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Sedaghat MR, Momeni-Moghaddam H, Yekta AA, Maddah N, Roberts CJ, Savardashtaki M. Early elastic and viscoelastic corneal biomechanical changes after photorefractive keratectomy and small incision lenticule extraction. Int Ophthalmol 2024; 44:302. [PMID: 38954134 DOI: 10.1007/s10792-024-03169-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 06/15/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE To compare early changes in the corneal biomechanical parameters after photorefractive keratectomy (PRK) and small incision lenticule extraction (SMILE) and their correlations with corneal shape parameters. METHODS One hundred twenty four eyes received myopic PRK and SMILE for similar amounts of myopia. Corneal tomography with Pentacam HR, biomechanical parameters using Corvis ST, and Ocular Response Analyzer (ORA) were evaluated before and 2 weeks after surgery. The change in each parameter was compared between groups, while the difference in central corneal thickness and cornea-compensated intraocular pressure measured before and after surgery were considered as covariates. RESULTS A significant reduction was seen in the corneal stiffness parameter at first applanation, and an increase in deformation amplitude ratio (DAR), and integrated inverse radius (IIR) in both groups after surgery (p < 0.001) Changes in DAR, and IIR were significantly greater in the SMILE than in the PRK group (p < 0.001) Corneal hysteresis (CH) and corneal resistance factor (CRF) decreased in both SMILE and PRK groups after surgery, (p < 0.001) with no statistically significant difference between groups (p > 0.05) Among new Corvis ST parameters, DAR showed a significant correlation with changes in Ambrosio relational thickness in both groups (p < 0.05). CONCLUSIONS Both techniques caused significant changes in corneal biomechanics in the early postoperative period, with greater elastic changes in the SMILE group compared to the PRK group, likely due to lower tension in the SMILE cap and thinner residual stromal bed in SMILE. There were no differences in viscoelastic changes between them, so the lower CH may reflect the volume of tissue removed.
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Affiliation(s)
| | - Hamed Momeni-Moghaddam
- Rehabilitation Sciences Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
| | - Abbas-Ali Yekta
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Nasim Maddah
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Sciences; and Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Maryam Savardashtaki
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
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Chen S, Ma H, Zhao C. Corneal biomechanics after small incision lenticule extraction and femtosecond laser in situ keratomileusis: A systematic review and meta-analysis. Medicine (Baltimore) 2023; 102:e34580. [PMID: 37565903 PMCID: PMC10419641 DOI: 10.1097/md.0000000000034580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 07/13/2023] [Indexed: 08/12/2023] Open
Abstract
BACKGROUND Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) have been extensively studied as the main surgical methods for corneal refractive surgery. However, there is no consensus on whether SMILE is superior to FS-LASIK in corneal biomechanics. Therefore, this systematic review and meta-analysis used the results of ocular response analyzer and corvis ST to explore whether SMILE is superior to FS-LASIK in corneal biomechanics. METHODS The literature was searched in PubMed, EMBASE, and Controlled Trials Register databases. The Cochrane Collaboration's "risk of bias" tool was used to evaluate the quality of the included randomized clinical trials, and the Newcastle-Ottawa Scale was used to evaluate the included non-randomized controlled trials. The results were analyzed using Revman 5.3. RESULTS Sixteen studies (3 randomized clinical trials and 13 non-randomized controlled trials) were included in this meta-analysis. There was no statistical difference in corneal biomechanics between SMILE and FS-LASIK in corneal hysteresis [mean difference (MD), 0.20; 95% confidence interval (CI): -0.09, 0.49; P = .18] and corneal resistant factor (MD, 0.31; 95% CI: -0.09, 0.71; P = .13), A1 time (MD, -0.02; 95% CI: -0.11, 0.07; P = .66), A1 length (MD, 0.01; 95% CI: -0.01, 0.03; P = .42), A1 velocity (MD, 0.00; 95% CI: -0.01, 0.01; P = .85), A2 velocity (MD, -0.01; 95% CI: -0.11, 0.09; P = .86), HC time (MD, 0.12; 95% CI: -0.13, 0.38; P = .35), The stiffness parameter at first applanation (MD, -7.91; 95% CI: -17.96, 2.14; P = .12), The ratio between the deformation amplitude 2 mm away from apex and the apical deformation (MD, 0.01; 95% CI: -0.26, 0.27; P = .96). CONCLUSION A comprehensive assessment of the parameters of ocular response analyzer and corvis ST showed that SMILE is not superior to LASIK in corneal biomechanics 3 months post-surgery.
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Affiliation(s)
- Songbai Chen
- Aier Huangpi Eye Hospital, Wuhan, Hubei Province, China
| | - Hongjie Ma
- Zhengzhou Aier Eye Hospital, Zhengzhou, Henan Province, China
| | - Congling Zhao
- Aier Huangpi Eye Hospital, Wuhan, Hubei Province, China
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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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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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Clinical Outcomes Comparison of Combined Small Incision Lenticule Extraction with Collagen Cross-Linking Versus Small Incision Lenticule Extraction Only. J Ophthalmol 2022; 2022:2625517. [PMID: 36267955 PMCID: PMC9578865 DOI: 10.1155/2022/2625517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 06/28/2022] [Accepted: 08/25/2022] [Indexed: 12/04/2022] Open
Abstract
Purpose To evaluate clinical outcome during 24 months follow-up between small incision lenticule extraction combined with cross-linking (SMILE Xtra) and small incision lenticule extraction (SMILE) only. Setting. Ophthalmology Division of San Rossore Medical Center, Pisa, Italy. Design Retrospective comparative case series. Methods The study comprised 70 eyes (35 patients); 40 eyes were corrected using SMILE and 30 eyes were corrected using SMILE Xtra using a low energy protocol. The outcomes were compared at 1, 6, 12, and 24 months postoperatively. Results The mean spherical equivalent (SEQ) reduced from −7.18 ± 1.21 D to −0.01 ± 0.09 D in the SMILE group and from −6.20 ± 2.99 D to −0.04 ± 0.1 D postoperatively in SMILE Xtra (p < 0.05). At 24 months the mean SEQs were −0.01 ± 0.24 D for SMILE and −0.15 ± 0.33 D for SMILE Xtra (p > 0.05). At 1, 6, 12, and 24 months, there were no statistically significant differences between the SMILE and SMILE Xtra groups in logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA), safety, and efficacy index (p > 0.05). The mean average keratometry (K-avg) at 1, 6, 12, and 24 months after surgery did not shown any statistically significant difference between SMILE and SMILE Xtra group (p > 0.05). The mean maximum keratometry (K-max) readings at 1, 6, 12, and 24 months were not statistically significant between SMILE and SMILE Xtra group (p > 0.05). The preoperative mean thinnest point pachymetry (TTP) was 543.90 ± 22.85 μm in the SMILE group and 523.40 ± 37.01 μm in the SMILE Xtra group (p < 0.05). At 1, 6, 12, and 24 months the mean TTP was not statistically significant between the SMILE and SMILE Xtra groups (p > 0.05). At 24 months, the TTP was 408.29 ± 38.75 μm for the SMILE group and 402.22 ± 37 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the mean maximum posterior elevation (MPE) was 8.63 ± 4.35 μm for SMILE and 8.13 ± 2.54 μm for SMILE Xtra (p > 0.05). After the surgical procedure, both groups showed a statistically significant increase of the MPE (p < 0.05). At 24 months, the MPE was 11.00 ± 4.72 μm for SMILE Xtra and 10.14 ± 3.85 μm for the SMILE group (p > 0.05). In the preoperative period, the means of the root mean square (RMS) of high-order aberration (HOA) were 0.08 ± 0.03 μm for the SMILE group and 0.08 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the RMS of HOA was 0.13 ± 0.07 μm for the SMILE group and 0.14 ± 0.07 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the root mean square of coma aberration (RMS-Coma) aberration was 0.06 ± 0.09 μm for the SMILE group and 0.04 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the coma aberration of SMILE group was 0.12 ± 0.21 μm and 0.16 ± 0.25 μm for SMILE Xtra group (p > 0.05). Conclusions SMILE Xtra procedure is a safe and simple procedure that can be offered to patients with high corneal ectasia risk because there were no differences in the indices of ectasia compared to the group treated only with SMILE which has a low corneal ectatic risk.
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Han T, Zhao L, Shen Y, Chen Z, Yang D, Zhang J, Sekundo W, Shah R, Tian J, Zhou X. Twelve-year global publications on small incision lenticule extraction: A bibliometric analysis. Front Med (Lausanne) 2022; 9:990657. [PMID: 36160168 PMCID: PMC9493269 DOI: 10.3389/fmed.2022.990657] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose To analyze the development process of small incision lenticule extraction (SMILE) surgery in a 12-year period. Methods We conducted a literature search for SMILE research from 2011 to 2022 using the Science Citation Index Expanded (SCIE) of the Web of Science Core Collection (WoSCC). The VOS viewer, and CiteSpace software were used to perform the bibliometric analysis. Publication language, annual growth trend, countries/regions and institutions, journals, keywords, references, and citation bursts were analyzed. Results A total of 731 publications from 2011 to 2022 were retrieved. Annual publication records grew from two to more than 100 during this period. China had the highest number of publications (n = 326). Sixty-five keywords that appeared more than four times were classified into six clusters: femtosecond laser technology, dry eye, biomechanics, visual quality, complications, and hyperopia. Conclusion The number of literatures has been growing rapidly in the past 12 years. Our study provides a deep insight into publications on SMILE for researchers and clinicians with bibliometric analysis for the first time.
