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Li J, Qin J, Lv X, Xu Y, Jiang D, Yuan M, Sun M, Zhang F. Study of corneal and retinal thicknesses at five years after FS-LASIK and SMILE for myopia. BMC Ophthalmol 2024; 24:396. [PMID: 39237938 PMCID: PMC11378561 DOI: 10.1186/s12886-024-03661-w] [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: 03/21/2024] [Accepted: 08/27/2024] [Indexed: 09/07/2024] Open
Abstract
BACKGROUND This study aimed to observe corneal and retinal thicknesses at 5 years after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) for myopia, investigate the effect of epithelial remodeling on refractive status and visual quality, and compare retinal thicknesses among fundus tessellation grades. METHODS Patients who received FS-LASIK or SMILE 5 years before were enrolled in this cross-sectional study. After 1:1 propensity score matching, each surgical group obtained 177 patients (177 eyes). Examinations including visual acuity, refraction, corneal and retinal thicknesses, corneal higher-order aberrations (HOAs), and fundus photography were performed in this visit at 5 years after surgery. The Quality of Vision (QoV) questionnaire was used to assess visual symptoms and overall satisfaction. Corneal and retinal thicknesses between groups were compared, contributing factors were analyzed, and correlations with postoperative refractive status, HOAs, QoV scores and overall satisfaction were evaluated. RESULTS The discrepancy of epithelial thickness between central and pericentral zones in FS-LASIK group was larger than that in SMILE group, which was negatively correlated with postoperative spherical equivalent (SE), positively correlated with spherical aberration (all P < 0.05), but not correlated with QoV scores and overall satisfaction (all P > 0.05) in both surgical groups. There was no statistical difference in stromal thickness and total corneal thickness (all P > 0.05). Most annuluses of epithelial and stromal thicknesse were linearly related to preoperative SE (all P < 0.05). The macular thickness, ganglion cell complex thickness, and retinal nerve fiber layer thickness exhibited comparable values between two surgical groups and four fundus tessellation grades, with no significant association observed with postoperative SE (all P > 0.05). CONCLUSION The tendency that epithelial thickness in central zone was thicker than peripheral zone was more obvious at 5 years after FS-LASIK compared to SMILE. This uneven distribution of epithelial thickness might play a role in myopic regression and the changes in HOAs, especially in patients with high myopia, but it had little effect on patients' subjective visual quality and satisfaction. Retinal thicknesses were not affected by these two surgical methods, and they did not appear to be the clinical indicators for myopic regression or fundus tessellation progression.
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Affiliation(s)
- Jiayu Li
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Jie Qin
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Xiaotong Lv
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Yushan Xu
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Dianjun Jiang
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Mingzhen Yuan
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Mingshen Sun
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, China
| | - Fengju Zhang
- Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Capital Medical University, Beijing, 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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Wu Y, Shen T, Tan L, He T, Zheng Q, Hong C. Corneal remodeling after SMILE for moderate and high myopia: short-term assessment of spatial changes in corneal volume and thickness. BMC Ophthalmol 2023; 23:402. [PMID: 37803347 PMCID: PMC10559442 DOI: 10.1186/s12886-023-03148-0] [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: 06/08/2023] [Accepted: 09/20/2023] [Indexed: 10/08/2023] Open
Abstract
PURPOSE To evaluate the early corneal remodeling and its influencing factors after Small incision lenticule extraction (SMILE) for moderate and high myopia. METHODS This was a retrospective study. Pre- and post-operative (1 week and 1, 3, 6 months) corneal volume (CV), mean keratometry (Km), and corneal thickness (CT) were measured by Scheimpflug tomography. CT at the central, thinnest point, and on concentric circles of 2, 4, and 6 mm diameter was recorded to assess corneal thickness spatial profile (CTSP) and percentage of thickness increase (PTI) in the moderate and high myopia groups, and to explore possible influencing factors. RESULTS After SMILE, the peripheral CT decreased in the moderate myopia group and central corneal thickness (CCT) increased in the high myopia group at 1 month compared to 1 week (all P < 0.05). The CV, Km and CT were significantly increased at 3 months compared to 1 month (all P < 0.05), but there was no significant change at 6 months compared to 3 months for both groups (all P > 0.05). Patients with high myopia showed greater corneal thickness changes (△CT) and higher PTI than moderate myopia (all P < 0.05). Regression analysis revealed that in addition to refraction, peripheral PTI was negatively correlated with CCT in the moderate myopia group (4 mm: β = -0.023, P = 0.001; 6 mm: β = -0.050, P < 0.001), as well as in the high myopia group (4 mm: β = -0.038, P < 0.001; 6 mm: β = -0.094, P < 0.001). Moreover, peripheral PTI in the moderate myopia group was negatively correlated with age (4 mm: β = -0.071, P = 0.003; 6 mm: β = -0.162, P < 0.001). CONCLUSIONS After SMILE, the CV, Km, and CTSP showed dynamic changes in the early stage, which stabilized after 3 months. Compared to the moderate myopia group, the high myopia group experienced slower corneal stabilization. The change in PTI at 6 months after SMILE may be related to higher preoperative refraction, thinner CCT and younger age.
