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Fu D, Zhao Y, Zhou X. Corneal Biomechanical Properties after Small Incision Lenticule Extraction Surgery on Thin Cornea. Curr Eye Res 2020; 46:168-173. [PMID: 32643431 DOI: 10.1080/02713683.2020.1792507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To explore the biomechanical changes in thin corneas after the small incision lenticule extraction (SMILE) surgery. METHODS This prospective survey screened patients scheduled for the SMILE surgery from November 2017 to March 2018. Patients with thin corneas (central corneal thickness [CCT] ≤500 μm) and those with normal corneal thickness (CCT > 500 μm) were enrolled. Corneal biomechanics were examined by the ocular response analyser and Corvis ST, preoperatively and at 1 day, 3 weeks, and 3 months postoperatively. RESULTS Twenty-seven patients (46 eyes) with mean spherical equivalent of -5.1 ± 1.7 D were assigned to the thin cornea group, and 28 (45 eyes) cases with mean spherical equation of -5.3 ± 1.8 D were assigned to the control group. Safety and efficacy did not differ between the two age- and refraction-matched groups (safety index, 1.15 ± 0.14 vs 1.14 ± 0.17 [P = .7]; efficacy index, 1.11 ± 0.13 vs 1.16 ± 0.22 [P = .2]). All biomechanical parameters changed significantly after SMILE. The thin cornea group showed less decrease in the second applanation time (A2 Time), stiffness parameters at first applanation (SP-A1). Pooling data from two groups, lower CCT was correlated with less A2 Time change (r = 0.37, P < .01) and less SP-A1 change (r = -0.33, P < .01). Less bIOP change was correlated with higher residual stromal thickness index and thicker CCT (P = .003, R2 = 0.12). CONCLUSION Over a short-term observation period, less corneal biomechanic deterioration may have contributed to the safety of SMILE on thin cornea.
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Affiliation(s)
- Dan Fu
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University , Shanghai, China.,NHC Key Laboratory of Myopic (Fudan University) , Shanghai, China.,Shanghai Research Centre of Ophthalmology and Optometry , Shanghai, China
| | - Yu Zhao
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University , Shanghai, China.,NHC Key Laboratory of Myopic (Fudan University) , Shanghai, China.,Shanghai Research Centre of Ophthalmology and Optometry , Shanghai, China
| | - Xingtao Zhou
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University , Shanghai, China.,NHC Key Laboratory of Myopic (Fudan University) , Shanghai, China.,Shanghai Research Centre of Ophthalmology and Optometry , Shanghai, China
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M Kouhani MH, Wu J, Tavakoli A, Weber AJ, Li W. Wireless, passive strain sensor in a doughnut-shaped contact lens for continuous non-invasive self-monitoring of intraocular pressure. LAB ON A CHIP 2020; 20:332-342. [PMID: 31825423 DOI: 10.1039/c9lc00735k] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
After cataract, glaucoma is the second leading cause of blindness worldwide and real-time monitoring of intraocular pressure (IOP) is of great demand. We present a wireless, passive sensor sitting inside a customized, planar and circular doughnut-shaped contact lens capable of continuous monitoring of the change in the curvature of cornea caused by IOP fluctuations. The sensor consists of a constant capacitor and a variable inductor in the form of a stretchable, closed-loop, serpentine wire that serves as both the sensor and the antenna. Results show a pressure responsivity of 523 kHz per 1% axial strain on a pressurized polydimethylsiloxane membrane and 35.1 kHz per 1 mmHg change in the IOP of a canine eye. The sensor is tested for stability and shows unvaried characteristics after repeated cycles and parasitic movements. Predictable influences of temperature and humidity on the sensor response are also verified experimentally, which can be canceled out using real-time calibration with temperature and humidity sensors to integrate with a reader device. The design reported here has numerous advantages, such as design simplicity, component reliability, high responsivity, and low cost, thereby opening up potential opportunities for the translation of this non-invasive, continuous IOP monitoring technique into clinical applications.
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Affiliation(s)
- M Hossein M Kouhani
- Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI, USA.
| | - Jiajia Wu
- Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI, USA.
| | - Arman Tavakoli
- Department of Mathematics, Michigan State University, East Lansing, MI, USA
| | - Arthur J Weber
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Wen Li
- Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI, USA.
