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Bohač M, Gabrić I, Gabrić K, Jagić M, Arba Mosquera S. Predictability of the Achieved Lenticule Thickness in Keratorefractive Lenticule Extraction for Myopia Correction. J Refract Surg 2023; 39:728-735. [PMID: 37937760 DOI: 10.3928/1081597x-20230925-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
PURPOSE To assess the predictability between the SCHWIND ATOS femtosecond laser (SCHWIND eye-tech-solutions) read-out and achieved lenticule thickness measured using MS-39 anterior segment optical coherence tomography (ASOCT; CSO) at the corneal vertex at postoperative 1 day and 1 and 3 months of follow-up. METHODS This retrospective case series included 130 eyes of 65 consecutive patients who were treated with SmartSight (SCHWIND eye-tech-solutions) lenticule extraction. Sixty-four percent of patients were women with a mean spherical refraction of -4.98 ± 1.19 diopters (D) and mean astigmatism of 0.53 ± 0.64 D. The measurements were performed using AS-OCT with the Phoenix Software v 4.1.1.5. Lenticule thickness was obtained by the subtraction method between preoperative and postoperative total corneal thickness. RESULTS A lower reduction in central corneal thickness (CCT) compared to the laser read-out for all three follow-up visits can be observed. Essentially, the reduction in CCT was identical at 3 months versus 1 month. The reduction in CCT was lowest at postoperative 1 day. Examining the 1- and 3-month data (essentially equivalent), one can see a best fit of y = 0.94 x -7 µm. CONCLUSIONS The reduction in CCT was stable from 1 month of follow-up. The stable reduction in CCT was -6% (-1.5% after accounting for design decisions) and -7 µm lower than the respective laser read-out. The findings are predictable, showing a certain level of the lenticules becoming slightly thinner than their respective laser read-outs. [J Refract Surg. 2023;39(11):728-735.].
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Lu X, Fan Y, Liu Z, Qiu X, Shi Q, Gao N, Mi S, Pei C. Comparison of planned versus achieved central corneal stromal thickness reduction in SMILE versus FS-LASIK: a retrospective study. Sci Rep 2023; 13:9956. [PMID: 37340090 DOI: 10.1038/s41598-023-37143-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/16/2023] [Indexed: 06/22/2023] Open
Abstract
Accuracy of planned corneal stromal thickness (CST) reduction is essential to the safety of laser vision correction. This study was to compare the accuracy of the planned central CST reduction in small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). A total of 77 patients (43 for SMILE, 34 for FS-LASIK using Custom-Q algorithm) were included in this retrospective study. At postoperative 6-18 months, the central CST reduction was overestimated by 18.49 ± 6.42 μm in the SMILE group (P < 0.001) and underestimated by 2.56 ± 7.79 μm in the FS-LASIK group (P = 0.064). The planned-achieved difference (PAD) of central CST reduction was positively correlated with preoperative manifest refraction spherical equivalent (MRSE) and with planned central CST reduction in both groups. When calculated by manifest refraction (MR) without nomogram adjustment, the central CST reduction was overestimated by 11.14 ± 6.53 μm in the SMILE group and underestimated by 2.83 ± 7.39 μm in the FS-LASIK group. The PAD of central CST reduction without nomogram was significantly narrowed in SMILE and maintained in FS-LASIK, suggesting estimation using MR without nomogram adjustment may be feasible for SMILE and FS-LASIK in clinical practice.
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Affiliation(s)
- Xueqing Lu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Yimeng Fan
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Zhao Liu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China.
| | - Xuanyu Qiu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Qiang Shi
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Ning Gao
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Shengjian Mi
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Cheng Pei
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Road, Xi'an, 710061, Shaanxi, China
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Liu S, Zhou X, Zhao Y. Comparison of Predictability in Central Corneal Thickness Reduction After SMILE and FS-LASIK for High Myopia Correction. Ophthalmol Ther 2023; 12:549-559. [PMID: 36517698 PMCID: PMC9834448 DOI: 10.1007/s40123-022-00629-1] [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: 10/13/2022] [Accepted: 11/30/2022] [Indexed: 01/12/2023] Open
Abstract
INTRODUCTION To compare central corneal thickness (CCT) reduction after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) in eyes with high myopia. METHODS In this prospective, consecutive study, 70 eyes with high myopia undergoing SMILE (n = 35) or FS-LASIK (n = 35) were recruited. Corneal topography images were acquired using the Pentacam HR imaging system preoperatively and at 1 day, 1 month, and 6 months postoperatively. Predicted CCT reduction was extracted directly from the VisuMax femtosecond laser system or MEL 80 excimer laser platform. The achieved CCT reduction was determined using corneal thickness difference maps from the Pentacam. Comparative statistics and linear regression analyses were performed to evaluate the predictability in stromal thickness reduction. RESULTS The mean predicted CCT reductions were 152.9 ± 6.7 μm and 150.9 ± 7.3 μm in the FS-LASIK and SMILE groups, respectively, with no statistical difference. For each follow-up time, no significant difference was noted in the two groups in the achieved CCT reduction. At 6-month follow-up, the CCT reductions were overestimated to be 23.06 ± 6.97 µm and 28.29 ± 13.92 µm in the SMILE and FS-LASIK groups, respectively (P = 0.003), showing statistical difference. Regression analysis revealed that the positive correlation between achieved and predicted CCT reductions was stronger in SMILE (R2 = 0.5065, P < 0.001) than in FS-LASIK (R2 = 0.2237, P = 0.004). Overestimated CCT reduction was not correlated with predicted CCT reduction in either group. CONCLUSIONS Systematically overestimated CCT reduction is found after SMILE and FS-LASIK in high myopia correction. Deviations between planned and achieved CCT reductions are more pronounced in FS-LASIK than in SMILE.