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Affiliation(s)
- Yuanpeng Wu
- School of Public Health, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Ting Shen
- Eye Center, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
| | - Lingtong Tan
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ting He
- School of Public Health, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Qingqing Zheng
- Department of Ophthalmology, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Chaoyang Hong
- Department of Ophthalmology, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China.
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Geng Y, Hu Y, Zhang F, Tuo Y, Ge R, Bai Z. Mitochondria in hypoxic pulmonary hypertension, roles and the potential targets. Front Physiol 2023; 14:1239643. [PMID: 37645564 PMCID: PMC10461481 DOI: 10.3389/fphys.2023.1239643] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/03/2023] [Indexed: 08/31/2023] Open
Abstract
Mitochondria are the centrol hub for cellular energy metabolisms. They regulate fuel metabolism by oxygen levels, participate in physiological signaling pathways, and act as oxygen sensors. Once oxygen deprived, the fuel utilizations can be switched from mitochondrial oxidative phosphorylation to glycolysis for ATP production. Notably, mitochondria can also adapt to hypoxia by making various functional and phenotypes changes to meet the demanding of oxygen levels. Hypoxic pulmonary hypertension is a life-threatening disease, but its exact pathgenesis mechanism is still unclear and there is no effective treatment available until now. Ample of evidence indicated that mitochondria play key factor in the development of hypoxic pulmonary hypertension. By hypoxia-inducible factors, multiple cells sense and transmit hypoxia signals, which then control the expression of various metabolic genes. This activation of hypoxia-inducible factors considered associations with crosstalk between hypoxia and altered mitochondrial metabolism, which plays an important role in the development of hypoxic pulmonary hypertension. Here, we review the molecular mechanisms of how hypoxia affects mitochondrial function, including mitochondrial biosynthesis, reactive oxygen homeostasis, and mitochondrial dynamics, to explore the potential of improving mitochondrial function as a strategy for treating hypoxic pulmonary hypertension.