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Bueno-Gimeno I, Martínez-Albert N, Gené-Sampedro A, España-Gregori E. Anterior Segment Biometry and Their Correlation with Corneal Biomechanics in Caucasian Children. Curr Eye Res 2018; 44:118-124. [PMID: 30346843 DOI: 10.1080/02713683.2018.1539181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE To assess the relationship between the corneal biomechanical parameters and the anterior segment parameters in Caucasian children. METHODS This study included 293 eyes from 293 healthy children aged between 6 and 17 years. Corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer, axial length (AL) with IOLMaster and the anterior segment with Pentacam. Anterior segment parameters obtained were the following: central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and mean anterior and posterior keratometry. Two multiple linear regression models were constructed to assess the association between CH and CRF with anterior segment parameters. A value of p < 0.05 was taken as the criterion for statistical significance in all analyses. RESULTS The mean CH and CRF were 12.12 ± 1.71 and 12.30 ± 1.89 mmHg, respectively. Multiple linear regression revealed that CH and CRF were associated negatively with AL in both models, and positively with CCT and CV in the first and second model, respectively. Meanwhile ACD, ACV or mean keratometry did not correlated with CH and CRF. Moreover, when CCT was in the model, it explained more variability for both CH (22.1%) and CRF (30.9%) than when CV was included (16.2% for CH and 16.5% for CRF). CONCLUSIONS CH and CRF were correlated positively with CCT and CV, and negatively with AL in healthy Caucasian children. Moreover, corneal parameters were the most contributory variables to CH and CRF changes.
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Affiliation(s)
| | - Noelia Martínez-Albert
- a Department of Optics and Optometry and Vision Sciences , University of Valencia , Spain
| | - Andrés Gené-Sampedro
- a Department of Optics and Optometry and Vision Sciences , University of Valencia , Spain
| | - Enrique España-Gregori
- b Department of Surgery , University of Valencia , Spain.,c University Hospital La Fe , Spain
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Aoki S, Murata H, Nakakura S, Nakao Y, Matsuura M, Kiuchi Y, Asaoka R. Correlation between elastic energy stored in an eye and visual field progression in glaucoma. PLoS One 2018; 13:e0204451. [PMID: 30240430 PMCID: PMC6150541 DOI: 10.1371/journal.pone.0204451] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/07/2018] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To investigate whether the elastic energy stored in an eyeball at highest concavity (highest concavity energy; HCE), calculated with Corivs ST (CST, OCULUS), correlates with glaucomatous visual field (VF) progression. METHODS 108 eyes from 70 primary open angle-glaucoma patients were studied. The HCE was calculated using CST parameters. For each eye, the mean total deviation (mTD) of the 52 test points in the 24-2 Humphrey Field Analyzer test pattern was calculated and the mTD progression rate was determined from eight reliable VFs. Eyes were subdivided into: subgroups with low- or high-whole eye motion maximal length (WEM-d) and subgroups with short- or long-time taken to reach WEM-d (WEM-t), as measured with CST. The associations between mTD progression rate and HCE and other ocular/systemic parameters including age, Goldmann applanation tonometry based-intraocular pressure [GAT-IOP], and corneal hysteresis [CH] from the Ocular Response Analyzer (ORA®, Reichert) were investigated using the linear mixed model. The optimal model to describe mTD progression rate was selected from all possible combinations according to the second order bias corrected Akaike Information Criterion index. RESULTS Optimal models to describe mTD progression rate included: CH in the model for all eyes, age and HCE in the model for the WEM-d low group, HCE in the model for the WEM-t short group, mean GAT-IOP in the model for the WEM-d high group, and age in the model for the WEM-t long-group. CONCLUSIONS HCE was associated with glaucomatous VF progression in eyes with minimal whole eye motion (low WEM-d and WEM-t subgroups).