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Affiliation(s)
- Shengtao Liu
- Department of Ophthalmology and Optometry, Eye and ENT Hospital of Fudan University, 83 Fenyang Road, Shanghai, 200031 People’s Republic of China ,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China ,Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China ,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China ,Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Xingtao Zhou
- Department of Ophthalmology and Optometry, Eye and ENT Hospital of Fudan University, 83 Fenyang Road, Shanghai, 200031 People’s Republic of China ,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China ,Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China ,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China ,Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Yu Zhao
- Department of Ophthalmology and Optometry, Eye and ENT Hospital of Fudan University, 83 Fenyang Road, Shanghai, 200031 People’s Republic of China ,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China ,Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China ,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China ,Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
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Investigation of Accuracy and Influence Factors of Predicting Lenticule Thickness in Small Incision Lenticule Extraction by Machine Learning Models. J Pers Med 2023; 13:jpm13020256. [PMID: 36836490 PMCID: PMC9959370 DOI: 10.3390/jpm13020256] [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: 01/03/2023] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/03/2023] Open
Abstract
Small-incision lenticule extraction (SMILE) is a safe and effective surgical procedure for refractive correction. However, the nomogram from the VisuMax femtosecond laser system often overestimates the achieved lenticule thickness (LT), leading to inaccurate estimation of residual central corneal thickness in some patients. In order to improve the accuracy of predicting achieved LT, we used machine learning models to make predictions of LT and analyze the influencing factors of LT estimation in this study. We collected nine variables of 302 eyes and their LT results as input variables. The input variables included age, sex, mean K reading of anterior corneal surface, lenticule diameter, preoperative CCT, axial length, the eccentricity of the anterior corneal surface (E), diopter of spherical, and diopter of the cylinder. Multiple linear regression and several machine learning algorithms were employed in developing the models for predicting LT. According to the evaluation results, the Random Forest (RF) model achieved the highest performance in predicting the LT with an R2 of 0.95 and found the importance of CCT and E in predicting LT. To validate the effectiveness of the RF model, we selected additional 50 eyes for testing. Results showed that the nomogram overestimated LT by 19.59% on average, while the RF model underestimated LT by -0.15%. In conclusion, this study can provide efficient technical support for the accurate estimation of LT in SMILE.
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Luo Y, He S, Chen P, Yao H, He A, Li Y, Qiu J, Lan M, Zhuang J, Yu K. Predictability of Central Corneal Stromal Reduction After SMILE and FS-LASIK for High Myopia Correction: A Prospective Randomized Contralateral Eye Study. J Refract Surg 2022; 38:90-97. [DOI: 10.3928/1081597x-20211112-01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wu F, Yin H, Chen X, Yang Y. Investigation of predictability and influence factors of the achieved lenticule thickness in small incision lenticule extraction. BMC Ophthalmol 2020; 20:110. [PMID: 32183750 PMCID: PMC7079481 DOI: 10.1186/s12886-020-01374-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/06/2020] [Indexed: 11/11/2022] Open
Abstract
Background To evaluate the differences between the predicted and achieved lenticule thickness (ΔLT) after small incision lenticule extraction (SMILE) surgery and investigate relationships between ΔLT and predicted lenticule thickness in SMILE. Methods A total of 184 eyes from 184 consecutive patients who underwent SMILE were included in this prospective study. One eye for each patient was randomly selected and included for statistical analysis. To achieve emmetropia, nomogram adds 10% correction of spherical refractive. An ultrasound pachymetry measurement and Scheimpflug camera corneal topography were obtained before and at 3 months after SMILE. The achieved lenticule thickness was calculated by comparing the preoperative examinations with postoperative examinations using ultrasound pachymetry and Pentacam software measurements. The pupil center and corneal vertex were selected as the 2 locations for measurement calculation on Pentacam. Analysis of variance (ANOVA) was performed to compare mean pachymetry values using different instruments. Linear regression analyses were performed between the VisuMax readout lenticule thicknesses and the measured maximum corneal change, between ΔLT and predicted lenticule thickness. Results On average, the achieved lenticule thickness measured with ultrasound pachymetry was 13.02 ± 8.87 μm thinner than the predicted lenticule thickness. The proportion of ΔLT in predicted values is 11.9% (ultrasound) and about 15% (Pentacam). Linear regression analysis showed significant relationships between the predicted and each achieved lenticule thickness. Each ΔLT was significantly related to predicted lenticule thickness (ultrasound: R2 = 0.242; pupil center from Pentacam: R2 = 0.230). Conclusions An overestimation of achieved lenticule thickness was evident in this study which may exclude eligible SMILE patient. Also, our results showed that 10% increase of spherical refractive correction in the nomogram is appropriate. Furthermore, clinicians should subtract 10% of the predicted lenticule thickness to calculate the residual corneal stroma bed thickness.