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Affiliation(s)
- Yumei Geng
- Key Laboratory of High Altitude Medicine (Ministry of Education), Key Laboratory of Application and Foundation for High Altitude Medicine Research in Qinghai Province (Qinghai-Utah Joint Research Key Lab for High Altitude Medicine), Research Center for High Altitude Medicine, Qinghai University, Xining, China
- Department of Respiratory and Critical Care Medicine, Qinghai Provincial People’s Hospital, Xining, China
| | - Yu Hu
- Department of Pharmacy, Qinghai Provincial Traffic Hospital, Xining, China
| | - Fang Zhang
- Department of Respiratory and Critical Care Medicine, Qinghai Provincial People’s Hospital, Xining, China
| | - Yajun Tuo
- Department of Respiratory and Critical Care Medicine, Qinghai Provincial People’s Hospital, Xining, China
| | - Rili Ge
- Key Laboratory of High Altitude Medicine (Ministry of Education), Key Laboratory of Application and Foundation for High Altitude Medicine Research in Qinghai Province (Qinghai-Utah Joint Research Key Lab for High Altitude Medicine), Research Center for High Altitude Medicine, Qinghai University, Xining, China
| | - Zhenzhong Bai
- Key Laboratory of High Altitude Medicine (Ministry of Education), Key Laboratory of Application and Foundation for High Altitude Medicine Research in Qinghai Province (Qinghai-Utah Joint Research Key Lab for High Altitude Medicine), Research Center for High Altitude Medicine, Qinghai University, Xining, China
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Hashemi H, Roberts CJ, Elsheikh A, Mehravaran S, Panahi P, Asgari S. Corneal Biomechanics After SMILE, Femtosecond-Assisted LASIK, and Photorefractive Keratectomy: A Matched Comparison Study. Transl Vis Sci Technol 2023; 12:12. [PMID: 36928130 PMCID: PMC10029763 DOI: 10.1167/tvst.12.3.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
Purpose To evaluate the change in corneal stiffness after small incision lenticule extraction (SMILE), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and photorefractive keratectomy (PRK). Methods Age, gender, spherical equivalent, and central corneal thickness (CCT)-matched cases undergoing SMILE with a 120-µ cap, FS-LASIK with a 110-µ flap, and PRK were enrolled. One-year change in the stress-strain index, stiffness parameter at first applanation, integrated inverse radius, deformation amplitude ratio at 2 mm, and deformation amplitude ratio at 1 mm were compared between the surgical groups by linear mixed-effect models. Results Within each surgical group, 120 eyes completed 1 year of follow-up. The residual stromal bed (RSB) thickness and (RSB/CCTpostop) were 348.1 ± 35.0 (0.74), 375.4 ± 31.0 (0.77) and 426.7 ± 2 µm (0.88) after SMILE, FS-LASIK, and PRK, respectively. The 1-year change in all biomechanical indices was significant, except the stress-strain index with PRK (P = 0.884). The change in all indices with SMILE were significantly greater than with FS-LASIK and with PRK (all P < 0.01), except the deformation amplitude ratio at 1 mm change between SMILE and FS-LASIK (P = 0.075). The changes in all indices with FS-LASIK were significantly greater than with PRK (all P < 0.05). Conclusions Although SMILE preserves the greatest amount of anterior cornea with a cap thickness of 120 µ, this also produces the smallest RSB and the greatest decrease in stiffness. Thus, the RSB is shown to be the predominant determinant of stiffness decreases, rather than the preserved anterior cornea. We recommend using a thinner cap to achieve a thicker RSB and a lesser decrease in the corneal stiffness in the SMILE procedure. Translational Relevance After refractive surgery, RSB is predominant determinant of stiffness decreases, rather than the preserved anterior cornea.
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Affiliation(s)
- Hassan Hashemi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Cynthia J Roberts
- Department of Ophthalmology & Visual Sciences, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK
- National Institute for Health Research (NIHR) Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China
| | - Shiva Mehravaran
- School of Computer, Mathematical, and Natural Sciences, Morgan State University, Baltimore, MD, USA
| | - Parsa Panahi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - Soheila Asgari
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
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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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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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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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Zarei-Ghanavati S, Hassanzadeh S, Ambrósio Jr R. Corneal Ectasia after Laser-Assisted Small-Incision Lenticule Extraction: The Case for an Enhanced Ectasia Risk Assessment. J Curr Ophthalmol 2022; 34:357-363. [PMID: 36644473 PMCID: PMC9832456 DOI: 10.4103/joco.joco_79_22] [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: 03/01/2022] [Revised: 03/26/2022] [Accepted: 04/05/2022] [Indexed: 12/12/2022] Open
Abstract
Purpose To present a case of asymmetric progressive corneal ectasia following femtosecond laser-assisted small-incision lenticule extraction. Methods After obtaining a patient's consent, preoperative and postoperative findings were represented in this case report. Results A 29-year-old woman presented with normal preoperative Placido disk-based corneal topography and tomographic findings. The corrected refractive error was -4.00 and -4.50 -1.00 × 177 in the right and left eye, respectively, with a maximal lenticule thickness of 87 and 115 μm OD/OS. Twenty months postoperatively, the patient presented with decreased vision in the left eye and mild ectatic changes in corneal shape in both eyes. The retrospective evaluation of the integrated rotating Scheimpflug tomography (Pentacam; Oculus, Wetzlar, Germany) and corneal biomechanical (Corvis ST) assessment revealed moderate susceptibility for corneal ectasia in the right eye and a significant corneal ectasia in the left eye. Conclusion This case corroborates the need for an enhanced multimodal approach to characterize the risk for postoperative corneal ectasia after laser vision correction.