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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
| | - Liang Zhao
- Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou, China
- The School of Nursing, Lanzhou University, Lanzhou, Gansu, 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
| | - Zhi 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
| | - Dong Yang
- 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
| | - Jiaoyan Zhang
- Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou, China
- The School of Nursing, Lanzhou University, Lanzhou, Gansu, China
| | - Walter Sekundo
- The Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany
| | - Rupal Shah
- New Vision Laser Centers, Vadodara, Gujarat, India
| | - Jinhui Tian
- Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou, China
- *Correspondence: Jinhui Tian,
| | - 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
- Xingtao Zhou,
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Hou J, Wang Y, Zhang J, Lei Y, Ma Z, Zhang Y, Zheng X. Corneal densitometry after allogeneic small-incision intrastromal lenticule implantation for hyperopia correction. BMC Ophthalmol 2022; 22:286. [PMID: 35764952 PMCID: PMC9241174 DOI: 10.1186/s12886-022-02454-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/11/2022] [Indexed: 11/12/2022] Open
Abstract
Purpose To evaluate corneal densitometry after allogeneic corneal small-incision intrastromal lenticule implantation (SILI) for hyperopia. Methods A retrospective study. Thirty-one hyperopic eyes of 24 patients who underwent SILI were enrolled in this study. Examinations took place preoperatively and 1 week, 1 month, 3 months, and 6 months postoperatively. Corneal densitometry (CD) from different concentric radial zones (0–2, 2–6, and 6–10 mm annulus) and layers (anterior, central, and posterior) were obtained using Scheimpflug imaging. The association between CD changes and the uncorrected distance visual acuity (UDVA), spherical equivalent (SE), central corneal thickness (CCT) and K value were examined. Results No serious intraoperative complications occurred during SILI. The mean total CD increased postoperatively compared to preoperatively (P < 0.01). However, no significant differences were found among the four subsequent follow-up time points (P > 0.05). At 6 months postoperatively, the CD values showed an increase of 2.71 ± 2.52, 2.23 ± 2.25, and 1.87 ± 2.46 at the 0–2, 2–6, and 6–10 mm annuli, respectively (all at P < 0.01). The anterior 120 μm displayed the highest densitometry before and after surgery (all at P < 0.01). No significant increase was found within the posterior 60 μm of the cornea (P > 0.05). No correlation was found between the CD and relevant parameters(all at P > 0.05). Conclusions SILI resulted in an increase in CD within the surgically altered area, however such change has no significant correlation with visual outcomes.
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Affiliation(s)
- Jie Hou
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, China
| | - Yan Wang
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Jing Zhang
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, China
| | - Yulin Lei
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, China.
| | - Zhixing Ma
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, China
| | - Ying Zhang
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, China
| | - Xiuyun Zheng
- Jinan Mingshui Eye Hospital, Number 5601, Longquan Road, Zhangqiu District, 250200, Jinan, 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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Min JS, Min BM. Clinical Outcomes of Laser Asymmetric Keratectomy to Manage Postoperative Adverse Effects–A Retrospective Clinical Trial. Open Ophthalmol J 2021. [DOI: 10.2174/1874364102115010171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background:
Laser asymmetric keratectomy reduces the regional asymmetry of corneal thickness.
Objective:
We aimed to describe the clinical outcomes of laser asymmetric keratectomy keratectomy with laser refractive surgery performed to resolve the adverse effects following ophthalmic surgeries.
Methods:
We compared the preoperative and postoperative outcomes and complaints of blurring after performing laser asymmetric keratectomy with laser refractive surgery in 24 eyes of 16 patients with a deviation sum in corneal thickness in four directions >80 µm. Laser asymmetric keratectomy with laser refractive surgery, with full integration of the Vision Up software, was used to analyze the corneal thickness deviation, employed selective laser ablation to create central symmetry on the thicker cornea to reduce regional asymmetry of corneal thickness, simultaneously correcting the refractive power and myopic shift. The pre-and postoperative clinical and topographic findings were analyzed.
Results:
The patients’ age was 37.57±22.30 (range, 23–65) years. The follow-up period was 16.56±3.23 months. The spherical equivalent (p=0.026), sphere (p=0.022), uncorrected distance visual acuity (LogMAR, p=0.045), blurring score (p=0.000), central corneal thickness (p=0.024), sum of deviations in corneal thickness in four directions (p=0.02), distance between the maximum posterior elevation and visual axis (p=0.04), and kappa angle (p=0.031), significantly decreased postoperatively. The efficiency and safety indices were 0.96±0.11 and 1.00, respectively. There was no myopic regression or blurred vision postoperatively.
Conclusion:
Performing laser asymmetric keratectomy with laser refractive surgery improved corneal symmetry and visual acuity and reduced blurring.
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Kenia VP, Kenia RV, Pirdankar OH. Short term changes in corneal stress-strain index and other corneal biomechanical parameters post-laser in situ keratomileusis. Indian J Ophthalmol 2021; 69:2650-2656. [PMID: 34571607 PMCID: PMC8597531 DOI: 10.4103/ijo.ijo_3365_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Purpose: To report the short-term changes in a corneal stress-strain index (SSI) and other corneal biomechanical parameters post-laser in situ keratomileusis (LASIK) surgery. Methods: A retrospective study was conducted at a tertiary eye care center wherein patients who had undergone LASIK (microkeratome blade and femtosecond bladeless LASIK) between July and December 2019 were enrolled. Patients of age group 20–40 years, best-corrected visual acuity of 20/20, intraocular pressure (IOP) <22 mmHg, pre-LASIK pachymetry >500 microns, and corneal astigmatism ≤3.00 D were included. Subjects with a prior history of refractive surgery, any other ocular or systemic disease, poor-quality scans, intraoperative complications, and missing data were excluded. Corneal biomechanical properties including SSI were analyzed using Corvis ST and compared using the Paired T-test for each group separately at pre-LASIK, and 1-month post-operatively. Results: Overall, 202 eyes were reviewed, and 79 eyes fulfilled the inclusion criteria. Forty-three and 36 eyes had undergone Microkeratome Blade LASIK (Group I) and Femto LASIK (Group II), respectively. Overall, 29 and 26 corneal biomechanical parameters out of 33 changed significantly post-Microkeratome Blade LASIK and Femto LASIK, respectively. Statistically significant changes were noted in all the parameters at A1, maximum and Vinciguerra screening parameters (P < 0.001), however, no changes were noted in SSI in both the groups when compared with the pre-surgery data. Conclusion: Though the reduction in SSI was not statistically significant, other biomechanical parameters showed significant biomechanical changes pre- and post-LASIK surgeries in both the groups. However, a long-term study with a larger sample size would be required to understand the changes and stability in SSI post-refractive surgery.
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Comparison of 1-Year Outcomes Between Small Incision Lenticule Extraction With Prophylactic Cross-Linking and Femtosecond Laser-Assisted In Situ Keratomileusis With Prophylactic Cross-Linking. Cornea 2021; 40:12-18. [PMID: 33214416 DOI: 10.1097/ico.0000000000002547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare small incision lenticule extraction with prophylactic cross-linking (SMILE Xtra) and femtosecond laser-assisted in situ keratomileusis with prophylactic cross-linking (FS-LASIK Xtra) in their safety, efficacy, predictability, and stability. METHODS This is a prospective cohort study. Forty-eight eyes subjected to SMILE Xtra and 90 eyes subjected to FS-LASIK Xtra were enrolled. The enrolled eyes exhibited either borderline corneal topography or high myopia with thin cornea. The following parameters were evaluated before surgery and at 1 day; 1 week; and 1, 3, 6, and 12 months after surgery: corrected distance visual acuity, uncorrected distance visual acuity, manifest refractive spherical equivalent (MRSE), keratometry values, and thinnest corneal thickness. RESULTS After 1 month, no eye showed loss of 1 or more lines of corrected distance visual acuity. At 12 months, uncorrected distance visual acuity was 20/20 or better for 98% and 99% eyes in the SMILE Xtra and FS-LASIK Xtra groups, respectively (P = 0.657). For 93.8% eyes in the SMILE Xtra group and 90% eyes in the FS-LASIK Xtra group, the achieved MRSE was within ±0.50 diopter of the intended MRSE (P = 0.669). The correlation coefficients for predictability of MRSE correction by SMILE Xtra and FS-LASIK Xtra were 0.987 and 0.983, respectively. The mean MRSE values, keratometry values, and thinnest corneal thickness measured at the different time points showed no significant intra- or intergroup differences. CONCLUSIONS Our evaluations of 1-year outcomes suggest that the safety, efficacy, predictability, and stability of SMILE Xtra are comparable with those of FS-LASIK Xtra.
