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Salazar-Quiñones L, Fernández-Vigo JI, Pérez-Quiñones Y, Montolío-Marzo E, García-Bella J, Morales-Fernandez L, Sánchez-Del-Hoyo R, García-Feijóo J, Martínez-de-la-Casa JM. Comparison of intraocular pressure measurements between Easyton transpalpebral tonometry and Perkins, iCare iC100 and Corvis ST, and the influence of corneal and anterior scleral thickness. Int Ophthalmol 2023; 43:4121-4129. [PMID: 37632576 DOI: 10.1007/s10792-023-02814-y] [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: 11/15/2022] [Accepted: 07/10/2023] [Indexed: 08/28/2023]
Abstract
PURPOSE To compare intraocular pressure (IOP) measurements between Easyton transpalpebral tonometry and Perkins, iCare iC100 and Corvis ST. Also, to assess the influence of corneal characteristics and anterior scleral thickness (AST) on the IOP measurements. METHODS Sixty-nine eyes from 69 healthy subjects were included. IOP was measured by Easyton, Perkins, iC100 and Corvis ST (corrected IOP, bIOP; and non-corrected IOP, IOPnct). Other variables studied were AST, axial length (AL), and Corvis parameters: Length 1, velocity 1, length 2, velocity 2, peak distance, radius, deformation amplitude, and central corneal thickness (CCT). Pearson correlation, limits of agreement (LoA), and multiple regression analysis were calculated. RESULTS No significant differences in IOP between Easyton and Perkins, iC100, and bIOP were observed (all p > 0.05), being significant only between Perkins and IOPnct ( - 1.49 mmHg, p < 0.001). Bland-Altman graphs showed that the mean difference between Perkins and Easyton was 0.07 mmHg (p < 0.001), and LoA - 7.49 to + 7.39 mmHg. Significant correlations were found between the measurements of Perkins and iC100, IOPnct, bIOP (r = 0.710, 0.628, 0.539; p < 0.001 respectively), iC100 and IOPnct, bIOP (r = 0.627, 0.513; p < 0.001, respectively). The multivariate regression analysis revealed that differences between Perkins and Easyton (adjusted R2 = 0.25) were influenced by AL (B = 1.28, p < 0.008), length 1 (B = 3.13, p < 0.018), and the radius (B = 1.26, p < 0.010). Differences between Perkins and bIOP (adjusted R2 = 0.21) were affected by the CCT (B = 0.029, p < 0.003). CONCLUSIONS There are no significant differences in the IOP measurements between Perkins and Easyton, iC100 or bIOP. Length 1, radius, and CCT have limited influence on these differences, while AST did not show any effect.
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Affiliation(s)
- Liseth Salazar-Quiñones
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain.
| | - José Ignacio Fernández-Vigo
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
| | | | - Elena Montolío-Marzo
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
| | - Javier García-Bella
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
| | - Laura Morales-Fernandez
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
| | - Rafael Sánchez-Del-Hoyo
- Research Methodological Support Unit and Preventive Department, Hospital Clínico San Carlos and "Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC)", Madrid, Spain
| | - Julián García-Feijóo
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
- Institute "Investigaciones Oftalmologicas Ramon Castroviejo", Madrid, Spain
| | - José María Martínez-de-la-Casa
- Department of Ophthalmology, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Universidad Complutense, 28040, Madrid, Spain
- Institute "Investigaciones Oftalmologicas Ramon Castroviejo", Madrid, Spain
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Macedo M, Hatanaka M, Barboza WL, Mingione GM, Ambrósio R, Susanna R. The influence of topical anesthetic and fluorescein on non-contact tonometry measurements using ultra-high-speed dynamic Scheimpflug. Sci Rep 2023; 13:17864. [PMID: 37857798 PMCID: PMC10587345 DOI: 10.1038/s41598-023-45165-5] [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: 07/12/2023] [Accepted: 10/17/2023] [Indexed: 10/21/2023] Open
Abstract
This study aimed to investigate the effects of topical anesthetic and fluorescein drops on intraocular pressure (IOP), central corneal thickness (CCT) and biomechanical properties as measured by Corvis ST (CST-Oculus; Wezlar, Germany) in healthy eyes. A cross-sectional observational study was conducted on 46 healthy patients. The CST measurements were obtained before and immediately after the instillation of topical anesthetic and fluorescein drops. Pre-post instillation data were statistically analyzed. IOP measurements were compared to Goldmann's Applanation Tonometry (GAT), which was also performed after drops instillation. Biomechanical parameters analyzed included applanation 1 velocity, applanation 2 velocity, applanation 1 time, applanation 2 time, whole eye movement, deflection amplitude, and stiffness parameter at first applanation. A statistically significant difference in IOP, both for non-corrected IOP (IOPnct) and biomechanically corrected IOP (bIOP), was observed before and after the instillation of eyedrops. Despite this statistical significance, the observed difference lacked clinical relevance. The IOPnct demonstrated a significant difference pre and post-anesthetic and fluorescein instillation compared to GAT (14.99 ± 2.27 mmHg pre-instillation and 14.62 ± 2.50 mmHg post-instillation, versus 13.98 ± 2.04 mmHg, with p-values of 0.0014 and 0.0490, respectively). Comparable findings were noted when justaposing bIOP to GAT (14.53 ± 2.10 mmHg pre-instillation and 13.15 ± 2.25 mmHg post-instillation, against 13.98 ± 2.04 mmHg, with p-values of 0.0391 and 0.0022, respectively). Additionally, CCT measurements revealed a statistically significant elevation following the administration of topical anesthetic and fluorescein drops (from 544.64 ± 39.85 µm to 586.74 ± 41.71 µm, p < 0.01. None of the analyzed biomechanical parameters showed statistically significant differences after drops instillation. While the administration of topical anesthetic and fluorescein drops induced a statistically significant alteration in both IOPnct and bIOP readings, these changes were not clinically consequential. Furthermore, a notable statistical rise was observed in CCT measurements post-drops instillation, as determined by CST. Yet, corneal biomechanical parameters remained unaffected.
