 110 μm, 120 μm, and 130 μm were recruited at the Eye Center of Beijing Tongren Hospital between August 2020 and November 2021. Visual acuity, refraction, and corneal biomechanical parameters were measured preoperatively, 1 week and 1, 3, 6 months postoperatively. One-way analysis of variances (ANOVA) with Bonferroni correction or Kruskal-Wallis test was performed to compare the parameters among different groups. Repeated-measures analysis of variance with Bonferroni correction or Friedman test was applied for comparing the parameters within different follow-up times. RESULTS Uncorrected distance visual acuity of 110-μm group was better only at 1-week and 1-month postoperatively (P = 0.012, 0.037). There were no significant differences in spherical equivalent, nor in Corvis biomechanical index-laser vision correction (CBI-LVC). All the parameters reached stability at 3-month postoperatively. Integrated radius (IR) and deformation amplitude ratio 2 mm (DA ratio 2 mm) in 120-μm and 130-μm groups were higher than 110-μm group at 1-month postoperatively (P = 0.019, 0.002). So was Ambrósio relational thickness (ARTh) at 6-month postoperatively (P = 0.011). Stiffness parameter at applanation A1 (SP-A1), stress-strain index (SSI), biomechanically corrected intraocular pressure (bIOP) and central corneal thickness (CCT) were highest in 130-μm group, followed by 120-μm group, then 110-μm group at 3-month (P<0.001, P = 0.030, P = 0.027, P = 0.008) and 6-month (P<0.001, P = 0.002, P = 0.0023, P = 0.001) postoperatively. CONCLUSIONS The corneal stiffness following SMILE was greatest with 130-μm cap, followed by 120-μm cap, then 110-μm cap. 130-μm cap might have advantages in terms of corneal biomechanics and retreatment option. The SMILE-designed protocol should be customized in practice.
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Affiliation(s)
- Xiaotong Lv
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Fengju Zhang
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Yanzheng Song
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Changbin Zhai
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Ning Guo
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Lingbo Lai
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Yushan Xu
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
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Han T, Shi W, Chen Y, Shen Y, Xu Y, Zhou X. Predictive models for IOPs measured with NCT, GAT, and ORA among patients undergoing SMILE. Front Bioeng Biotechnol 2022; 10:1030458. [PMID: 36532578 PMCID: PMC9751611 DOI: 10.3389/fbioe.2022.1030458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/18/2022] [Indexed: 09/08/2023] Open
Abstract
Purpose: To develop predictive models for the intraocular pressure (IOP) of patients undergoing small incision lenticule extraction (SMILE) procedures, measured with a noncontact tonometer (NCT), Goldmann applanation tonometry (GAT), and an ocular response analyzer (ORA). Methods: In this prospective study, a total of 104 eyes (-6.23 ± 2.06 diopters) of 52 patients (24.38 ± 4.76 years) undergoing SMILE procedures were included. The intraocular pressure was measured (IOPNCT with NCT, IOPGAT with GAT, and IOPcc and IOPg with ORA) before surgery and at postoperative 6 months. Information on age, preoperative and attempted spherical equivalent (SE), ablation depth, preoperative values and postoperative changes in central corneal thickness (CCT), K1, K2, Km, corneal hysteresis (CH) and corneal resistance factor (CRF) values was collected in order to predict IOPs. Results: All surgeries were uneventful. At postoperative 6 months, the efficacy and safety index were 1.04 ± 0.15 and 1.08 ± 0.18, respectively. Significant decreases were detected in postoperative IOPNCT, IOPGAT, IOPcc, and IOPg compared to preoperative values (all p < 0.001). No relationship was found between any IOP and ablation depth, attempted SE, and preoperative SE, as well as CCTdifference (all p > 0.05). Predictive models for IOPs were constructed to predict preoperative values, and R 2 values were 67.5% (IOPNCT), 64.5% (IOPGAT), 78.7% (IOPcc), and 82.0% (IOPg). The prediction band of IOPNCT and IOPGAT was 7.4-15.1 mmHg and 8-16 mmHg, respectively. Conclusion: Predictive models for IOP measurements after SMILE procedures can be helpful in clinical practice.