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Song Y, Fang L, Zhu Q, Du R, Guo B, Gong J, Huang J. Biomechanical responses of the cornea after small incision lenticule extraction (SMILE) refractive surgery based on a finite element model of the human eye. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:4212-4225. [PMID: 34198433 DOI: 10.3934/mbe.2021211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
PURPOSE To investigate the biomechanical responses of the human cornea after small incision lenticule extraction (SMILE) procedures, especially their effects of SMILE surgery on stress and strain. METHODS Based on finite element analysis, a three-dimensional (3D) model of the human eye was established to simulate SMILE refractive surgery procedures. Stress and strain values were calculated by inputting the intraocular pressure (IOP). RESULTS After SMILE refractive surgery procedures, the stress and strain of the anterior and posterior corneal surfaces were significantly increased. The equivalent stress and strain on the anterior and posterior corneal surfaces increased with increasing diopter and were concentrated in the central area, whereas the values of stress and strain at the incision site on the anterior surface of the cornea were approximately 0. Compared with the anterior corneal surface, the stress and strain of the posterior surface were larger. Increasing IOP caused an approximately linear change in stress and a nonlinear increase in corneal strain. In addition, we found that the incision sizes and direction had less of an influence on stress and strain. In summary, SMILE surgery increased the equivalent stress and strain on the human cornea. CONCLUSIONS The equivalent stress and strain of the anterior and posterior human corneal surfaces increased after SMILE refractive surgery; these increases were particularly noticeable on the posterior surface of the cornea.
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Affiliation(s)
- Yinyu Song
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Lihua Fang
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Qinyue Zhu
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Ruirui Du
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Binhui Guo
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Jiahui Gong
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
| | - Jixia Huang
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
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Min JS, Min BM. A Novel Approach to Enhancement Linked Laser Asymmetric Keratectomy Using Semi-Cylindrical Ablation Pattern in Patients with Myopic Regression After Laser Refractive Surgery. Clin Ophthalmol 2021; 15:1751-1758. [PMID: 33935491 PMCID: PMC8080158 DOI: 10.2147/opth.s306636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 04/09/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose We aimed to introduce a new technique to reduce regional asymmetry of corneal thickness by assessing its effectiveness in four patients with myopic regression after laser refractive surgery (LRS). Patients and Methods Four patients (four eyes) with myopic regression after LRS were included in this study. A new technique of enhancement with laser epithelial keratomileusis-linked laser asymmetric keratectomy using semi-cylindrical ablation pattern (E-LAK-SCAP) with full integration of the Vision-Up software for analyzing the corneal thickness deviation can be used to create central symmetry by blocking laser ablation on the thin cornea. It reduces the regional asymmetry of the corneal thickness, thus improving corneal symmetry and correcting the refractive power and myopic shift due to E-LAK-SCAP. We measured refraction, visual acuity, intraocular pressure (IOP), central corneal thickness (CCT), corneal irregularities in the 3.0mm, and 5.0 zones on Orbscan maps, the sum of corneal thickness deviations in four directions (SUM), distance between the maximum posterior elevation (best-fit-sphere [BFS]) and the visual axis (DISTANCE), and angle kappa before and after LRS and E-LAK-SCAP. Blurring scores were measured before and after E-LAK-SCAP. Results The uncorrected far visual acuity (LogMAR) increased after LRS and E-LAK-SCAP. SUM (µm) increased after LRS in three cases, but decreased in all four cases after E-LAK-SCAP. DISTANCE increased after LRS, but decreased after E-LAK-SCAP. The spherical equivalent, CCT, decreased after LRS and E-LAK-SCAP. Blurring scores decreased after E-LAK-SCAP, and angle kappa was similar before and after LRS, but decreased after E-LAK-SCAP. IOP was similar before and after both LRS and E-LAK-SCAP. Conclusion E-LAK-SCAP improved corneal symmetry by reducing the SUM and DISTANCE, showing good postoperative visual acuity, and blurring was reduced postoperatively. There was no myopic regression in the one-year postoperative period.
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Affiliation(s)
- Ji Sang Min
- Kim's Eye Hospital, Division of Cornea, Cataract, and Refractive Surgery, Konyang University School of Medicine, Seoul, South Korea
| | - Byung Moo Min
- Woori Eye Clinic, Department of Ophthalmology, Yonsei University School of Medicine, Daejon, South Korea
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14
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Min JS, Min BM. Comparison of outcomes of laser refractive surgery (LRS) alone and LRS with laser asymmetric keratectomy in patients with myopia: A retrospective study. Medicine (Baltimore) 2021; 100:e25366. [PMID: 33832118 PMCID: PMC8036046 DOI: 10.1097/md.0000000000025366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 03/11/2021] [Indexed: 01/05/2023] Open
Abstract
To compare and analyze the postoperative 1-year outcomes of laser refractive surgery (LRS) alone vs LRS with laser asymmetric keratectomy (LAK), in patients with myopia, for preventing and resolving LRS complications.This retrospective study compared the preoperative and 1-year postoperative outcomes between the control and comparison groups using a sum of deviations in corneal thickness in 4 directions >80 μm. The control group included 41 patients with myopia (41 eyes) who underwent LRS. The comparison group included 33 patients (33 eyes) who received LAK-linked LRS. Age, spherical equivalent (SE), sphere, cylinder, uncorrected distance visual acuity (UDVA), pupil size, kappa angle, central corneal thickness, corneal irregularity in the 3.0 mm zone on Orbscan maps (SUM), distance between the maximum posterior elevation (best-fit-sphere) and the visual axis (DISTANCE), postoperative blurring scores, frequency of postoperative myopic regression, and efficiency index were compared.Preoperative age (P = .198), SE (P = .686), sphere (P = .562), cylinder (P = .883), UDVA (P = .139), pupil size (P = .162), kappa angle (P = .807), central corneal thickness (P = .738), corneal irregularity (P = .826), SUM (P = .774), and DISTANCE (P = .716) were similar between the 2 groups. The 1-year postoperative SE (P = .024), sphere (P = .022), corneal irregularity (P = .033), SUM (P = .000), DISTANCE (P = .04), blurring scores (P = .000), and frequency of postoperative myopic regression (P = .004) were significantly decreased in the comparison group compared to the control group. UDVA (P = .014) and the efficiency index (P = .035) were higher in the comparison group.LAK with LRS improved corneal symmetry by reducing the SUM and DISTANCE. UDVA and efficiency index were also improved and blurring and myopic regression were reduced postoperatively.
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Affiliation(s)
- Ji Sang Min
- Kim's Eye Hospital, Division of Cornea,Cataract, and Refractive Surgery. Konyang University School of Medicine. Youngdeungpo-gu, Seoul
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15
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Abstract
The emergence of SMILE in the last decade has provided an alternative to LASIK for patients considering cornea laser refractive surgery. SMILE offers a novel approach using the femtosecond laser to create an intrastromal lenticule that can be removed through a small three to four millimeter incision.The purpose of this study is to review the recent literature on popular SMILE claims - reduced iatrogenic dry eye, better recovery of corneal sensation, and a biomechanically stronger cornea - summarize the published outcomes, and determine which claims are myths versus realities.SMILE is still in its infancy as a refractive technique in the US after recent USFDA approval for its treatment of myopia astigmatism in October 2018. Future randomized controlled studies are needed to compare its outcomes to LASIK, which has well-documented good visual outcomes, rapid postoperative recovery, and good safety profile.
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Affiliation(s)
- Grace Huang
- Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.,Boston Eye Group, Brookline, MA, USA
| | - Samir Melki
- Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.,Boston Eye Group, Brookline, MA, USA
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16
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Advances in Imaging Technology of Anterior Segment of the Eye. J Ophthalmol 2021; 2021:9539765. [PMID: 33688432 PMCID: PMC7925029 DOI: 10.1155/2021/9539765] [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] [Received: 06/22/2020] [Revised: 02/05/2021] [Accepted: 02/16/2021] [Indexed: 12/27/2022] Open
Abstract
Advances in imaging technology and computer science have allowed the development of newer assessment of the anterior segment, including Corvis ST, Brillouin microscopy, ultrahigh-resolution optical coherence tomography, and artificial intelligence. They enable accurate and precise assessment of structural and biomechanical alterations associated with anterior segment disorders. This review will focus on these 4 new techniques, and a brief overview of these modalities will be introduced. The authors will also discuss the recent advances in research regarding these techniques and potential application of these techniques in clinical practice. Many studies on these modalities have reported promising results, indicating the potential for more detailed comprehensive understanding of the anterior segment tissues.
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Abstract
Myopia, also known as short-sightedness or near-sightedness, is a very common condition that typically starts in childhood. Severe forms of myopia (pathologic myopia) are associated with a risk of other associated ophthalmic problems. This disorder affects all populations and is reaching epidemic proportions in East Asia, although there are differences in prevalence between countries. Myopia is caused by both environmental and genetic risk factors. A range of myopia management and control strategies are available that can treat this condition, but it is clear that understanding the factors involved in delaying myopia onset and slowing its progression will be key to reducing the rapid rise in its global prevalence. To achieve this goal, improved data collection using wearable technology, in combination with collection and assessment of data on demographic, genetic and environmental risk factors and with artificial intelligence are needed. Improved public health strategies focusing on early detection or prevention combined with additional effective therapeutic interventions to limit myopia progression are also needed.