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Affiliation(s)
- Shuichiro Aoki
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
- Department of Ophthalmology, Sapporo City General Hospital, Sapporo, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Hyogo, Japan
| | - Yoshitaka Nakao
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
| | - Masato Matsuura
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
- Orthopic and Visual Science, Department of Rehabilitation, School of Allied Health Sciences, Kitasato University, Kanagawa, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
| | - Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
- * E-mail:
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Gobeka H, Barut Selver Ö, Palamar Onay M, Eğrilmez S, Yağcı A. Corneal Biomechanical Properties of Keratoconic Eyes Following Penetrating Keratoplasty. Turk J Ophthalmol 2018; 48:171-177. [PMID: 30202612 PMCID: PMC6126104 DOI: 10.4274/tjo.79664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 01/03/2018] [Indexed: 12/01/2022] Open
Abstract
Objectives To investigate the corneal biomechanical properties of keratoconic eyes following penetrating keratoplasty (PKP). Materials and Methods Thirty-five patients (70 eyes) were enrolled to this prospective study. Operated and contralateral keratoconic eyes were defined as Group 1 and 2, respectively. All patients underwent ophthalmological examination and measurements of corneal biomechanical properties by Ocular Response Analyzer (ORA), intraocular pressure (IOP) by Goldmann applanation tonometry, and central corneal thickness (CCT) by Pentacam. Shapiro-Wilk W test was performed to test normality of the data. The statistical significance was evaluated with the paired t-test and Wilcoxon signed ranks test. Pearson correlation and Spearman rho tests were used for correlation analysis. Results The average age and male/female ratio were 31.34±11.65 (15-60) years and 21/14, respectively. The mean values of the data obtained from Group 1 and 2 respectively were: corneal hysteresis (CH): 9.35±1.66, 8.18±1.84 mmHg (p=0.013), corneal resistance factor (CRF): 9.48±1.96, 7.14±2.05 mmHg (p<0.001), IOPcc: 16.90±4.32, 14.26±3.69 mmHg (p=0.004), IOPg: 15.45±4.61, 10.91±3.97 mmHg (p<0.001), IOPapl: 14.26±3.11, 13.09±2.54 mmHg (p=0.046), and central corneal thickness (CCT): 545.64±60.82, 442.60±68.14 μM (p<0.001). The positive correlation between CH and CRF was moderate (r=0.444) in Group 1 and strong (r=0.770) in Group 2. There was a moderate negative correlation between CH and IOPcc in both groups (r=-0.426, r=-0.423), but CH was not correlated with IOPg or IOPapl in either group. There were weak to strong positive correlations between CRF and all IOP values in both groups. There was no correlation between CRF and CCT in Group 1 (r=0.075) and a very weak correlation in Group 2 (r=0.237). Only IOPcc and IOPg were strongly correlated in both groups. Conclusion Better understanding of corneal biomechanical properties is essential for elucidating the pathophysiology and diagnosis of several corneal pathologies such as keratoconus. The biomechanical properties of keratoconic eyes seem to be closer to normal values after PKP.
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Affiliation(s)
- Hamidu Gobeka
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Özlem Barut Selver
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Melis Palamar Onay
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Sait Eğrilmez
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Ayşe Yağcı
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
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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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Aoki S, Murata H, Matsuura M, Fujino Y, Nakakura S, Nakao Y, Kiuchi Y, Asaoka R. The effect of air pulse-driven whole eye motion on the association between corneal hysteresis and glaucomatous visual field progression. Sci Rep 2018; 8:2969. [PMID: 29445204 PMCID: PMC5813173 DOI: 10.1038/s41598-018-21424-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/05/2018] [Indexed: 11/30/2022] Open
Abstract
Corneal hysteresis (CH) measured with Ocular Response Analyzer (Reichert: ORA) has been reported to be closely related to the glaucomatous visual field (VF) progression. The air pulse applied to an eye not only induces corneal deformation, but also whole eye motion (WEM), which may result in an inaccurate measurement of CH. Here we investigated the influence of air pulse-driven WEM measured with the Corivs ST (CST®, OCULUS) on the relationship between CH and VF progression in primary open angle-glaucoma patients. Using the CST parameters of the maximal WEM displacement (WEM-d) and the time to reach that displacement (WEM-t), the eyes were classified into subgroups (WEM-d low- and high-group, and WEM-t short- and long-group). For the whole population and all subgroups, the optimal linear mixed model to describe mean of total deviation (mTD) progression rate with eight reliable VFs was selected from all combinations of seven parameters including CH. As a result, optimal models for the mTD progression rate included CH in the whole population, the WEM-d low- group and the WEM-t short-group, but not in the WEM-d high-group and the WEM-t long-group. Our findings indicated association between CH and glaucomatous progression can be weakened because of large WEM.