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Affiliation(s)
- Marcelo Macedo
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil.
| | - Marcelo Hatanaka
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil
| | | | | | - Renato Ambrósio
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Remo Susanna
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil
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Elhusseiny AM, Scarcelli G, Saeedi OJ. Corneal Biomechanical Measures for Glaucoma: A Clinical Approach. Bioengineering (Basel) 2023; 10:1108. [PMID: 37892838 PMCID: PMC10604716 DOI: 10.3390/bioengineering10101108] [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: 08/08/2023] [Revised: 09/11/2023] [Accepted: 09/14/2023] [Indexed: 10/29/2023] Open
Abstract
Over the last two decades, there has been growing interest in assessing corneal biomechanics in different diseases, such as keratoconus, glaucoma, and corneal disorders. Given the interaction and structural continuity between the cornea and sclera, evaluating corneal biomechanics may give us further insights into the pathogenesis, diagnosis, progression, and management of glaucoma. Therefore, some authorities have recommended baseline evaluations of corneal biomechanics in all glaucoma and glaucoma suspects patients. Currently, two devices (Ocular Response Analyzer and Corneal Visualization Schiempflug Technology) are commercially available for evaluating corneal biomechanics; however, each device reports different parameters, and there is a weak to moderate agreement between the reported parameters. Studies are further limited by the inclusion of glaucoma subjects taking topical prostaglandin analogues, which may alter corneal biomechanics and contribute to contradicting results, lack of proper stratification of patients, and misinterpretation of the results based on factors that are confounded by intraocular pressure changes. This review aims to summarize the recent evidence on corneal biomechanics in glaucoma patients and insights for future studies to address the current limitations of the literature studying corneal biomechanics.
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Affiliation(s)
- Abdelrahman M. Elhusseiny
- Department of Ophthalmology, Harvey and Bernice Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA;
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Osamah J. Saeedi
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA;
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Hsu FLT, Shih PJ, Wang IJ. Development and validation of an intuitive biomechanics-based method for intraocular pressure measurement: a modal analysis approach. BMC Ophthalmol 2023; 23:124. [PMID: 36973657 PMCID: PMC10041475 DOI: 10.1186/s12886-023-02867-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Current intraocular pressure (IOP) measurements based on non-contact tonometry are derived from statistics-driven equations and lack biomechanical significance, which often leads to under-estimation in post-refractive surgery cornea. This study aims to introduce and validate modal analysis-derived intraocular pressure (mIOP) as a novel method generated through Legendre-based modal decomposition of the anterior corneal contour; it provides an accurate and intuitive IOP measurement from an energy-based perspective. METHODS This retrospective study included 680 patients. Healthy participants were divided into reference (n = 385) and validation (n = 142) datasets, and the others underwent either femtosecond-assisted laser in situ keratomileusis (FS-LASIK, n = 58) or transepithelial photorefractive keratectomy (TPRK, n = 55). Corneal curvature of the right eyes was extracted from raw serial cross-sectional images of the cornea generated by Corvis ST, a noncontact tonometer with a high-speed Scheimpflug-camera. Legendre expansion was then applied to the corneal curvature to obtain the modal profiles (i.e., temporal changes of the coefficient for each basis polynomial [modes]). Using the reference dataset, feature selection on the modal profiles generated a final mIOP model consisting of a single parameter: total area under curve (frames 1-140) divided by the area under curve of the rising phase (frames 24-40) in the fourth mode, i.e. the M4 ratio. Validation was performed in both the healthy validation and postoperative datasets. IOP-Corvis, pachymetry-corrected IOP, biomechanically corrected IOP, and mIOP values were compared. For the FS-LASIK and TPRK groups, pairwise postoperative IOP changes were analyzed through repeated measures analysis of variance, and agreement was examined through Bland-Altman analysis. Using a finite element analysis based three-dimensional model of the human cornea, we further compared the M4 ratio with the true intraocular pressure within the physiological range. RESULTS The M4 ratio-based mIOP demonstrated weak to negligible association with age, radius of corneal curvature, and central corneal thickness (CCT) in all validation analyses, and performed comparably with biomechanically corrected IOP (bIOP) in the refractive surgery groups. Both remained nearly constant postoperatively and were not influenced by CCT changes. Additionally, M4 ratio accurately represented true intraocular pressure in the in silico model. CONCLUSIONS mIOP is a reliable IOP measurement in healthy and postrefractive surgery populations. This energy-based, ratio-derived approach effectively filters out pathological, rotational, misaligned movements and serves as an interpatient self-calibration index. Modal analysis of corneal deformation dynamics provides novel insights into regional corneal responses against pressure loading.