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Affiliation(s)
- Tian Han
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Wanru Shi
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yingjun Chen
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yang Shen
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Ye Xu
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Xingtao Zhou
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia Fudan University, Shanghai, China
- Research Center of Ophthalmology and Optometry Shanghai, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
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Evaluation of morphological features: femtosecond-LASIK flap vs. SMILE cap, and the effects on corneal higher-order aberrations. Graefes Arch Clin Exp Ophthalmol 2022; 260:3993-4003. [PMID: 36166075 DOI: 10.1007/s00417-022-05841-0] [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: 04/25/2022] [Revised: 08/14/2022] [Accepted: 09/20/2022] [Indexed: 11/04/2022] Open
Abstract
PURPOSE The aim of this study is to evaluate morphological features of corneal flap/cap and the correlations with corneal higher-order aberrations (HOAs) changes after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). METHODS This was a retrospective study. Pre- and postoperative (1 and 3 months) corneal HOAs were assessed with Pentacam HR. The corneal flap/cap thickness at 32 points (± 1.5 mm, ± 2 mm, ± 2.5 mm, and ± 3 mm from the corneal vertex on meridian 0°/45°/90°/135°) were measured using anterior segment optical coherence tomography at 3 months postoperatively. Morphological features of corneal flap/cap including predictability (P), uniformity (U), and symmetry (S) were calculated and used for correlation analysis with corneal HOAs changes. RESULTS Eighty-six eyes (44 patients) and ninety-six eyes (50 patients) were involved in FS-LASIK and SMILE groups, respectively. Significant thicker corneal flap/cap than the predicted was observed at each measuring point and meridian in both groups (difference > 2.225 μm, the within-subject standard deviation over 6-mm optical zone). There was no statistically significant difference in predictability of corneal flap/cap thickness, while U6 mm (P < .0001), U0 (P < .001), U45 (P = .002), U90 (P < .0001), U135 (P = .004), S6 mm (P < .0001), S0 (P < .001), and S90 (P < .0001) over 6 mm zone were less in SMILE than in FS-LASIK. The changes of corneal tHOAs, Z (3, - 1), Z (3, 1), and SA were significantly correlated with morphological features of corneal flap/cap. CONCLUSION Both FS-LASIK and SMILE had good predictability in flap or cap thickness, while the uniformity and symmetry of SMILE cap were better than FS-LASIK flap. The quality of flap/cap was closely associated with the changes of corneal HOAs.
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Liang S, Ji S, Liu X, Chen M, Lei Y, Hou J, Li M, Zou H, Peng Y, Ma Z, Liu Y, Jhanji V, Wang Y. Applying Information Gain to Explore Factors Affecting Small-Incision Lenticule Extraction: A Multicenter Retrospective Study. Front Med (Lausanne) 2022; 9:837092. [PMID: 35592861 PMCID: PMC9110865 DOI: 10.3389/fmed.2022.837092] [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: 12/16/2021] [Accepted: 03/28/2022] [Indexed: 11/17/2022] Open
Abstract
Purpose This retrospective study aimed to identify the key factors influencing postoperative refraction after small-incision lenticule extraction (SMILE) using information gain. Methods This study comprised 2,350 eyes of 1,200 patients who underwent SMILE using a Visumax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) in three ophthalmic centers: Tianjin Eye Hospital (center A), Jinan Mingshui Eye Hospital (center B), and Qingdao Eye Hospital (center C). Anterior segment features, including corneal curvature and central corneal thickness (CCT), were obtained from Pentacam HR (Oculus, Wetzlar, Germany). Information gain was calculated to analyze the importance of features affecting postoperative refraction. Results Preoperative and postoperative mean spherical equivalent (SE) refraction were −5.00 (−6.13, −3.88) D and 0.00 (−0.25, 0.13) D, respectively. None of the patients lost more than two lines of corrected distance visual acuity. The safety index was 1.32 ± 0.24, 1.03 ± 0.08, and 1.13 ± 0.16 in centers A, B, and C, respectively. The efficacy index was 1.31 ± 0.25, 1.02 ± 0.08, and 1.13 ± 0.17 in centers A, B, and C, respectively. At least 95% of the eyes were within ±1.00 D of the attempted correction. Postoperative refraction was related to preoperative spherical diopter refraction (r = 0.369, p < 0.001), preoperative SE (r = 0.364, p < 0.001), maximum lenticule thickness (r = −0.311, p < 0.001), preoperative uncorrected distance visual acuity (r = 0.164, p < 0.001), residual stromal thickness (r = 0.139, p < 0.001), preoperative mean anterior corneal curvature (r = −0.127, p < 0.001), preoperative flattest anterior corneal curvature (r = −0.122, p < 0.001), nomogram (r = −0.100, p < 0.001) and preoperative CCT (r = −0.058, p = 0.005). Conclusions SMILE was considered a safe and effective procedure for correcting myopia. Based on information gain, postoperative refraction was influenced by preoperative mean anterior corneal curvature, CCT, refraction, and residual stromal thickness.