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Affiliation(s)
- Shuichiro Aoki
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Masato Matsuura
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan.,Department of Rehabilitation, Orthopic and Visual Science, School of Allied Health Sciences, Kitasato University, Tokyo, Kanagawa, Japan
| | - Yuri Fujino
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Yoshitaka Nakao
- Department of Ophthalmology and Visual Sciences, Hiroshima University, Higashihiroshima, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Sciences, Hiroshima University, Higashihiroshima, Japan
| | - Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan.
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Corneal Biomechanical Changes After Trabeculectomy and the Impact on Intraocular Pressure Measurement. J Glaucoma 2017; 26:278-282. [PMID: 27977478 DOI: 10.1097/ijg.0000000000000595] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate corneal biomechanical changes induced by trabeculectomy and their impact on intraocular pressure (IOP) measurements. MATERIALS AND METHODS In total, 35 eyes of 35 consecutive glaucoma patients undergoing first-time trabeculectomy with mitomycin C were enrolled in this prospective interventional case series. Goldmann applanation tonometry (GAT) IOP, central corneal thickness, axial length, and Ocular Response Analyzer measurements [Goldmann-correlated IOP (IOPg), corneal-compensated IOP (IOPcc), corneal hysteresis (CH), and corneal resistance factor (CRF)] were assessed before and 6 months after uncomplicated trabeculectomy. Linear mixed models were used to compare the parameters before and after surgery. RESULTS IOP, central corneal thickness, and axial length showed a strong correlation with CH and CRF preoperatively and postoperatively. After adjusting for these influencing factors, CH changed from 7.75±1.46 to 7.62±1.66 mm Hg (P=0.720) and CRF from 8.67±1.18 to 8.52±1.35 mm Hg (P=0.640) after trabeculectomy, but these changes were not statistically significant. IOP decreased statistically significantly with all IOP measurements (P=0.001). IOPcc was statistically significantly higher than GAT (4.82±5.24 mm Hg; P=0.001) and IOPg (2.92±1.74 mm Hg; P=0.001) preoperatively and postoperatively (GAT, 3.29±3.36 mm Hg; P=0.001; IOPg, 3.35±1.81 mm Hg; P=0.001). The difference between IOPcc and GAT (P=0.5) and IOPcc and IOPg (P=0.06) did not change significantly before or after trabeculectomy. CONCLUSIONS Despite a marked IOP reduction and a possible weakening of the ocular walls after trabeculectomy, corneal structural tissue properties are not altered, and therefore, the accuracy of IOP measurements is not changed postoperatively. It seems likely, however, that Goldmann-correlated IOP measurements are underestimated in glaucoma patients before and after surgery.
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Pillunat KR, Spoerl E, Terai N, Pillunat LE. Effect of selective laser trabeculoplasty on corneal biomechanics. Acta Ophthalmol 2016; 94:e501-4. [PMID: 26749244 DOI: 10.1111/aos.12947] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 11/05/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE To evaluate the effect of selective laser trabeculoplasty (SLT) on ocular biomechanics as measured with the ocular response analyzer (ORA, AMETEK Inc. and Reichert Inc.). METHODS In a prospective case series, 52 eyes of 52 patients (aged 66.6 ± 9.6 years) with insufficient intraocular pressure (IOP) control despite maximum tolerated medical therapy underwent SLT (Solo(™) SLT, Ellex Inc.) for further IOP reduction. Goldmann-correlated IOP (IOPg), corneal-compensated IOP (IOPcc), corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with the ORA prior to and at least 4 weeks following SLT. RESULTS IOPg decreased statistically significantly from 18.0 ± 6.4 to 14.8 ± 3.8 mmHg and IOPcc from 20.2 ± 6.5 to 16.7 ± 3.4 mmHg (p < 0.001). CH increased from 8.53 ± 2.03 to 9.12 ± 1.83 mmHg (p = 0.028) and CRF decreased from 9.58 ± 2.18 to 9.1 ± 2.1 mmHg (p = 0.037), which was statistically significant. Correcting the CH and CRF data for the influence of IOP reduction with a covariance analysis, however, resulted in an unchanged CH (IOPg adjusted: p = 0.318; IOPcc adjusted: p = 0.468) and CRF (IOPg adjusted: p = 0.320; IOPcc adjusted: p = 0.464) after SLT. CONCLUSION Selective laser trabeculoplasty does not change corneal biomechanical properties as measured with the ORA in already pretreated patients with glaucoma. The measured increase in CH and decrease in CRF can be solely explained by IOP reduction.