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18
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Vanathi M, Azimeera S, Gupta N, Tandon R. Study on change in corneal biomechanics and effect of percent tissue altered in myopic laser-assisted in situ keratomileusis. Indian J Ophthalmol 2020; 68:2964-2974. [PMID: 33229679 PMCID: PMC7856945 DOI: 10.4103/ijo.ijo_1453_20] [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] [Indexed: 11/04/2022] Open
Abstract
Purpose To evaluate corneal biomechanical changes and their correlation with the percentage of tissue altered (PTA) in myopic femtosecond (FS)-flap LASIK. Methods Prospective longitudinal observational study of 80 eyes of FS LASIK. Demographic details, LASIK parameters, preoperative and postoperative (day 1, month 1, 3, and 6), UCVA, BCVA, refraction, corneal topography, corneal hysteresis (CH), and a corneal resistance factor (CRF) were noted. Change in CH and CRF and its correlation with PTA were analyzed. Data were analyzed in three subgroups [subgroup 1: PTA 23 to <27%; subgroup 2: 27 to <33%; subgroup 3: 33 to <40%]. Results FS LASIK for MRSE -3.5D ± 1.6D with mean PTA of 31.6 ± 4.4% (range 23.8-39.8%), showed statistically significant decrease in CH and CRF. Mean CH decreased from a preoperative value of 10.4 ± 1.9 to 8.1 ± 1.1; mean CRF from 10.5 ± 1.6 to 7.5 ± 1.3 at 6-months postoperative period, respectively. Mean preoperative CH decreased by 25%, 24%, 23%, and 21% and mean preoperative CRF decreased by 34%, 28%, 28%, and 28% at postoperative day 1, month 1, 3, and 6 follow-ups. Mean CH and CRF showed a significant negative correlation with PTA (CH: r = - 0.33 [P = <0.0001], CRF: r = -0.34 [P = <0.001]. Subgroup analysis noted greater decrease in CRF and CH in eyes with higher PTA (subgroup 3). Conclusion Myopic FS LASIK causes a decrease in corneal biomechanics with a significant negative correlation with PTA indicating a greater decrease in corneal biomechanics with higher PTA.
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Affiliation(s)
- Murugesan Vanathi
- Cornea, Cataract and Refractive Services, Dr Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Suresh Azimeera
- Cornea, Cataract and Refractive Services, Dr Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Noopur Gupta
- Cornea, Cataract and Refractive Services, Dr Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Radhika Tandon
- Cornea, Cataract and Refractive Services, Dr Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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Asif MI, Bafna RK, Mehta JS, Reddy J, Titiyal JS, Maharana PK, Sharma N. Complications of small incision lenticule extraction. Indian J Ophthalmol 2020; 68:2711-2722. [PMID: 33229647 PMCID: PMC7856979 DOI: 10.4103/ijo.ijo_3258_20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The procedure of small incision lenticule extraction (SMILE) was introduced in 2011, and since then there has been an increase in the number of cases undergoing this procedure worldwide. The surgery has a learning curve and may be associated with problems in the intraoperative and postoperative periods. The intraoperative problems during SMILE surgery include the loss of suction, the occurrence of altered or irregular opaque bubble layer and black spots, difficulty in lenticular dissection and extraction, cap perforation, incision-related problems, and decentered ablation. Most of the postoperative problems are similar as in other laser refractive procedures, but with decreased incidence. The identification of risk factors, clinical features, and management of complications of SMILE help to obtain optimum refractive outcomes.
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Affiliation(s)
- Mohamed Ibrahime Asif
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Rahul Kumar Bafna
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Jodhbir Singh Mehta
- Singapore Eye Research Institute; Singapore National Eye Centre, 168751; Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Medical School, Singapore
| | - Jagadesh Reddy
- Cataract and Refractive Services, Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Jeewan Singh Titiyal
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Prafulla K Maharana
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Namrata Sharma
- Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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20
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Abd El-Fattah EA, El Dorghamy AA, Ghoneim AM, Saad HA. Comparison of corneal biomechanical changes after LASIK and F-SMILE with CorVis ST. Eur J Ophthalmol 2020; 31:1762-1770. [PMID: 32698618 DOI: 10.1177/1120672120945664] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate changes in corneal biomechanics after LASIK and F-SMILE. SETTING Elite Eye Center, Tanta, Egypt. DESIGN Prospective, randomized, unmasked, interventional comparative case series. PATIENTS AND METHODS A total of 60 eyes were equally divided into two groups; group A: received LASIK and group B: received F-SMILE. Pentacam and CorVis ST parameters were compared before and 6 months after procedures. P ⩽ 0.05 was used for significance of results. RESULTS bIOP decreased by 0.762 ± 1.211 mmHg in group A (p = 0.092), and by 2.52 ± 1.389 mmHg in group B (p < 0.001) and the difference between groups became significant (p = 0.001). A1 increased significantly in group A only (p = 0.036); while A2 decreased insignificantly in both groups. DAR increased significantly in both groups (p < 0.001, p = 0.022), but the difference between groups remained insignificant (p = 0.461). IR increased significantly in group A only (p < 0.001) and the difference between groups became significant (p = 0.026). ARTH decreased in both groups (p = 0.245, p = 0.695) and the difference remained insignificant (p = 0.928). SP-A1 decreased in group A by 8.89 ± 1.38 mmHg/mm (p = 0.637), and by 32.6 ± 4.39 mmHg/mm in group B (p < 0.001) and the postoperative difference between groups was significant (p = 0.013). CBI increased significantly in group A (p < 0.001), but insignificantly in group B (p = 0.098) and postoperative difference between groups was highly significant (p < 0.001). A significant correlation was found between change in CCT and corresponding changes in DAR, IR, and ARTH after surgery in both groups. CONCLUSION The significant differences between groups postoperatively as regards bIOP (p = 0.001), IR (p = 0.026), SP-A1 (p = 0.013), and CBI (p < 0.001) indicate stiffer corneas after F-SMILE and suggest less influence on corneal biomechanics than LASIK.
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Affiliation(s)
- Eman A Abd El-Fattah
- Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
| | - Alaa A El Dorghamy
- Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
| | - Ahmed M Ghoneim
- Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
| | - Hisham A Saad
- Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
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21
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Min JS, Min BM. Comparison between Surgical Outcomes of LASIK with and without Laser Asymmetric Keratectomy to Avoid Conventional Laser Refractive Surgery Adverse Effects. Sci Rep 2020; 10:10446. [PMID: 32591559 PMCID: PMC7319985 DOI: 10.1038/s41598-020-67269-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/17/2020] [Indexed: 11/19/2022] Open
Abstract
This study compared one-year postoperative outcomes of laser refractive surgery combined with laser asymmetric keratectomy (LAK) and laser in situ keratomileusis (LASIK)for myopia correction in middle-aged patients (aged 40–49 years) with a total corneal thickness deviation (summed across four directions) ≥ 80 microns. The control group (n = 26; 52 eyes) underwent LASIK; the comparison group (n = 26; 52 eyes) underwent combined laser refractive surgery and LAK. Age, spherical equivalence, uncorrected visual acuity (near and far), corneal irregularity on the Orbscan map, sum of corneal thickness deviations in four directions, corneal thickness distribution, distance between the maximum posterior elevation (best-fit sphere; BFS) and visual axis, and postoperative blurring scores were analysed retrospectively between the groups. Both groups had similar preoperative findings. Postoperatively, the sum of corneal thickness deviations in four directions (p = 0.000), distance between maximum posterior elevation (BFS) and visual axis (p = 0.003),blurring score (p = 0.001), and corneal irregularity in the 3.0 and 5.0 mm zones on the Orbscan map (p = 0.033 and p < 0.0001, respectively) were significantly lower in the comparison group (p = 0.000). LAK reduced total corneal thickness deviation, improved corneal symmetry, and reduced blurring scores significantly, one-year postoperatively. LAK could resolve shortcomings of LASIK, producing better surgical outcomes.
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Affiliation(s)
- Ji Sang Min
- Department of Ophthalmology, Yonsei University School of Medicine, Seoul, South Korea
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22
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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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Khamar P, Shetty R, Vaishnav R, Francis M, Nuijts RMMA, Sinha Roy A. Biomechanics of LASIK Flap and SMILE Cap: A Prospective, Clinical Study. J Refract Surg 2019; 35:324-332. [PMID: 31059582 DOI: 10.3928/1081597x-20190319-01] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 03/19/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To analyze the acute effect of flap cut in laser in situ keratomileusis (LASIK) eyes and cap cut in small incision lenticule extraction (SMILE) eyes on corneal biomechanical properties of patients undergoing surgery. METHODS This was a prospective, interventional, longitudinal case series. Forty-eight eyes of 24 patients underwent contralateral LASIK and SMILE. Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) measurements were performed preoperatively, intraoperatively, and 1 week and 1 month after surgery. In LASIK eyes, the flap was cut but not lifted before intraoperative measurements. In SMILE eyes, the cap and side cut incision were made before intraoperative measurement. Thirty biomechanical variables were analyzed, assuming multiple comparisons. RESULTS In LASIK and SMILE eyes, 36.7% and 13.3% of the total number of variables detected biomechanical weakening after flap and cap cuts (P = .02), respectively. Further, 13.3% and 40% of the total variables detected no biomechanical changes after flap and cap cut, respectively (P = .03). These acute biomechanical effects of flap and cap cuts did not influence 1-week and 1-month measurements (P > .05) because both LASIK and SMILE eyes showed similar biomechanical weakening. CONCLUSIONS Flap and cap cuts induced biomechanical weakening in patient corneas. The flap caused more weakening than the cap intraoperatively. However, biomechanical differences between LASIK and SMILE eyes were similar after removal of tissue and ongoing wound healing. [J Refract Surg. 2019;35(5):324-332.].
