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Pérez-Corral J, Cardona G, Piñero DP, Barroso D, Armadans L. Short- and mid-term changes in CORVIS ST parameters in successful, adult orthokeratology patients. Clin Exp Optom 2023; 106:726-733. [PMID: 36375143 DOI: 10.1080/08164622.2022.2140031] [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: 03/27/2022] [Revised: 07/12/2022] [Accepted: 10/20/2022] [Indexed: 11/16/2022] Open
Abstract
CLINICAL RELEVANCE The changes in various biomechanical and tomographic characteristics of the cornea associated with orthokeratology may allow us to identify potential mid- and long-term structural alterations, resulting in a better understanding of the governing mechanisms of this procedure and in its optimisation. BACKGROUND The study aimed at describing short and mid-term changes in CORVIS ST® parameters and indices in orthokeratology (ortho-k), and their diurnal variations. METHODS A prospective observational study was designed in which several CORVIS ST® parameters of 75 new adult participants successfully fitted with overnight ortho-k Seefree® (Conóptica - Hecht Contactlinsen) contact lenses were explored. Measurements were conducted in baseline (BL) conditions and in the morning and evening at the one-night (1 NM/1NT), one-week (1WM/1 WT) and 3-month (3 MM/3MT) follow-up visits. RESULTS Statistically significant differences were found in DARatio_2 mm, IntRad, ARTh, CBI and TBI following overnight ortho-k, when compared with BL values, with most values reaching stability at 1WM or reverting to BL values at 3 MM. The ARTh and CBI parameters showed some of the most significant temporal variations (both p < 0.001), probably reflecting the encountered differences in central corneal thickness between BL and 1WM (p = 0.010) and between BL and 3 MM (p = 0.016). In general, corneal rigidity was higher in the morning at all follow-up visits, and decreased during the day. No statistically significant changes in adjusted intraocular pressure values were found. CONCLUSION Ortho-k in adults may be considered a safe procedure in terms of short and mid-term changes in CORVIS ST® parameters. The observed alterations in most of the parameters provided by the Corvis ST® probably responded to the well-described changes in corneal pachymetry and tomography, rather than to actual alterations in corneal rigidity.
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Affiliation(s)
- Joan Pérez-Corral
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - Genis Cardona
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - David Barroso
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - Laura Armadans
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
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He Y, Ma BS, Zeng JH, Ma DJ. Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery. Front Bioeng Biotechnol 2023; 11:1144455. [PMID: 37091331 PMCID: PMC10117965 DOI: 10.3389/fbioe.2023.1144455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused.
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Affiliation(s)
- Ye He
- Changsha Aier Eye Hospital, Changsha, China
| | - Bo-Sheng Ma
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jun-Hao Zeng
- Xiangya School of Medicine, Central South University, Changsha, China
| | - Dai-Jin Ma
- Changsha Aier Eye Hospital, Changsha, China
- *Correspondence: Dai-Jin Ma,
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Li N, Chen T, Tian G, Lin Y, Meng Y, Gao H, Liu M. Changes in aberrations and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in eyes with high astigmatism: a retrospective case control study. BMC Ophthalmol 2023; 23:62. [PMID: 36782180 PMCID: PMC9923895 DOI: 10.1186/s12886-023-02809-4] [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] [Accepted: 02/06/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND To compare the 6-month changes in aberration and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for high astigmatism. METHODS In this retrospective case control study, 47 eyes with high astigmatism (≥ 2.5 D, HA group) and 47 eyes with low astigmatism (≤ 1.0 D, LA group) underwent FS-LASIK. Preoperative and follow-up examinations included visual outcomes, higher order aberrations (HOAs) and biomechanics. Biomechanical parameters include a deformation amplitude ratio of 2 mm (DA ratio 2 mm), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), and ambrosio relational thickness through the horizontal meridian (ARTh). RESULTS Six months postoperatively, there was no significant difference in the efficacy and safety index (both P > 0.05) between the two groups, but the cylinder was higher in the HA group. The HOAs increased significantly after surgery in both groups (all P < 0.05). Six months postoperatively, the changes in spherical aberration and HOAs were larger in the HA group (both P < 0.005), but there was no significant difference between the changes in coma (P > 0.05). Significant decreases in SP-A1 and ARTh and significant increases in the IIR and DA ratio of 2 mm (all P < 0.05) were observed after surgery in both groups. The changes in the DA ratio 2 mm, IIR, SP-A1, and ARTh were not significantly different between the groups. CONCLUSION FS-LASIK had relative comparable efficacy and safety in correcting high and low myopic astigmatism, with higher astigmatic under-correction in eyes with high astigmatism. High astigmatism in eyes after FS-LASIK could introduce larger corneal aberrations, but the impact on corneal stiffness was the same as that in eyes with low astigmatism.
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Affiliation(s)
- Na Li
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Tong Chen
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Ge Tian
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Yue Lin
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Yuan Meng
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Hua Gao
- grid.490473.dEye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021 Jinan, China ,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021 Jinan, China ,grid.410638.80000 0000 8910 6733School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021 Jinan, China
| | - Mingna Liu
- Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), 372 Jingsi Road, 250021, Jinan, China. .,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, 372 Jingsi Road, 250021, Jinan, China. .,School of Ophthalmology, Shandong First Medical University, 372 Jingsi Road, 250021, Jinan, China.