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Affiliation(s)
- Karin R. Pillunat
- Department of Ophthalmology; University Hospital Carl Gustav Carus; TU Dresden Germany
| | - Eberhard Spoerl
- Department of Ophthalmology; University Hospital Carl Gustav Carus; TU Dresden Germany
| | - Naim Terai
- Department of Ophthalmology; University Hospital Carl Gustav Carus; TU Dresden Germany
| | - Lutz E. Pillunat
- Department of Ophthalmology; University Hospital Carl Gustav Carus; TU Dresden Germany
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Pillunat KR, Hermann C, Spoerl E, Pillunat LE. Analyzing biomechanical parameters of the cornea with glaucoma severity in open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2016; 254:1345-51. [PMID: 27118038 DOI: 10.1007/s00417-016-3365-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/14/2016] [Accepted: 04/19/2016] [Indexed: 11/29/2022] Open
Abstract
PURPOSE The purpose was to investigate a possible association of corneal hysteresis (CH) and corneal resistance factor (CRF) with open-angle glaucoma and the severity of disease. METHODS In this prospective cross-sectional study we recruited 86 open-angle glaucoma patients, 16 patients with ocular hypertension (OHT,) and 44 age-matched controls. Each participant had a complete glaucoma workup including measurements with the Ocular Response Analyzer and computerized perimetry with the Humphrey 30-2 SITA Standard program. Visual field damage was based on mean deviation (MD) and considered as early glaucomatous with a MD > - 6 dB, moderate glaucomatous between -6 and -12 dB and advanced glaucomatous < -12 dB. The association between ORA parameters, glaucoma, and disease severity was evaluated using univariate and multivariate linear regression analyses. RESULTS There was a statistically significant correlation between the biomechanical parameters and intraocular pressure, central corneal thickness, axial length, and age. On average, glaucoma patients had the lowest adjusted CH (8.96 ± 1.43 mmHg) and CRF (9.07 ± 1.93 mmHg) values in comparison to OHT patients (CH: 10.2 ± 1.5 mmHg; CRF: 10.6 ± 2.1 mmHg) and controls (CH: 9.7 ± 1.4 mmHg; CRF: 10.2 ± 1.9 mmHg). This difference was statistically significant (CH: p = 0.003; CRF: p = 0.008). There was also a statistically significant difference in adjusted CH (p = 0.001) and CRF (p = 0.004) values between the controls and the visual field groups, with the lowest values being in the most advanced group. CONCLUSIONS Before interpreting corneal biomechanical parameters, it seems important to adjust the measured data for their underlying influencing factors. Glaucoma patients with lower adjusted CH and CRF probably have more advanced disease and should, therefore, be treated more aggressively and monitored more carefully and frequently.
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Affiliation(s)
- Karin R Pillunat
- Department of Ophthalmology, Medical Faculty Carl Gustav Carus, Technische Universität, Fetscherstrasse 74, 01307, Dresden, Germany.
| | - Cosima Hermann
- Department of Ophthalmology, Medical Faculty Carl Gustav Carus, Technische Universität, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Eberhard Spoerl
- Department of Ophthalmology, Medical Faculty Carl Gustav Carus, Technische Universität, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Lutz E Pillunat
- Department of Ophthalmology, Medical Faculty Carl Gustav Carus, Technische Universität, Fetscherstrasse 74, 01307, Dresden, Germany
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11
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Zheng X, Bao F, Geraghty B, Huang J, Yu A, Wang Q. High intercorneal symmetry in corneal biomechanical metrics. EYE AND VISION 2016; 3:7. [PMID: 26949709 PMCID: PMC4779259 DOI: 10.1186/s40662-016-0037-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/20/2016] [Indexed: 12/02/2022]
Abstract
Backgroud To evaluate the symmetry of corneal biomechanical metrics, measured using an ocular response analyzer (ORA) and self-built corneal inflation test platform, in bilateral rabbit corneas and to investigate their relationship with physical intraocular pressure (IOPp). Methods Twenty fresh enucleated eyes from ten rabbits were used for ex vivo whole ocular globe inflation. IOP was increased from 7.5 to 37.5 mmHg with 7.5 mmHg steps and biomechanical metrics were acquired using the ORA. At least 3 examinations were performed at each pressure stage. Two biomechanical metrics, corneal hysteresis (CH) and corneal resistance factor (CRF) were recorded and analyzed as a function of IOPp. Corneal specimens were then excised from the intact ocular globe and tested under inflation conditions up to 45.7 mmHg posterior pressure. The experimental pressure-deformation data was analyzed using an inverse modeling procedure to derive the stress-strain behavior of the cornea. Results A comparison of corneal shape parameters showed no statistically significant difference (P > 0.05) between bilateral eyes. Similarly, there were no statistically significant differences in values of CH, CRF and corneal stiffness (as measured by the tangent modulus, Et) between bilateral eyes (CH: F = 0.94, P = 0.54; CRF: F = 4.42, P = 0.35; Et: F = 3.15, P = 0.12) at different pressure levels. IOPp was highly correlated with CRF while the relationship with CH was less pronounced. Conclusions An obvious interocular symmetry in biomechanical metrics is found in this research. IOP has been shown to have important influences on the value of CRF provided by ORA.