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24
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Ong HS, Farook M, Tan BBC, Williams GP, Santhiago MR, Mehta JS. Corneal Ectasia Risk And Percentage Tissue Altered In Myopic Patients Presenting For Refractive Surgery. Clin Ophthalmol 2019; 13:2003-2015. [PMID: 31686775 PMCID: PMC6798818 DOI: 10.2147/opth.s215144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/13/2019] [Indexed: 01/01/2023] Open
Abstract
Purpose A percentage tissue altered (PTA) score of ≥40% has been advocated as an independent indicator of post-operative ectasia risk following laser in-situ keratomileusis (LASIK). This study was performed to test the hypothesis that refractive procedures, such as laser-assisted sub-epithelial keratectomy (LASEK) or small incision lenticule extraction (SMILE), may alter the range of PTA, within which refractive corneal surgery can be safely performed. Setting Refractive department, tertiary ophthalmic hospital. Design Retrospective observational study. Methods Review of case notes was performed for patients who presented for refractive surgeries, other than LASIK. To determine the risk of corneal ectasia for each patient prior to refractive surgery, we estimated what each patient’s PTA would have been if they had undergone LASIK. The Randleman Ectasia Risk Score System (ERSS) was also calculated. Results 114 eyes (66 patients) were included. 94 eyes underwent SMILE. 20 eyes underwent LASEK. A significant proportion of eyes had PTA ≥40% – SMILE eyes: up to 31.9%, LASEK eyes: up to 60.0% (at presumed LASIK flap of 120 μm). The maximum calculated PTA was up to 47.9% in the SMILE group and up to 51.5% in the LASEK group. Using ERSS, 12.8–16% of SMILE eyes and 15.0–80.0% of LASEK eyes would have been considered to have moderate-to-high ectasia risk. No post-surgical ectasia was observed at 3 years. Conclusion SMILE and LASEK alter the range of PTA, within which corneal refractive surgery may be performed with a lower risk of developing post-operative corneal ectasia; a safe PTA threshold needs to be determined for these procedures before recommendations for clinical practice can be made.
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Affiliation(s)
- Hon Shing Ong
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore.,SingHealth Duke-NUS Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Mohamed Farook
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore
| | - Benjamin Boon Chuan Tan
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore
| | - Geraint P Williams
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | - Marcony R Santhiago
- Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil
| | - Jodhbir S Mehta
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore.,SingHealth Duke-NUS Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Graduate Medical School, Singapore, Singapore.,School of Material Science and Engineering, Nanyang Technological University, Singapore, Singapore
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Changes in corneal biomechanics during small-incision lenticule extraction (SMILE) and femtosecond-assisted laser in situ keratomileusis (FS-LASIK). Lasers Med Sci 2019; 35:599-609. [DOI: 10.1007/s10103-019-02854-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
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Guo H, Hosseini-Moghaddam SM, Hodge W. Corneal biomechanical properties after SMILE versus FLEX, LASIK, LASEK, or PRK: a systematic review and meta-analysis. BMC Ophthalmol 2019; 19:167. [PMID: 31370817 PMCID: PMC6676534 DOI: 10.1186/s12886-019-1165-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 07/12/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The aim of this study was to compare the postoperative corneal biomechanical properties between small incision lenticule extraction (SMILE) and other corneal refractive surgeries. METHODS A systematic review and meta-analysis were conducted. Articles from January 2005, to April 2019, were identified searching PubMed, EMBASE, Web of Science, and International Clinical Trials Registry Platform. Studies that compared SMILE with other corneal refractive surgeries on adult myopia patients and evaluated corneal biomechanics were included. Multiple effect sizes in each study were combined. Random-effects model was conducted in the meta-analysis. RESULTS Twenty-two studies were included: 5 randomized controlled trials (RCTs), 9 prospective and 6 retrospective cohort studies, and 2 cross-sectional studies. Using the combined effect of corneal hysteresis (CH) and corneal resistance factor (CRF), which were obtained from ocular response analyzer (ORA), the pooled Hedges' g of SMILE versus femtosecond laser-assisted in situ keratomileusis (FS-LASIK) was 0.41 (95% CI, 0.00 to 0.81; p = 0.049; I2 = 78%), versus LASIK was 1.31 (95% CI, 0.54 to 2.08; p < 0.001; I2 = 77%), versus femtosecond lenticule extraction (FLEX) was - 0.01 (95% CI, - 0.31 to 0.30; p = 0.972; I2 = 20%), and versus the group of photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (LASEK) was - 0.26 (95% CI, - 0.67 to 0.16; p = 0.230; I2 = 54%). The summary score of Corvis ST (CST) after SMILE was comparable to FS-LASIK/LASIK with the pooled Hedges' g = - 0.05 (95% CI, - 0.24 to 0.14; p = 0.612, I2 = 55%). CONCLUSIONS In terms of preserving corneal biomechanical strength after surgeries, SMILE was superior to either FS-LASIK or LASIK, while comparable to FLEX or PRK/LASEK group based on the results from ORA. More studies are needed to apply CST on evaluating corneal biomechanics after refractive surgeries.
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Affiliation(s)
- Hui Guo
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | | | - William Hodge
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada. .,Department of Ophthalmology, Ivey Eye Institute, St. Joseph's Health Care London, 268 Grosvenor St., London, ON, Canada.
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Konstantopoulos A, Liu YC, Teo EP, Nyein CL, Yam GH, Mehta JS. Corneal Stability of LASIK and SMILE When Combined With Collagen Cross-Linking. Transl Vis Sci Technol 2019; 8:21. [PMID: 31143527 PMCID: PMC6526961 DOI: 10.1167/tvst.8.3.21] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 04/03/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose We investigate whether small incision lenticule extraction (SMILE) is associated with less ectasia than laser-assisted in-situ keratomileusis (LASIK) and whether concomitant collagen cross-linking (CXL) is protective in SMILE Xtra and LASIK Xtra. Methods Using an established LASIK rabbit ectasia model, we performed −5 diopter (D) LASIK on six eyes and −5 D SMILE on six eyes; five eyes had −5 D LASIK Xtra, five eyes −5 D SMILE Xtra. Anterior segment optical coherence tomography and corneal topography were performed preoperatively and 2, 4, and 6 weeks postoperatively. Mean (standard deviation [SD]) values of postoperative keratometry (K), maximum posterior elevation (MPE) and minimum corneal thickness (CT) were compared to preoperatively and among the surgical groups (paired t-test, analysis of variance). Results Mean (SD) K values decreased significantly following SMILE, SMILE Xtra, LASIK, and LASIK Xtra. The MPE increased significantly (P < 0.05) following LASIK, SMILE, and SMILE Xtra, but not following LASIK Xtra (P = 0.12). The MPE was less following SMILE than LASIK, but not statistically significant (week 2, 17.73 [5.77] vs. 22.75 [5.05] μm; P = 0.13); post-LASIK Xtra MPE was less than that following LASIK (week 2. 13.39 [3.05] vs. 22.75 [5.05] μm; P < 0.001). CT decreased significantly in all surgical groups; no differences were detected among the groups. Conclusions SMILE may have less potential than LASIK to induce ectasia. LASIK Xtra and SMILE Xtra showed the smallest increase in MPE. Translational Relevance Concomitant CXL may be protective following keratorefractive surgery and may reduce further the risk of ectasia.
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Affiliation(s)
- Aris Konstantopoulos
- Singapore Eye Research Institute, Singapore.,University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Yu-Chi Liu
- Singapore Eye Research Institute, Singapore.,Singapore National Eye Centre, Singapore.,Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore
| | | | | | - Gary H Yam
- Singapore Eye Research Institute, Singapore
| | - Jodhbir S Mehta
- Singapore Eye Research Institute, Singapore.,Singapore National Eye Centre, Singapore.,Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.,Nanyang Technological University, Singapore
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Corneal Safety and Stability in Cases of Small Incision Lenticule Extraction with Collagen Cross-Linking (SMILE Xtra). J Ophthalmol 2019; 2019:6808062. [PMID: 31098325 PMCID: PMC6487093 DOI: 10.1155/2019/6808062] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/14/2019] [Indexed: 01/01/2023] Open
Abstract
Purpose To assess the safety and stability in cases of small incision lenticule extraction with collagen cross-linking (SMILE Xtra). Methods This study was a retrospective interventional comparative study that included 60 eyes of 30 patients divided equally into two groups: SMILE Xtra and SMILE alone. The inclusion criteria were patients >18 years of age, myopic error >6 D, thinner cornea <520 microns, and abnormal corneal topography. Outcome data were recorded including uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA), manifest refraction spherical equivalent (MRSE), central corneal thickness, average keratometry, endothelial cell density, corneal resistance factor (CRF), and corneal densitometry. The follow-up period was 24 months. Results There was a significant difference between the 2 groups regarding UDVA, CDVA, and MRSE at 1 month. In the SMILE Xtra group, 90% of eyes had postoperative UDVA of 20/20 and 97% had UDVA of 20/30 at 24 months. At 24 months, 26 eyes (87%) vs. 25 eyes (84%) were within ±0.50 D of attempted correction in SMILE Xtra and SMILE groups, respectively. Regarding stability, both groups showed improvement of MRSE at 1st month postoperatively and remained stable along the 24 months of follow-up. CRF and corneal densitometry were higher in the SMILE Xtra group along the whole follow-up period (p=0.001). Conclusion Combining corneal cross-linking with SMILE procedure (SMILE Xtra) is a promising tool to prevent ectasia in high-risk patients. It is a safe and simple procedure that can be offered to patients undergoing SMILE with risk for ectasia. Trial registration no: PACTR201810577524718.