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Gao W, Zhao X, Wang Y. Change in the corneal material mechanical property for small incision lenticule extraction surgery. Front Bioeng Biotechnol 2023; 11:1034961. [PMID: 36890912 PMCID: PMC9986312 DOI: 10.3389/fbioe.2023.1034961] [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: 09/02/2022] [Accepted: 02/10/2023] [Indexed: 02/22/2023] Open
Abstract
Purpose: To assess the distribution characteristics and related factors of stress-strain index (SSI) values and discuss changes in biomechanical parameters, including SSI, after small incision lenticule extraction (SMILE) surgery. Methods: This study included 253 patients who underwent SMILE (253 eyes). SSI and other biomechanical parameters were measured using corneal visualization Scheimpflug technology before and 3 months after surgery. The data collected included SSI, central corneal thickness (CCT), and eight other dynamic corneal response parameters. The Kolmogorov-Smirnov test, Pearson and partial correlation analyses, and paired-sample t-tests were used for statistical analyses. Results: Both pre-op SSI and ΔSSI follow a normal distribution, while post-op SSI does not follow a normal distribution. The decline in SSI after SMILE surgery was not statistically significant, and the data dispersion of SSI after SMILE surgery was close to that before surgery (p > 0.05). No statistical correlation was noted between SSI values and age and pre-op CCT (all p > 0.05). However, both pre- and post-op SSI values decreased with increasing degree of myopia (all p < 0.05), and weakly correlated with preoperative intraocular pressure and biomechanically corrected intraocular pressure (all p < 0.05). Other biomechanical parameters changed significantly after surgery (all p < 0.001). After SMILE, the magnitude of the deformation at the highest concave, deformation ratio, and integral radius increased significantly (all p < 0.001), while the Ambrosio relational thickness horizontal, stiffness parameter A1, and Corvis biomechanical index decreased significantly (p < 0.001). Conclusion: SSI, which reflects essential corneal material attributes, differs from other corneal biomechanical parameters and remains stable before and after SMILE surgery, and can be used as an indicator to evaluate changes in corneal material properties after SMILE surgery.
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Affiliation(s)
- Wenjing Gao
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye Hospital, Tianjin, China.,Nankai University Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, Tianjin, China
| | - Xinheng Zhao
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye Hospital, Tianjin, China.,Nankai University Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, Tianjin, China
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye Hospital, Tianjin, China.,Nankai University Eye Institute, Nankai University Affiliated Eye Hospital, Nankai University, Tianjin, China
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Clinical Evaluation of Corneal Biomechanics following Laser Refractive Surgery in Myopic Eyes: A Review of the Literature. J Clin Med 2022; 12:jcm12010243. [PMID: 36615041 PMCID: PMC9821300 DOI: 10.3390/jcm12010243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/18/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
The role of corneal biomechanics in laser vision correction (LVC) is currently being raised in the assessment of postoperative corneal ectasia risk. The aim of the paper was to evaluate the changes in corneal biomechanics after LVC procedures based on a systematic review of current studies. The results of a search of the literature in the PubMed, Science Direct, Google Scholar, and Web of Science databases were selected for final consideration according to the PRISMA 2020 flow diagram. Included in our review were 17 prospective clinical studies, with at least 6 months of follow-up time. Corneal biomechanical properties were assessed by Ocular Response Analyzer (ORA), or Corvis ST. The results of the study revealed the highest corneal biomechanics reduction after laser in situ keratomileusis (LASIK) followed by small incision lenticule extraction (SMILE) and surface procedures, such as photorefractive keratectomy (PRK) or laser-assisted sub-epithelial keratectomy (LASEK). In SMILE procedure treatment planning, the use of thicker caps preserves the corneal biomechanics. Similarly, reduction of flap thickness in LASIK surgery maintains the corneal biomechanical strength. Future prospective clinical trials with standardization of the study groups and surgical parameters are needed to confirm the results of the current review.
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Zhao Y, Hu G, Yan Y, Wang Z, Liu X, Shi H. Biomechanical analysis of ocular diseases and its in vitro study methods. Biomed Eng Online 2022; 21:49. [PMID: 35870978 PMCID: PMC9308301 DOI: 10.1186/s12938-022-01019-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 07/13/2022] [Indexed: 12/25/2022] Open
Abstract
Ocular diseases are closely related to the physiological changes in the eye sphere and its contents. Using biomechanical methods to explore the relationship between the structure and function of ocular tissue is beneficial to reveal the pathological processes. Studying the pathogenesis of various ocular diseases will be helpful for the diagnosis and treatment of ocular diseases. We provide a critical review of recent biomechanical analysis of ocular diseases including glaucoma, high myopia, and diabetes. And try to summarize the research about the biomechanical changes in ocular tissues (e.g., optic nerve head, sclera, cornea, etc.) associated with those diseases. The methods of ocular biomechanics research in vitro in recent years are also reviewed, including the measurement of biomechanics by ophthalmic equipment, finite element modeling, and biomechanical analysis methods. And the preparation and application of microfluidic eye chips that emerged in recent years were summarized. It provides new inspiration and opportunity for the pathogenesis of eye diseases and personalized and precise treatment.
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