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Affiliation(s)
- XiaoBo Zheng
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325027 China ; The Institution of Ocular Biomechanics, Eye Hospital, Wenzhou Medical University, No. 270# Xueyuan West Road, Wenzhou City, Zhejiang Province 325027 China
| | - FangJun Bao
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325027 China ; The Institution of Ocular Biomechanics, Eye Hospital, Wenzhou Medical University, No. 270# Xueyuan West Road, Wenzhou City, Zhejiang Province 325027 China
| | - Brendan Geraghty
- School of Engineering, University of Liverpool, Liverpool, L69 3GH UK
| | - JinHai Huang
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325027 China ; The Institution of Ocular Biomechanics, Eye Hospital, Wenzhou Medical University, No. 270# Xueyuan West Road, Wenzhou City, Zhejiang Province 325027 China
| | - Ayong Yu
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325027 China ; The Institution of Ocular Biomechanics, Eye Hospital, Wenzhou Medical University, No. 270# Xueyuan West Road, Wenzhou City, Zhejiang Province 325027 China
| | - QinMei Wang
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325027 China ; The Institution of Ocular Biomechanics, Eye Hospital, Wenzhou Medical University, No. 270# Xueyuan West Road, Wenzhou City, Zhejiang Province 325027 China
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Bao F, Deng M, Wang Q, Huang J, Yang J, Whitford C, Geraghty B, Yu A, Elsheikh A. Evaluation of the relationship of corneal biomechanical metrics with physical intraocular pressure and central corneal thickness in ex vivo rabbit eye globes. Exp Eye Res 2015; 137:11-7. [PMID: 26026878 DOI: 10.1016/j.exer.2015.05.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/14/2015] [Accepted: 05/26/2015] [Indexed: 10/23/2022]
Abstract
The relationship of corneal biomechanical metrics provided by the Ocular Response Analyzer (ORA) and Corvis ST (CVS) with physical intraocular pressure (IOPp) and central corneal thickness (CCT) was evaluated. Thirty fresh enucleated eyes of 30 rabbits were used in ex vivo whole globe inflation experiments. IOPp was measured with a pressure transducer and increased from 7.5 to 37.5 mmHg in steps of 7.5 mmHg while biomechanical data was acquired using the ORA and CVS. At least 3 examinations were performed at each pressure level, where CCT and twelve biomechanical metrics were recorded and analyzed as a function of IOPp. The biomechanical metrics included corneal hysteresis (CH) and corneal resistance factor (CRF), obtained by the ORA. They also included the applanation times (A1T, A2T), lengths (A1L, A2L) and velocities (A1V, A2V), in addition to the highest concavity time (HCT), peak distance (PD), radius (HR) and deformation amplitude (DA), obtained by the CVS. The variation of CCT and the twelve biomechanical metrics for the 30 rabbit eyes tested across the 5 pressure stages considered (inter-pressure differences) were statistically significant (P = 0.00). IOPp was highly to moderately correlated with most biomechanical metrics, especially CRF, A1T, A1V, A2V, PD and DA, while the relationships with CH, A2T, A1L and HCT were poor. IOP has important influences on most corneal biomechanical metrics provided by CVS and ORA. Two biomechanical metrics A1V and HR were influenced by CCT after correcting for the effect of IOP in most pressure stages, while the correlation with others were weak. Comparisons of research groups based on ORA and CVS with different IOPs and CCTs may lead to possible misinterpretations if both or one of which are not considered in the analysis.