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Affiliation(s)
- Siamak Zarei-Ghanavati
- Eye Research Center, Department of Ophthalmology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Samira Hassanzadeh
- Refractive Error Research Center, Department of Optometry, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Renato Ambrósio Jr
- Instituto de Olhos Renato Ambrósio/Visare Personal Laser, and Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
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Zhang D, Tian L, Zhang H, Zheng Y, Fu C, Zhai C, Jie Y, Li L. Differences of Corneal Biomechanics Among Thin Normal Cornea, Forme-Fruste Keratoconus, and Cornea After SMILE. Front Bioeng Biotechnol 2022; 10:861924. [PMID: 35646859 PMCID: PMC9136087 DOI: 10.3389/fbioe.2022.861924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
Background: To compare the corneal biomechanics of thin normal cornea (TNC) with thinnest corneal thickness (TCT) (≤500 µm), forme-fruste keratoconus (FFKC) and cornea after small incision lenticule extraction (Post-SMILE) had their central corneal thickness (CCT) matched by Corneal Visualization Scheimpflug Technology (Corvis ST).Methods: CCT were matched in 23 eyes with FFKC, 23 eyes by SMILE in 3 months post-operatively, and 23 TNC eyes. The differences in corneal biomechanics by Corvis ST among the three groups were compared.Results: There was no significant difference in CCT among the three groups, and the biomechanically corrected intraocular pressure (bIOP) did not differ significantly among the three groups (all p > 0.05). There were significant differences in most DCR parameters between pre- and post-operatively (all p < 0.05). Compared with TNC, the values of corneal deflection amplitude during the first applanation (A1DA), length at the first applanation (A1L), corneal deflection amplitude during the second applanation (A2DA), and maximum deformation amplitude (DA) decreased in 3 months after SMILE (all p < 0.05), these values increased in the FFKC (all p < 0.05).Conclusion: The majority of the DCR parameters were different among the three groups. The parameters A1DA, A1L, A2DA, and DA may be different between TNC and Post-SMILE, TNC and FFKC, and Post-SMILE and FFKC.
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Affiliation(s)
- Di Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-based Precision Medicine, Capital Medical University, Beijing, China
| | - Lei Tian
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beijing Tongren Hospital, Beihang University and Capital Medical University, Beijing, China
| | - Haixia Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-based Precision Medicine, Capital Medical University, Beijing, China
| | - Yan Zheng
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Caiyun Fu
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Changbin Zhai
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- *Correspondence: Lin Li, ; Changbin Zhai, ; Ying Jie,
| | - Ying Jie
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- *Correspondence: Lin Li, ; Changbin Zhai, ; Ying Jie,
| | - Lin Li
- School of Biomedical Engineering, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-based Precision Medicine, Capital Medical University, Beijing, China
- *Correspondence: Lin Li, ; Changbin Zhai, ; Ying Jie,
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12
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Zhang D, Qin X, Zhang H, Li L. Time-varying regularity of changes in biomechanical properties of the corneas after removal of anterior corneal tissue. Biomed Eng Online 2021; 20:113. [PMID: 34801040 PMCID: PMC8606087 DOI: 10.1186/s12938-021-00948-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 11/03/2021] [Indexed: 11/13/2022] Open
Abstract
Background The corneal biomechanical properties with the prolongation of time after corneal refractive surgery are important for providing a mechanical basis for the occurrence of clinical phenomena such as iatrogenic keratectasia and refractive regression. The aim of this study was to explore the changes of corneal elastic modulus, and stress relaxation properties from the 6-month follow-up observations of rabbits after a removal of anterior corneal tissue in simulation to corneal refractive surgery. Methods The anterior corneal tissue, 6 mm in diameter and 30–50% of the original corneal thickness, the left eye of the rabbit was removed, and the right eye was kept as the control. The rabbits were normally raised and nursed for 6 months, during which corneal morphology data, and both of corneal hysteresis (CH) and corneal resistance factor (CRF) were gathered. Uniaxial tensile tests of corneal strips were performed at months 1, 3, and 6 from 7 animals, and corneal collagen fibrils were observed at months 1, 3, and 6 from 1 rabbit, respectively. Results Compared with the control group, there were statistical differences in the curvature radius at week 2 and month 3, and both CH and CRF at months 1, 2, and 6 in experiment group; there were statistical differences in elastic modulus at 1, 3, and month 6, and stress relaxation degree at month 3 in experiment group. The differences in corneal elastic modulus, stress relaxation degree and the total number of collagen fibrils between experiment and control groups varied gradually with time, and showed significant changes at the 3rd month after the treatment. Conclusions Corneas after a removal of anterior corneal tissue undergo dynamic changes in corneal morphology and biomechanical properties. The first 3 months after treatment could be a critical period. The variation of corneal biomechanical properties is worth considering in predicting corneal deformation after a removal of anterior corneal tissue.