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Affiliation(s)
- Shuang Liang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Shufan Ji
- School of Computer Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China
| | - Xiao Liu
- School of Computer Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China
| | - Min Chen
- Qingdao Eye Hospital, Shandong First Medical University, Qingdao, China
| | - Yulin Lei
- Jinan Mingshui Eye Hospital, Jinan, China
| | - Jie Hou
- Jinan Mingshui Eye Hospital, Jinan, China
| | - Mengdi Li
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Haohan Zou
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yusu Peng
- Qingdao Eye Hospital, Shandong First Medical University, Qingdao, China
| | - Zhixing Ma
- Jinan Mingshui Eye Hospital, Jinan, China
| | - Yuanyuan Liu
- Department of Health Statistics, College of Public Health, Tianjin Medical University, Tianjin, China
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
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Comparison of visual outcomes between 120-µm and 140-µm cap thicknesses 12 months after small incision lenticule extraction. Lasers Med Sci 2022; 37:2667-2673. [PMID: 35217941 DOI: 10.1007/s10103-022-03534-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 02/21/2022] [Indexed: 10/19/2022]
Abstract
To compare visual and refractive outcomes as well as changes in high-order aberrations in patients with 120- versus 140-µm cap thicknesses 12 months after small incision lenticule extraction. Ninety-four patients were randomized to receive small incision lenticule extraction with either a 120-µm cap thickness (n = 47) or a 140-µm cap thickness (n = 47) to treat myopia or myopic astigmatism, if not both. In an analysis of right eyes only during the 12-month follow-up period, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive outcomes, and high-order aberrations were evaluated. The distribution of patients by age and sex between the groups did not differ significantly (P = .803 and P = .680, respectively). CDVA, spherical and cylindrical refraction, and changes in total high-order aberration, spherical aberration, coma, and trefoil were similar between the groups at 6 and 12 months, postoperatively. However, UDVA was statistically significantly higher in patients with 140-μm cap thicknesses than with 120-μm cap thicknesses at 6 and 12 months postoperatively (P < .001 and P < .001, respectively). Patients with 140-µm cap thickness showed greater improvement in UDVA than ones with 120-µm cap thickness at 12-month follow-up (P = .005). Both 120- and 140-μm cap thicknesses in small incision lenticule extraction were safe and effective thicknesses for correcting myopia or myopic astigmatism. The patients with 140-μm cap thickness had better improvement in UDVA after 12-month follow-up compared to patients with 120-μm cap thickness.
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Liang C, Zhang Y, He Y, Wang S. Research Progress on Morphological Changes and Surgery-related Parameters of Corneal Cap in Small Incision Lenticule Extraction. Ophthalmic Res 2021; 65:4-13. [PMID: 34670218 DOI: 10.1159/000520241] [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: 06/11/2021] [Accepted: 10/10/2021] [Indexed: 11/19/2022]
Abstract
Small incision lenticule extraction (SMILE) is an "all-in-one" surgical method for refractive correction. An advantage of the SMILE over traditional surgery is that it depends on the corneal cap's design. This review discusses the morphological evaluation of the corneal cap, selection of the corneal cap with different thickness and diameters, influence of the corneal cap design on retreatment, and management of corneal cap-related complications. The following points should be recognized to define the correct morphology and design of the operation-related parameters of the corneal cap during SMILE: (1) the thickness and diameter of the corneal cap are predictable and influence postoperative visual quality, (2) the change in anterior surface curvature of the corneal cap should be considered in the design of nomogram value, (3) for patients with moderate myopic correction, early visual quality is better with a 6.9-mm than with a 7.5-mm diameter corneal cap, (4) there is no significant difference in visual quality or biomechanics among corneal caps with different thickness; (5) primary corneal cap thickness plays an important role in the SMILE retreatment, (6) a 7.78-mm diameter corneal cap has a greater risk of suction loss than a 7.60-mm diameter corneal cap, (6) if suction loss occurs when lenticular scanning exceeds 10%, then SMILE can be continued by changing corneal cap thickness, (7) preventive collagen cross-linking with SMILE caps are 90-120 μm thick and 7-7.8 mm in diameter, and (8) properly treating SMILE-related complications ensures better postoperative results. The data presented herein shall deepen the understanding of the importance of the corneal cap during SMILE and provide diversified analysis for personalized operational design of corneal cap parameters.