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Affiliation(s)
- FangJun Bao
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - ManLi Deng
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - QinMei Wang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - JinHai Huang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - Jing Yang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - Charles Whitford
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Brendan Geraghty
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Ayong Yu
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China.
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK; National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK
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Clemmensen K, Hjortdal J. Intraocular pressure and corneal biomechanics in Fuchs' endothelial dystrophy and after posterior lamellar keratoplasty. Acta Ophthalmol 2014; 92:350-4. [PMID: 23607620 DOI: 10.1111/aos.12137] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To evaluate the precision of techniques for measuring intraocular pressure (IOP) in corneas with presumably altered biomechanical properties. METHODS Intraocular pressure was measured with a Goldmann applanation tonometer (GAT), ocular response analyzer (ORA) and dynamic contour tonometer (DCT) in 70 eyes. Thirty-five eyes were normal corneas, 18 eyes had Fuchs' endothelial dystrophy, and 17 eyes had undergone Descemet's stripping automated endothelial keratoplasty (DSAEK) surgery. Corneal hysteresis (CH), corneal resistance factor (CRF) as well as central corneal thickness (CCT) were recorded with the ORA. RESULTS The measured cornea-corrected IOP using ORA was significantly higher than GAT in all three groups (p< 0.001). The DCT differed significantly from the Goldmann only in the Fuchs' group (p= 0.04). The Goldmann and DCT showed no significant between-group differences, whereas IOP measured with the ORA was different between groups (p< 0.001). CH in the DSEAK group differed significantly from the controls (p< 0.001), but there was no significant difference between the DSEAK and Fuchs' groups (p= 0.21). CCT did not differ significantly between the DSAEK and Fuchs' group (p= 0.47). However, both these groups differed significantly from the controls (p< 0.001). CONCLUSION Corneal hysteresis and CRF are reduced in Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. GAT and DCT seem to measure IOP correctly in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. Corneal-corrected IOP as measured with the ORA appears to overestimate IOP in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty.
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Affiliation(s)
- Kåre Clemmensen
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
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Haseltine SJ, Pae J, Ehrlich JR, Shammas M, Radcliffe NM. Variation in corneal hysteresis and central corneal thickness among black, hispanic and white subjects. Acta Ophthalmol 2012; 90:e626-31. [PMID: 22938724 DOI: 10.1111/j.1755-3768.2012.02509.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To determine whether differences in corneal hysteresis (CH) and central corneal thickness (CCT) between black, Hispanic and white subjects exist independently of one another. METHODS Retrospective, cross-sectional data were reviewed for 807 eyes of 410 patients consecutively evaluated for glaucoma. Included patients had open angles, at least one reliable 24-2 perimetric examination and no evidence of nonglaucomatous vision loss. Patients underwent CH measurement with the ocular response analyzer followed by CCT measurement and full ocular examination. Patients were asked to self-classify their race or ethnicity. Statistical analyses were performed to identify characteristics that varied between black, Hispanic and white subjects and to explain this variation. RESULTS Of the 270 patients (511 eyes) included, 84 were black, 96 Hispanic and 90 white. There were no significant differences in diagnosis, sex, age, intraocular pressure or glaucoma severity between races/ethnicities (p ≥ 0.16). Blacks were found to have lower CCT (529.3 μm) and CH (8.7 mmHg) compared to Hispanics (544.7 μm, p = 0.008; 9.4 mmHg, p = 0.007) and whites (549.9 μm, p < 0.001; 9.8 mmHg, p < 0.001). On multivariable analysis, inter-racial/ethnic differences in CCT were not found to exist independent of CH (p ≥ 0.10), whereas the significant intergroup variation in CH remained after adjustment for CCT and other covariates (p ≤ 0.005). CONCLUSIONS Variation in CCT between races/ethnicities does not exist independent of CH. However, significant intergroup variation in CH is present independent of CCT. This finding suggests that CH may be a preferable measurement to evaluate intergroup differences in corneal properties and their relationship to open-angle glaucoma.