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Pniakowska Z, Jurowski P. Influence of preoperative astigmatism on corneal biomechanics and accurate intraocular pressure measurement after micro-incision phacoemulsification. Int J Ophthalmol 2019; 12:587-591. [PMID: 31024811 DOI: 10.18240/ijo.2019.04.10] [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: 01/18/2018] [Accepted: 01/08/2019] [Indexed: 11/23/2022] Open
Abstract
AIM To define the corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) prior to and following coaxial micro-incision phacoemulsification in patients with corneal astigmatism. METHODS Of 97 patients with cataracts were enrolled in the study. Group 1 included patients with corneal astigmatism (K1-K2) values of K1-K2<+1.0 D, and group 2 with values of K1-K2 ≥+1.0 D and ≤+2.25 D. Coaxial micro-incision phacoemulsification of a corneal incision of 2.0 mm with intraocular lens (IOL) implantation was performed. CH, CRF, IOPg, IOPcc, waveform score (WS) were measured preoperatively and one week, one month postoperatively using an Ocular Response Analyzer. Axial length (AXL) was calculated by Tomey Optical Biometer OA 2000. RESULTS Group 1 consisted of 51 patients with mean corneal astigmatism value of +0.49±0.25 D. Group 2 included 46 patients with astigmatism of +1.43±0.43 D. In group 1, CRF (t=2.68, P<0.05), CH (t=2.64, P<0.05) and WS (t=3.51, P<0.05) were significantly lower one week postoperatively, when compared to the preoperative values. CRF significantly decreased (t=3.61, P<0.05) when measured one month following the surgery. In group 2 CH (t=5.92, P<0.05), and WS (t=3.96, P<0.05) were significantly lowered one week after cataract surgery. Moreover, we observed a significant decrease in IOPg (t=2.24, P<0.05), CRF (t=5.05, P<0.05) and CH (t=2.31, P<0.05) one month after phacoemulsification. There was no statistically significant (t=-0.83, P=0.41) difference in AXL between study groups. CONCLUSION CRF, CH and IOPg are reduced in patients with preoperative corneal astigmatism equal or higher than +1.0 D and lower than +2.25 D. Hence, bias of IOPg measurement in these patients may cause underestimation of the real IOP both before and after cataract surgery. The measurement of IOPcc allows the precise assessment of IOP pre- and postoperatively, independently on corneal astigmatism, CH and CRF values.
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Affiliation(s)
- Zofia Pniakowska
- Department of Ophthalmology and Visual Rehabilitation, the Veterans Central Hospital, Lodz 90-549, Poland
| | - Piotr Jurowski
- Department of Ophthalmology and Visual Rehabilitation, the Veterans Central Hospital, Lodz 90-549, Poland
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Wallace HB, Misra SL, Li SS, McKelvie J. Biomechanical changes in the cornea following cataract surgery: A prospective assessment with the Corneal Visualisation Scheimpflug Technology. Clin Exp Ophthalmol 2019; 47:461-468. [PMID: 30474314 DOI: 10.1111/ceo.13451] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/02/2018] [Accepted: 11/09/2018] [Indexed: 01/26/2023]
Abstract
IMPORTANCE Intraocular pressure (IOP) is often reduced following cataract surgery. Postoperative changes in corneal stiffness are likely to be at least partly responsible for any reduction in IOP measured with applanation tonometry. BACKGROUND To determine the effect of cataract surgery and corneal incision size on corneal biomechanics. DESIGN Prospective randomized trial. PARTICIPANTS One hundred prospectively enrolled patients qualifying for cataract surgery. METHODS Participants were randomized to clear corneal incisions with a 2.20 or 2.85 mm keratome. Corneal Visualisation Scheimpflug Technology (Corvis-ST) tonometry and dynamic corneal response measurements were obtained preoperatively, and 3 mo postoperatively. Multiple regression analysis was completed using R software. MAIN OUTCOME MEASURES Corvis-ST biomechanical parameters. RESULTS Ninety-three eyes of 93 patients were included in the final analysis. Mean Corvis-ST biomechanically corrected IOP decreased by 3.63 mmHg postoperatively (95% confidence interval = 2.97-4.35, P ≤ 0.01), and central pachymetry increased by 6.96 μm (4.33-9.59, P ≤ 0.01). Independent of IOP and pachymetry changes, mean (±SE) corneal first applanation stiffness parameter reduced by 9.761 ± 3.729 (P = 0.01) postoperatively. First applanation velocity increased by 0.007 ± 0.002 ms, second applanation velocity increased by 0.012 ± 0.004 ms (P ≤ 0.01), the first applanation deformation amplitude increased by 0.008 ± 0.002 mm (P ≤ 0.01) and the deflection amplitude at highest concavity increased by 0.030 ± 0.069 (P ≤ 0.01). There were no significant differences between different incision size groups. CONCLUSIONS AND RELEVANCE Corneal stiffness is reduced 3 mo following cataract surgery and is associated with falsely low IOP measurements. This finding may be important for glaucoma patients and in particular when assessing the effectivity of minimally invasive glaucoma surgery devices.
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Affiliation(s)
- Henry B Wallace
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Stuti L Misra
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Sunny S Li
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - James McKelvie
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
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El-Barbry H, Ahmed K, El-Gohary S. Comparing the corneal biomechanical stability after small incision lenticule extraction and laser-assisted in situ keratomileusis for myopic correction using an ultra-high-speed camera (Corvis ST). ACTA ACUST UNITED AC 2019. [DOI: 10.4103/mmj.mmj_761_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Contralateral Eye Comparison Between 2 Cap Thicknesses in Small Incision Lenticule Extraction: 110 Versus 130 μm. Cornea 2018; 38:617-623. [DOI: 10.1097/ico.0000000000001835] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Wang KJ, Wang WW, Tsai CL, Wang IJ. Intraocular pressure changes in eyes with small incision lenticules and laser in situ keratomileusis. Clin Exp Optom 2018; 102:399-405. [PMID: 30556213 DOI: 10.1111/cxo.12861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 10/11/2018] [Accepted: 10/29/2018] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Measuring intraocular pressure after refractive surgery is a challenge in the diagnosis, evaluation, and treatment of glaucoma. Intraocular pressure characteristics after laser in situ keratomileusis (LASIK) are well known. However, intraocular pressure measurement and characteristics after small incision lenticule extraction (SMILE) are still unknown, providing an interesting point of comparison in terms of biomechanical differences from LASIK. METHODS An intraocular pressure analytical model utilising fluid dynamics (simulating air puff) was developed using OpenFoam and Scilab. In addition, solid mechanics (simulating the deformation of the corneal structure) and a ray-tracing technique (simulating applanation detection) simulated by a previously established air-puff Tonovue tonometer were used to simulate post-SMILE and post-LASIK intraocular pressure. RESULTS Based on the proposed model, while at a myopic correction of zero dioptres the difference in intraocular pressure before and after SMILE was 0 mmHg, whereas the difference before and after LASIK was -2.2 mmHg. This trend was observed with a myopic correction up to 12 dioptres. CONCLUSION In a numerical simulation, differences in intraocular pressure in LASIK and SMILE largely resulted from the completeness of the Bowman's membrane resulting from cap or flap creation.
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Affiliation(s)
| | - Wai W Wang
- Crystalvue Medical Corporation, Taoyuan, Taiwan
| | | | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
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Spiru B, Kling S, Hafezi F, Sekundo W. Biomechanical Properties of Human Cornea Tested by Two-Dimensional Extensiometry Ex Vivo in Fellow Eyes: Femtosecond Laser-Assisted LASIK Versus SMILE. J Refract Surg 2018; 34:419-423. [PMID: 29889296 DOI: 10.3928/1081597x-20180402-05] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 04/02/2018] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the biomechanical properties of the ex vivo human cornea after flap-based versus cap-based laser refractive surgery in the same donor. METHODS In this experimental study, 11 pairs of human corneas unsuitable for transplantation were equally divided into two groups. Corneas from the right eye were treated with femtosecond laser-assisted LASIK (FSLASIK) and corneas from the left eye with small incision lenticule extraction (SMILE). Pachymetry was measured in each eye directly before laser refractive surgery. All corneas were subjected to a refractive correction of -10.00 diopters (D) sphere and -0.75 D cylinder at 0° with a 7-mm zone, using either a 110-μm flap (FS-LASIK) or 130-μm cap (SMILE). For two-dimensional biomechanical measurements, corneoscleral buttons underwent two testing cycles (preconditioning stress-strain curve from 0.03 to 9.0 N and stress-relaxation at 9.0 N during 120 sec) to analyze the elastic and viscoelastic material properties. The effective elastic modulus was calculated. Statistical analysis was performed with a confidence interval of 95%. RESULTS In stress-strain measurements, the effective elastic modulus was 1.47 times higher (P = .003) after SMILE (median = 8.22 [interquartile range = 4.76] MPa) compared to FS-LASIK (median = 5.59 [inter-quartile range = 2.77] MPa). The effect size was large (r = 0.83). No significant differences (P = .658) were observed among stress-relaxation measurements, with a mean remaining stress of 181 ± 31 kPa after SMILE and 177 ± 26 kPa after FS-LASIK after relaxation. CONCLUSIONS Compared to a flap-based procedure such as FS-LASIK, the SMILE technique can be considered superior in terms of biomechanical stability, when measured experimentally in ex vivo human fellow eye corneas. [J Refract Surg. 2018;34(6):419-423.].