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Affiliation(s)
- Chen Liang
- Corneal Refraction Department, The Second Hospital of Jilin University, Changchun, China,
| | - Yan Zhang
- Corneal Refraction Department, The Second Hospital of Jilin University, Changchun, China
| | - Yuxi He
- Corneal Refraction Department, The Second Hospital of Jilin University, Changchun, China
| | - Shurong Wang
- Corneal Refraction Department, The Second Hospital of Jilin University, Changchun, China
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Brar S, Ganesh S, Gautam M, Meher S. Feasibility, Safety, and Outcomes With Standard Versus Differential Spot Distance Protocols in Eyes Undergoing SMILE for Myopia and Myopic Astigmatism. J Refract Surg 2021; 37:294-302. [PMID: 34044689 DOI: 10.3928/1081597x-20210121-01] [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: 11/20/2022]
Abstract
PURPOSE To study the feasibility, safety, comparison of intraoperative ease of dissection, and immediate visual outcomes with standard versus differential small incision lenticule extraction (SMILE) spot settings in eyes undergoing bilateral SMILE for myopia or myopic astigmatism. METHODS One hundred eyes of 50 patients (mean age: 25.4 years) were randomized to receive standard settings (4.5-µm spot and track spacing in cap and lenticule interface) in one eye and differential settings (4.5-µm spot and track spacing in cap interface and 4.2 µm in lenticule interface) in the contralateral eye. Opaque bubble layer (OBL) was graded using a new grading system and a surgeon questionnaire was obtained to grade the ease of dissection (from 0 to 5, with 5 being the easiest) at the end of each surgery. Visual results and optical quality were analyzed at 1 day, 2 weeks, and 3 months postoperatively. RESULTS The mean OBL score was significantly lower in the differential group (26.3%) compared to the standard group (35.3%) (P < .01). Consequently, the mean dissection score was significantly higher in the differential group (4.01) compared to the standard group (3.57) (P < .01). The uncorrected distance visual acuity, Objective Scatter Index, modulation transfer function cut-off, and higher order aberrations were comparable with no statistically significant difference between both groups at 1 day, 2 weeks, and 3 months postoperatively (P > .05 for all parameters). No eye in either group had any intraoperative or postoperative complication affecting visual recovery. CONCLUSIONS Differential spot settings resulted in less intraoperative OBL and easy separability. However, the visual results and optical quality were comparable between groups. [J Refract Surg. 2021;37(5):294-302.].
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Wu D, Liu C, Li B, Wang D, Fang X. Influence of Cap Thickness on Corneal Curvature and Corneal Biomechanics After SMILE: A Prospective, Contralateral Eye Study. J Refract Surg 2020; 36:82-88. [PMID: 32032428 DOI: 10.3928/1081597x-20191216-01] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/16/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the impact of cap thickness for small incision lenticule extraction (SMILE) on changes in corneal curvature and biomechanics. METHODS One hundred eyes (50 patients) were enrolled in this prospective contralateral eye study. The difference in manifest refraction spherical equivalent (MRSE) in the same patient was less than 0.50 diopters. SMILE was performed with a randomized cap thickness of 110 µm in one eye and 140 µm in the other eye. MRSE, uncorrected distance visual acuity (UDVA), and corneal curvature and biomechanics were evaluated. The anterior and posterior surfaces of the corneal curvature (mean keratometry [Km] values 2, 4, and 6 mm from the pupil center) were measured by Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany) and changes in corneal biomechanics at 6 months postoperatively by Scheimpflug technology. RESULTS There was no significant between-group difference in UDVA or MRSE postoperatively. Postoperative changes in Km at the anterior surface (ΔKm-ant) in the 4-mm zone were significantly higher in the 110-µm group than in the 140-µm group at 1 day and 1, 3, and 6 months postoperatively (P = .043, .045, .003, and .049, respectively); at 3 months, the ΔKm-ant in the 6-mm zone was higher in the 110-µm group (P = .035). The changes in second appla-nation time, deformation amplitude, and integrated radius were significantly less in the 110-µm group (P = .031, .049, and < .001, respectively). CONCLUSIONS A thicker corneal cap caused less change in anterior surface curvature after SMILE for moderate or low myopia, with no significant difference in UDVA and MRSE. [J Refract Surg. 2020;36(2):82-88.].