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Affiliation(s)
- Di Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Xiao Qin
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Haixia Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
| | - Lin Li
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
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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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Jun I, Kang DSY, Roberts CJ, Lee H, Jean SK, Kim EK, Seo KY, Kim TI. Comparison of Clinical and Biomechanical Outcomes of Small Incision Lenticule Extraction With 120- and 140-µm Cap Thickness. Transl Vis Sci Technol 2021; 10:15. [PMID: 34259803 PMCID: PMC8288062 DOI: 10.1167/tvst.10.8.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to compare the clinical outcomes and corneal biomechanical changes between 120-µm and 140-µm cap thickness after small incision lenticule extraction (SMILE). Methods This prospective study included 150 eyes (150 patients: 91 eyes in the 120-µm group, and 59 eyes in the 140-µm group) who underwent SMILE. Enhanced correction nomograms were applied for patients according to cap thickness. Clinical outcomes, including visual acuity, refraction, and corneal wavefront aberrations, were compared between the two groups. Corneal biomechanics were evaluated using the Corvis ST (Oculus, Wetzlar, Germany). Results The mean uncorrected-distance visual acuity, safety and efficacy indices, and refractive predictability were comparable in the 120-µm and 140-µm groups after SMILE. The postoperative total corneal root mean square higher-order aberrations (HOAs) and spherical aberrations was 0.48 ± 0.31 and 0.26 ± 0.10 in the 120-µm group, and 0.53 ± 0.16 and 0.34 ± 0.13 in the 140-µm group, which showed significant differences between the two groups (P = 0.027, and <0.001, respectively). Although corneal stiffness decreased after SMILE in both groups, the changes in the deformation amplitude ratio were significantly higher in the 140-µm group than in the 120-µm group (P = 0.022). Conclusions SMILE with 120-µm and 140-µm cap thickness provided excellent predictable outcomes according to our enhanced correction nomogram. The amount of tissue removal required to achieve the same amount of refractive correction was greater in the thicker cap group. The induction of corneal HOAs and weakening of corneal biomechanics were less pronounced in the thin-cap group, which may be associated with the thinner cap, lesser lenticule thickness, or thicker residual stromal bed. Translational Relevance Although SMILE with different cap thickness was effective, thicker lenticule thickness in the thick-cap group may be associated with induction of HOAs, and corneal stiffness changes.
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Affiliation(s)
- Ikhyun Jun
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea.,Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | | | - Cynthia J Roberts
- Department of Ophthalmology & Visual Sciences and Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Hun Lee
- Department of Ophthalmology, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | | | - Eung Kweon Kim
- Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea.,Saevit Eye Hospital, Goyang-Si, Gyeonggi-Do, Republic of Korea
| | - Kyoung Yul Seo
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Tae-Im Kim
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea.,Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea
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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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Chong JK, Hamilton DR. SMILE for Myopic Astigmatism: Early Experience in the USA and International Advances. CURRENT OPHTHALMOLOGY REPORTS 2020. [DOI: 10.1007/s40135-020-00250-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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