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Damgaard IB, Reffat M, Hjortdal J. Review of Corneal Biomechanical Properties Following LASIK and SMILE for Myopia and Myopic Astigmatism. Open Ophthalmol J 2018; 12:164-174. [PMID: 30123381 PMCID: PMC6062908 DOI: 10.2174/1874364101812010164] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/08/2018] [Accepted: 01/20/2018] [Indexed: 11/22/2022] Open
Abstract
Worldwide, femtosecond Laser Assisted In-situ Keratomileusis (LASIK) is a well known and commonly used refractive technique, although Small Incision Lenticule Extraction (SMILE) has become increasingly popular since it was introduced in 2011. In LASIK, a corneal flap is cut with a microkeratome or femtosecond laser, followed by thinning of the stromal bed with excimer laser ablation. In SMILE, a minor intrastromal lenticule is cut with a femtosecond laser and subsequently removed through a small incision, leaving the anterior and strongest part of the cornea almost intact. Both LASIK and SMILE require cutting of corneal lamellae that may reduce the biomechanical stability of the cornea, with the potential risk of corneal iatrogenic ectasia as a severe complication. However, SMILE preserves the anterior corneal integrity and may, in theory, better preserve the corneal biomechanical strength than LASIK after surgery. A review aimed to examine the current literature that describes and compares the corneal biomechanical properties after Laser Assisted In-situ Keratomileusis (LASIK) and Small Incision Lenticule Extraction (SMILE). A comprehensive search was performed in Pubmed.gov using the following search queries: Corneal biomechanical properties, corneal biomechanics, ocular response analyser, ocular response analyzer, ORA, ex vivo, in vitro, Corvis, Corvis ST, LASIK, and SMILE.
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Affiliation(s)
- Iben Bach Damgaard
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Jesper Hjortdal
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
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Vanathi M. Advances in Cornea. Open Ophthalmol J 2018; 12:130-133. [PMID: 30123377 PMCID: PMC6062899 DOI: 10.2174/1874364101812010130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Artini W, B Riyanto S, Hutauruk JA, D Gondhowiardjo T, Kekalih A. Predictive Factors for Successful High Myopia Treatment Using High-Frequency Laser- In-Situ Keratomileusis. Open Ophthalmol J 2018; 12:214-225. [PMID: 30123384 PMCID: PMC6062894 DOI: 10.2174/1874364101812010214] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 05/18/2018] [Accepted: 07/05/2018] [Indexed: 11/22/2022] Open
Abstract
Aim To evaluate the predictive factors of LASIK procedure for high myopia with or without astigmatism using a combination of high-frequency femtosecond-assisted LASIK followed by an excimer laser. Methods This study was a retrospective interventional case series study to evaluate myopic eyes undergoing high platform LASIK with FEMTO LDV Z2 intervention, followed by WaveLight®EX500 excimer laser machine. Subjects were divided into 2 groups: high myopia (SE of -6.01 to -9.00 D) and very high myopia (SE of -9.01 D or higher). Myopic eyes (Spherical Equivalent/SE) less than -13 D were included in this study. Visual Acuity (VA) was evaluated 1 day and 60 days after the procedure. Predictive factors, such as age, degree of sphere, degree of astigmatism, keratometric reading and axial length were analyzed to detect any influences affecting the final VA results. Results A total of 316 myopia eyes underwent intervention, mean age: 25.3±3.8 years. Target treatment was achieved in 96.1% of patients with high myopia and 69.9% of patients with very high myopia. High degree of sphere and astigmatism constitutes an important factor influencing final VA. Conclusion Modern machines provide a more promising efficacy and success of LASIK procedure in high myopia: important predictive factors were a high degree of sphere and astigmatism for achieving the optimal final outcome.
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Affiliation(s)
- Widya Artini
- Department of Ophthalmology, Faculty of Medicine, Universitas Indonesia, Cipto Mangunkusumo Kirana Hospital, Jakarta, Indonesia.,Jakarta Eye Center Menteng Jakarta, Jakarta, Indonesia
| | | | | | - Tjahjono D Gondhowiardjo
- Department of Ophthalmology, Faculty of Medicine, Universitas Indonesia, Cipto Mangunkusumo Kirana Hospital, Jakarta, Indonesia.,Jakarta Eye Center Menteng Jakarta, Jakarta, Indonesia
| | - Aria Kekalih
- Community Medicine Department, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
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Chen X, Stojanovic A, Xu Y, Zhou W, Raeder S, Enayati S, Utheim TP. Medium- to Long-Term Results of Corneal Cross-Linking for Keratoconus Using Phototherapeutic Keratectomy for Epithelial Removal and Partial Stromal Ablation. J Refract Surg 2018; 33:488-495. [PMID: 28681909 DOI: 10.3928/1081597x-20170504-03] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 04/11/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the medium- to long-term outcomes of corneal cross-linking in treatment of keratoconus using transepithelial phototherapeutic keratectomy (PTK-CXL) for epithelial removal and partial stromal ablation to stabilize the cornea, reduce corneal irregularity, and improve corrected vision. METHODS Retrospective analysis of 46 keratoconic eyes that underwent PTK-CXL. Corrected distance visual acuity (CDVA), manifest refraction, steep and flat simulated keratometry (Kmax and Kmin), corneal irregularity index (IRI), corneal higher order aberrations (HOAs), epithelial thickness profile, and corneal biomechanical characteristics were evaluated preoperatively and postoperatively. RESULTS At a mean follow-up time of 21.0 ± 7.6 months (range: 10 to 43 months) postoperatively, CDVA improved from 0.25 ± 0.24 to 0.18 ± 0.22 logMAR (P = .002). CDVA remained unchanged in 32.6% (15 eyes) and 56.5% (26 eyes) gained up to five Snellen lines of CDVA, whereas 6.5% (3 eyes) lost two or more lines of CDVA, respectively. Postoperatively, flattening of Kmax from 50.58 ± 5.26 to 48.96 ± 4.00 diopters (D) and Kmin from 45.80 ± 3.11 to 44.77 ± 2.63 D (P < .001), reduction of IRI from 49.7 ± 24.5 to 43.4 ± 21.4 µm (P = .002), decrease of root mean square HOAs (at 5-mm diameter) from 2.66 ± 1.31 to 2.37 ± 1.37 µm (P = .037), and slight thickening of corneal epithelium were registered, whereas most of the corneal biomechanical measurements did not show statistically significant change. Two eyes demonstrated slight topographic regression. CONCLUSIONS PTK-CXL seems to be effective in arresting the progression of keratoconus, improving CDVA, flattening the cornea, regularizing corneal surface, and reducing corneal HOAs. [J Refract Surg. 2017;33(7):488-495.].
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Qin B, Li M, Chen X, Sekundo W, Zhou X. Early visual outcomes and optical quality after femtosecond laser small-incision lenticule extraction for myopia and myopic astigmatism correction of over -10 dioptres. Acta Ophthalmol 2018; 96:e341-e346. [PMID: 29251814 DOI: 10.1111/aos.13609] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 09/02/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE To investigate early visual and refractive outcomes, corneal stability and optical quality after femtosecond laser small-incision lenticule extraction (SMILE) for treating myopia and myopic astigmatism over -10 D. METHODS Thirty eyes (30 patients) with myopia and myopic astigmatism of over -10 D were treated with VisuMax® femtosecond laser (version 3.0; Carl Zeiss Meditec AG, Jena, Germany). Six months postoperative safety, efficacy and predictability were evaluated. Corneal Scheimpflug topography was measured preoperatively, 1 day, 3 months and 6 months postoperatively. Wavefront aberrations were measured preoperatively, 3 months and 6 months postoperatively. RESULTS Six months postoperatively, LogMAR uncorrected and corrected distance visual acuity (CDVA) were -0.013 ± 0.086 and -0.073 ± 0.069, respectively. 73% (97%) of eyes were within 0.5 (1) D of target refraction. No eyes lost CDVA, 43% (13 eyes) gained one line and 7% (two eyes) gained two lines. Mean corneal back curvature (KMB) and posterior central elevation (PCE) did not change significantly comparing preoperative and 6 months postoperative data (p = 0.91 and 0.77, respectively). Comparing 1 day with 6 months postoperative data, central corneal thickness (CCT), mean corneal front curvature (KMF), KMB and PCE did not change significantly (p = 0.27, 0.07, 0.52, 0.71, respectively). Total higher-order aberration (HOA), spherical aberration and coma increased significantly (p < 0.01) but trefoil remained stable (p = 0.49). CONCLUSION Our results indicate that SMILE can correct myopia and myopic astigmatism of over -10 D predictably. No early ectasia was observed. Long-term changes in visual quality and corneal stability require further investigation.