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Ahmed AA, Hatch KM. Advantages of Small Incision Lenticule Extraction (SMILE) for Mass Eye and Ear Special Issue. Semin Ophthalmol 2020; 35:224-231. [PMID: 32892680 DOI: 10.1080/08820538.2020.1807028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This review summarizes the advantages of Small-incision lenticule extraction (SMILE), including improved patient intraoperative experience, improved postoperative ocular surface, low incidence of regression, low re-treatment rates, and advantageous biomechanical corneal stability. Visual and refractive outcomes are similar to those achieved with LASIK, notably in large population studies. Since the inception of SMILE almost 10 years ago, the procedure has been rapidly growing in popularity. With the implementation of the novel SMILE technology in their practice, refractive surgeons generate excitement and potential for expanding the refractive market. Other parts of the world, including Asia, Europe, and Russia, SMILE has become the most popular refractive procedure performed. It is speculated that as SMILE continues to grow in popularity in the US since FDA approval in 2016 and more refractive surgeons implement this technology into their practice, it will drive an increase in the refractive market similar to what is seen in other countries.
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Affiliation(s)
- Amani A Ahmed
- Anterior Segment - Cornea and Refractive Surgery, Mass Eye and Ear Main Campus , Boston, MA, USA.,Anterior Segment - Cornea and Refractive Surgery, Harvard University , Boston, MA, USA
| | - Kathryn M Hatch
- Anterior Segment - Cornea and Refractive Surgery, Mass Eye and Ear Main Campus , Boston, MA, USA.,Anterior Segment - Cornea and Refractive Surgery, Harvard University , Boston, MA, USA
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Wu D, Li B, Huang M, Fang X. Influence of Cap Thickness on Opaque Bubble Layer Formation in SMILE: 110 Versus 140 µm. J Refract Surg 2020; 36:592-596. [PMID: 32901826 DOI: 10.3928/1081597x-20200720-02] [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: 04/02/2020] [Accepted: 06/24/2020] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the impact of cap thickness on the formation of an opaque bubble layer (OBL) during small incision lenticule extraction procedures. METHODS In total, 100 eyes from 50 patients were prospectively examined. One of two corneal cap thicknesses was randomly assigned to each eye and differed in the contralateral eye: 110 µm in one eye and 140 µm in the other. OBL area and density were quantitatively assessed. RESULTS The proportion of OBL areas in the anterior lenticule plane was 11.70% ± 7.35% in the 110-µm group, which was significantly higher than the 140-µm group (6.64% ± 4.68%, P < .001). For OBL areas located in the posterior lenticule plane, mean areas for the 110-µm group were also higher than those for the 140-µm group (1.32% ± 1.20% and 0.94% ± 0.59%, respectively; P = .002). Mean gray values of the OBL in the posterior lenticule plane were slightly different between the two groups (P < .001), but no significant difference in OBL of the anterior lenticule plane was observed (P = .055). Eyes with a 110-µm cap thickness had more focal OBLs, revealed by cap scanning (chi-square = 10.256, P = .001). CONCLUSIONS Corneal cap thickness is predictive of opaque bubble layer during small incision lenticule extraction procedures. [J Refract Surg. 2020;36(9):592-596.].
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The best optical zone for small-incision lenticule extraction in high myopic patients. J Cataract Refract Surg 2020; 46:1302-1307. [PMID: 32569029 DOI: 10.1097/j.jcrs.0000000000000282] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Small-incision lenticule extraction (SMILE) is an effective and safe procedure for the correction of myopia due to minimally invasive and noncorneal flap surgery. However, the SMILE procedure has certain requirements for corneal cap thickness, attempted refractive correction, residual stromal bed thickness, and optical zone diameter, which sometimes make surgeons hesitant to choose SMILE or other refractive surgeries. The requirements limit its use in patients with high myopia. The purpose of this review was to find the optimal parameters of SMILE through discussing the best optical zone for high myopic patients, the visual quality of different optical zones, the choice of corneal cap thickness, and their effects on corneal biomechanical parameters, so surgeons can provide reference recommendations for patients with high myopia in choosing a reasonable and safe procedure.
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Donate D, Thaëron R. SMILE With Low Energy Levels: Assessment of Early Visual and Optical Quality Recovery. J Refract Surg 2019; 35:285-293. [DOI: 10.3928/1081597x-20190416-01] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 04/15/2019] [Indexed: 11/20/2022]
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