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Affiliation(s)
- Fang Wu
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Jie Fang Road 88#, Hangzhou, 310009, People's Republic of China
| | - Houfa Yin
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Jie Fang Road 88#, Hangzhou, 310009, People's Republic of China
| | - Xinyi Chen
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Jie Fang Road 88#, Hangzhou, 310009, People's Republic of China
| | - Yabo Yang
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Jie Fang Road 88#, Hangzhou, 310009, People's Republic of China.
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Tay E, Bajpai R. Small incision lenticule extraction (SMILE) lenticule thickness readout compared to change in axial length measurements with the IOLMaster. Graefes Arch Clin Exp Ophthalmol 2019; 258:917-924. [PMID: 31773250 DOI: 10.1007/s00417-019-04529-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 09/12/2019] [Accepted: 10/28/2019] [Indexed: 11/28/2022] Open
Abstract
PURPOSE To compare theoretical values from the small incision lenticule extraction (SMILE) lenticule thickness readout with change in axial length measurements taken with the IOLMaster. METHODS We prospectively studied 214 eyes from 107 patients undergoing bilateral SMILE surgery for myopia or myopic astigmatism between December 2014 and May 2017 at an ophthalmological practice in Singapore. All eyes were examined pre-operatively and 1 and 3 months post-operatively with the IOLMaster following SMILE surgery. Achieved lenticule thickness was taken as the change in axial length after surgery. A linear mixed-effects model was used to examine changes in axial length, spherical equivalent and acuity over time. The relationships between change in axial length and theoretical lenticule thickness and spherical equivalent were examined with multiple linear regression analyses, and model prediction was assessed with adjusted R2 statistics. RESULTS Mean (95% confidence interval [CI]) spherical equivalent pre-operatively was - 5.25 (95% CI - 5.38 to - 5.12) diopters (D), at 1 month was 0.04 (95% CI - 0.09 to 0.17) D (p < 0.001), and at 3 months was - 0.02 (95% CI - 0.15 to 0.11) D (p < 0.001). Mean (95% CI) pre-operative axial length was 27,726 (95% CI 25,595 to 25,857) μm. Post-operative axial length at 1 month was significantly shorter at 25,595 (95% CI 25,464 to 25,726) μm (p < 0.001) with no change thereafter (p = 0.647). Pre-operative mean ± standard deviation (SD) refractive target was 0.24 (± 0.3) D, and mean difference between target and post-operative spherical equivalent at 1 month was 0.20 D (95% CI 0.16 to 0.25 D, p < 0.001). Multiple regression analysis showed that change in axial length at 1 month was, on average, 5% lower than theoretical lenticule thickness, indicating an average difference of 5.4 μm (95% CI 5.2 to 5.6 μm). Preoperative spherical equivalent predicted negative association with change in axial length at 1 month (β = - 14.8, 95% CI - 18.2 to - 11.3, adjusted R2 = 0.457, p < 0.001). CONCLUSIONS Calculated lenticule thickness values were less than expected, and post-operative refractive outcomes at 1 month showed a slight under-correction. Further research in this area is needed to validate these findings.
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Affiliation(s)
- Eugene Tay
- Singapore Eye Research Institute, The Academia, 20 College Road, Singapore, 169856, Singapore.
| | - Ram Bajpai
- Centre for Population Health Sciences, Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore, 308232, Singapore.,School of Primary, Community and Social Care, Keele University, Staffordshire, ST5 5BG, United Kingdom
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