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Affiliation(s)
- Sarah J Haseltine
- Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10021, USA
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Freiberg FJ, Lindell J, Thederan LAL, Leippi S, Shen Y, Klink T. Corneal thickness after overnight wear of an intraocular pressure fluctuation contact lens sensor. Acta Ophthalmol 2012; 90:e534-9. [PMID: 22974389 DOI: 10.1111/j.1755-3768.2012.02495.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE To assess the effect of overnight wear of a contact lens-based sensor (CLS) for monitoring of 24-hr intraocular pressure (IOP) fluctuations on central corneal thickness (CCT). MATERIALS AND METHODS Changes in the CCT, mid-peripheral corneal thickness and central corneal radius (CCR) during overnight CLS wear in 20 eligible patients with ocular hypertension or established glaucoma were prospectively studied using ultrasound pachymetry and topography. Corneal thickness and CCR changes were evaluated from pre-to-postsleep, with the fellow eye as control. Paired t-test or Wilcoxon signed-rank test was used as appropriate and with α = 0.05. Relationship between the IOP profile recorded by the CLS and the pre-to-postsleep corneal thickness differences was assessed using the Spearman correlation coefficient. RESULTS After CLS wear, mean CCT had changed from 523 to 537 μm (p = 0.015) in the study eye and from 518 to 522 (p = 0.206) in the fellow eye (n = 15). There was no difference in CCT change between eyes (p = 0.075). There were no statistically significant changes in horizontal or vertical CCR in either eye (p > 0.05 for all). No correlation was found between the pre-to-postsleep differences in the CLS signal and the pre-to-postsleep differences in ultrasound CCT measurements (p = 0.974). CONCLUSION The continuous IOP monitoring does not appear to be affected by differences in corneal thickness that occur during overnight CLS wear, although the CLS did induce some corneal swelling. This effect was not statistically significantly different from the control eye and does not seem to influence the CLS IOP profile.
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Scheler A, Spoerl E, Boehm AG. Effect of diabetes mellitus on corneal biomechanics and measurement of intraocular pressure. Acta Ophthalmol 2012; 90:e447-51. [PMID: 22691299 DOI: 10.1111/j.1755-3768.2012.02437.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To determine whether corneal hysteresis (CH) and corneal resistance factor (CRF) are altered in diabetes and whether these parameters are related to HbA1c. METHODS One randomly chosen eye of 35 healthy subjects and 31 patients with diabetes was examined. Patients with diabetes were divided into group 1 with HbA1c<7% (n=14) and group 2 with HbA1c≥7% (n=17). CH and CRF were measured using ocular response analyzer (ORA); central corneal thickness (CCT) using ultrasound pachymetry; increased intraocular pressure (IOP) using Goldmann tonometer (IOP(GAT) ), Pascal dynamic contour tonometer (IOPpasc), and ORA (IOPcc). As CH and CRF are dependent on IOP and CCT, they were adjusted for IOP and CCT resulting in CHcorr and CRFcorr. RESULTS Mean HbA1c was 5.44±0.46% in healthy subjects, 6.00±0.78% in diabetic group 1, 8.58±2.44% in group 2. CHcorr (p=0.071) and CRFcorr (p=0.067) were not statistically significantly different between healthy subjects and diabetic group 1, but significantly lower in healthy subjects compared to diabetic group 2 [CHcorr (p=0.031), CRFcorr (p=0.029)]. IOPpasc (p=0.012), IOPGAT (p=0.032) and HbA1c (p=0.0001) were statistically significantly different between healthy subjects and all patients with diabetes (groups 1+2), but not age, sex and CCT. Over all patients with diabetes, CHcorr (p=0.012, R2=0.197) and CRFcorr (p=0.008, R2=0.217) were correlated to HbA1c but not in healthy subjects [CHcorr (p=0.931, R2=0.0001), CRFcorr (p=0.837, R2=0.001)]. CONCLUSION In poorly controlled diabetics, CHcorr and CRFcorr are significantly higher compared with those of the healthy subjects and patients with well-controlled diabetes. In diabetes, CHcorr and CRFcorr are correlated to HbA1c, suggesting that the biomechanical properties of the cornea are altered depending on the glucose control.
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Affiliation(s)
- Annabelle Scheler
- Department of Ophthalmology, Elblandklinikum Radebeul, Radebeul, Germany
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Terai N, Raiskup F, Haustein M, Pillunat LE, Spoerl E. Identification of Biomechanical Properties of the Cornea: The Ocular Response Analyzer. Curr Eye Res 2012; 37:553-62. [DOI: 10.3109/02713683.2012.669007] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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