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Affiliation(s)
- Bing Qin
- Department of Ophthalmology; Myopia Key Laboratory of the Health Ministry; Eye and ENT Hospital of Fudan University; Shanghai China
| | - Meiyan Li
- Department of Ophthalmology; Myopia Key Laboratory of the Health Ministry; Eye and ENT Hospital of Fudan University; Shanghai China
| | - Xun Chen
- Department of Ophthalmology; Myopia Key Laboratory of the Health Ministry; Eye and ENT Hospital of Fudan University; Shanghai China
| | - Walter Sekundo
- Department of Ophthalmology; Philipps University of Marburg; Marburg Germany
| | - Xingtao Zhou
- Department of Ophthalmology; Myopia Key Laboratory of the Health Ministry; Eye and ENT Hospital of Fudan University; Shanghai China
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Wang L, Tian L, Huang Y, Huang Y, Zheng Y. Assessment of Corneal Biomechanical Properties with Inflation Test Using Optical Coherence Tomography. Ann Biomed Eng 2018; 46:247-256. [PMID: 29297099 DOI: 10.1007/s10439-017-1973-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 12/19/2017] [Indexed: 11/26/2022]
Abstract
Biomechanical properties are important for the cornea to maintain its normal shape and function. There is still a need to develop better methods for accurate measurement of corneal mechanical properties. In this study, we propose to introduce the optical coherence tomography (OCT) in inflation test for the imaging of corneal deformation in order to measure its biomechanical properties. Ten cornea-mimicking silicone phantoms with different stiffness and five fresh porcine corneas were tested using the proposed method. Intra-ocular pressure was changed from 10 to 90 mmHg using two different loading rates to observe the pressure-apex displacement relationship and calculate the apparent stiffness of the corneas. Stiffness of the corneal phantoms obtained by the inflation test ranged from 0.2 to 1 MPa, which was highly consistent with the results from the mechanical tensile test (y = 0.70x, p < 0.001). The porcine corneas showed highly viscoelastic behavior with obvious hysteresis in inflation. The apparent stiffness of the porcine corneas was 0.63 ± 0.07 and 1.05 ± 0.08 MPa with loading rates of 3.3 and 33 mmHg/min, respectively. Mapping of corneal surface displacement was also generated for both the phantom and porcine corneas. This study showed that it is feasible to incorporate the high resolution OCT imaging in inflation test to measure the biomechanical properties of the cornea.
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Affiliation(s)
- Like Wang
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Lei Tian
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory; National Engineering Research Center for Ophthalmology, Beijing, 100730, China
| | - Yanping Huang
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, 528000, China.
| | - Yifei Huang
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Yongping Zheng
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
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MOSHIRFAR M, SHAH TJ, MASUD M, FANNING T, LINN SH, RONQUILLO Y, HOOPES PCSR. A Modified Small-Incision Lenticule Intrastromal Keratoplasty (sLIKE) for the Correction of High Hyperopia: A Description of a New Surgical Technique and Comparison to Lenticule Intrastromal Keratoplasty (LIKE). MEDICAL HYPOTHESIS, DISCOVERY & INNOVATION OPHTHALMOLOGY JOURNAL 2018; 7:48-56. [PMID: 30250852 PMCID: PMC6146242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Patients with high hyperopia are generally confined to either spectacle wear or contact lenses as a primary means of refractive correction. For this patient population, the surgical corrective methods, such as hyperopic laser assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are imperfect options due to induction of higher-order aberrations, optical regression, and loss of best corrected distance visual acuity. Recently, there has been growing interest in lenticule implantation underneath a flap via lenticule intrastromal keratoplasty (LIKE) for high hyperopia correction (+3 diopters to +10 diopters). We instead propose a modified surgical technique (small-incision lenticule intrastromal keratoplasty, sLIKE), in which the lenticule is implanted inside an intrastromal pocket thereby causing less injury to the subbasal nerve plexus injury, less postoperative dry eye symptoms, less reduction in biomechanical strength, and lower chances for epithelial ingrowth. We provide an overview of these novel surgical techniques to treat high hyperopia, and compare the associated advantages and disadvantages. In addition, we will discuss the enhancement options and methods of optimization for both surgical techniques.
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Affiliation(s)
- Majid MOSHIRFAR
- John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, School of Medicine, University of Utah, United States
- Utah Lions Eye Bank, Murray, UT, United States
- HDR Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT 84020, United States
| | - Tirth J. SHAH
- Department of Ophthalmology, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, United States
| | - Maliha MASUD
- University of Utah, Salt Lake City, Utah, United States
| | - Trey FANNING
- HDR Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT 84020, United States
| | - Steven H. LINN
- HDR Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT 84020, United States
| | - Yasmyne RONQUILLO
- HDR Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT 84020, United States
| | - Phillip C. SR HOOPES
- HDR Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT 84020, United States
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Siedlecki J, Luft N, Kook D, Wertheimer C, Mayer WJ, Bechmann M, Wiltfang R, Priglinger SG, Sekundo W, Dirisamer M. Enhancement After Myopic Small Incision Lenticule Extraction (SMILE) Using Surface Ablation. J Refract Surg 2017; 33:513-518. [DOI: 10.3928/1081597x-20170602-01] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/16/2017] [Indexed: 11/20/2022]
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Jin HY, Wan T, Wu F, Yao K. Comparison of visual results and higher-order aberrations after small incision lenticule extraction (SMILE): high myopia vs. mild to moderate myopia. BMC Ophthalmol 2017; 17:118. [PMID: 28683793 PMCID: PMC5501544 DOI: 10.1186/s12886-017-0507-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/22/2017] [Indexed: 11/21/2022] Open
Abstract
Background To compare the refractive results and higher-order aberrations (HOAs) after small incision lenticule extraction (SMILE) in high myopia and mild to moderate myopia patients. Methods This prospective study included 165 eyes (86 patients) undergoing SMILE. According to the preoperative spherical equivalent (SE), treated eyes were divided into two groups: the high myopia group (more than -6.0 D, group-H) and the mild to moderate group (less than -6.0 D, group-M). Follow-up intervals were at 1 day, 10 days, 1 month and 3 months postoperatively. We obtained the following parameters: uncorrected (UDVA) and corrected distance visual acuity (CDVA), SE, efficacy and safety index, and HOAs. Results Preoperative SE was -7.16 ± 0.93 D in group-H and -4.34 ± 0.97 D in group-M. At 3 months postoperatively, the SE in group-H and group-M was -0.20 ± 0.37 D and 0.01 ± 0.19 D (t = - 4.11, P<0.05), respectively. It was found that 77% and 98% had an UDVA of 20/20, 98% and 99% had a CDVA of 20/20 in group-H and group-M, respectively, while 87% and 95% had a SE within ±0.5 D and ±1.0 D in group-H, and 98% and 100% in group-M. The efficacy indexes were 0.98 ± 0.18 in group-H and 1.05 ± 0.10 in group-M (t = - 3.084, p < 0.05). The safety indexes were 1.06 ± 0.09 and 1.06 ± 0.09 (t = 0.153, p > 0.05), respectively. There were significant increases in total HOAs, 3rd-order coma, and 4th-order spherical aberrations. Conclusions SMILE is an effective and safe surgery for correcting myopia. But the target correction amount in high myopia patients should be adjusted to avoid undercorrection and acquired more satisfaction. SMILE induced increases of HOAs. Trial registration ChiTrial registration number: ChiCTR-OON-16009164. Retrospectively registered: 06.September.2016
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Affiliation(s)
- Hong-Ying Jin
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Ting Wan
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Fang Wu
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Ke Yao
- Eye Center, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310009, China.
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Shen Y, Su X, Liu X, Miao H, Fang X, Zhou X. Changes in intraocular pressure values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology tonometer (CST) in the early phase after small incision lenticule extraction (SMILE). BMC Ophthalmol 2016; 16:205. [PMID: 27863469 PMCID: PMC5116167 DOI: 10.1186/s12886-016-0381-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/04/2016] [Indexed: 04/26/2023] Open
Abstract
Background Corneal biomechanical properties are always compromised after corneal refractive surgeries thus leading to underestimated intraocular pressure (IOP) that complicates the management of IOP. We investigated the changes in postoperative baseline of IOP values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology (CST) in the early phase after small incision lenticule extraction (SMILE). Methods Twenty-two eyes (−6.76 ± 1.39D) of 22 moderate and high myopes, (28.36 ± 7.14 years, 12 male and 10 female) were involved in this prospective study. IOP values were measured using a non-contact tomometer (NCT-IOP), an ocular response analyzer (corneal-compensated IOP, IOPcc and Goldmann-correlated IOP, IOPg) and a Corvis scheimpflug technology tonometer (CST-IOP) preoperatively, at 20 min and 24 h, postoperatively. Repeated measures analysis of variance (RM-ANOVA), Pearson’s correlation analysis and multiple linear regression models (stepwise) were performed. Cut-off P values were 0.05. Results Except for IOPcc, NCT-IOP, IOPg, and CST-IOP values significantly decreased after SMILE procedure (All P values <0.05). ΔCCT, as well as ΔMRSE and ΔKm, did not significantly correlated with ΔNCT-IOP, ΔIOPcc, ΔIOPg or ΔCST-IOP, (all P values >0.05). Multiple linear regression models (stepwise) showed that the practical post-operative IOP value was the main predictor of the theoretical post-operative NCT-IOP, IOPcc and IOPg values (all P values <0.001). The postoperative applanation time 1 (AT1) value (B = 8.079, t = 4.866, P < 0.001), preoperative central corneal thickness (CCT) value (B = 0.035, t = 2.732, P = 0.014) and postoperative peak distance (PD) value (B = 0.515, t = 2.176, P = 0.043) were the main predictors of the theoretical post-operative CST-IOP value. Conclusions IOP values are underestimated when assessed after SMILE by using NCT-IOP, IOPg and CST-IOP. The practical postoperative IOPcc value and theoretical post-operative CST-IOP value may be more preferable for IOP assessment in the early phase after SMILE. Trial registration Current Controlled Trials ChiCTRONRC13003114. Retrospectively registered 17 March 2013
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Affiliation(s)
- Yang Shen
- Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China.,Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China
| | - Xiangjian Su
- Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China
| | - Xiu Liu
- Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China
| | - Huamao Miao
- Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China.,Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China
| | - Xuejun Fang
- Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China.
| | - Xingtao Zhou
- Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China. .,Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China.
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