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Affiliation(s)
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, 10048, Taipei, Taiwan.
| | - I-Jong Wang
- College of Medicine, National Taiwan University, 10048, Taipei, Taiwan
- Department of Ophthalmology, National Taiwan University Hospital, 10048, Taipei, Taiwan
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Analysis of Various Modalities for Intraocular Pressure Measurement in Relation to Keratoconus Severity in 246 Eyes of the Homburg Keratoconus Center. Cornea 2023:00003226-990000000-00225. [PMID: 36728050 DOI: 10.1097/ico.0000000000003170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/28/2022] [Indexed: 02/03/2023]
Abstract
PURPOSE Intraocular pressure (IOP) measurement may be difficult in keratoconus (KC) due to corneal protrusion and irregular astigmatism. This study aimed to assess which IOP measurement modality is least affected by KC severity. METHODS Data from 246 corneas of 246 patients with KC were retrospectively analyzed. KC stages were determined using the Topographic KC (TKC) and ABCD KC classifications derived from Pentacam (Oculus, Germany). IOP was measured using Goldmann applanation tonometry (GAT), Ocular Response Analyzer (ORA, Reichert Instruments, USA), and Corvis ST (CST, Oculus, Germany). Cronbach alpha (CA), analysis of variance with Bonferroni correction, Dunnett T3, and Pearson correlation were performed. RESULTS Using CA, the reliability of measurements using various modalities increased to 0.764 to 0.943 when excluding IOP Goldmann overall and in each KC stage (TKC and ABCD). Analysis of variance revealed significant differences between TKC and ABCD stages for almost all IOP modalities. The Bonferroni post hoc test showed significant differences between the measured IOP in earlier and advanced KC stages, except for the biomechanically CST-corrected IOP (bIOP). Pearson correlation analysis showed a significant correlation between IOP and thinnest corneal thickness (TCT) for all IOP modalities except bIOP. CONCLUSIONS CST-based bIOP seems to be best suited for IOP measurement in KC because it did not correlate with TCT in contrast to IOP measurements by ORA or GAT. The measurement results from GAT in patients with KC should be interpreted with care and always in view of corneal thickness. As a thumb rule, we suggest to add at least 2 mm Hg to the measured GAT value.
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Eliasy A, Lopes BT, Wang J, Abass A, Vinciguerra R, Vinciguerra P, Bao FJ, Elsheikh A. Introduction and Clinical Validation of an Updated Biomechanically Corrected Intraocular Pressure bIOP (v2). Curr Eye Res 2022; 48:382-391. [PMID: 36581595 DOI: 10.1080/02713683.2022.2162087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE To improve the stability of the Corvis ST biomechanically-corrected intraocular pressure measurements (bIOP) after refractive surgery and its independence of corneal biomechanics. METHODS A parametric study was carried out using numerical models simulating the behavior of the eye globe under the effects of IOP and Corvis ST external air pressure and used to develop a new algorithm for bIOP; bIOP(v2). It was tested on 528 healthy participants to evaluate correlations with CCT and age. Its ability to compensate for the geometrical changes was tested in 60 LASIK and 80 SMILE patients with six months follow up. The uncorrected Corvis ST IOP (CVS-IOP) and the two versions of biomechanically corrected IOP; bIOP(v1) and bIOP(v2), were compared. RESULTS In the healthy dataset, bIOP(v2) had weak and non-significant correlation with both CCT (R = -0.048, p = .266) and age (R = 0.085, p = .052). For bIOP(v1), the correlation was non-significant with CCT (R = -0.064, p = .139) but significant with age (R = -0.124, p < .05). In both LASIK and SMILE groups, the median change in bIOP(v2) following surgery was below 1 mmHg at follow-up stages and the interquartile range was smaller than both bIOP(v1) and CVS-IOP. CONCLUSION The bIOP(v2) algorithm performs better than bIOP(v1) and CVS-IOP in terms of correlation with CCT and age. The bIOP(v2) also demonstrated the smallest variation after LASIK and SMILE refractive surgeries indicating improved ability to compensate for geometrical changes.
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Affiliation(s)
- Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, UK
| | - Bernardo T Lopes
- School of Engineering, University of Liverpool, Liverpool, UK.,Department of Ophthalmology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Junjie Wang
- Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, UK.,Department of Production Engineering and Mechanical Design, Faculty of Engineering, Port Said University, Egypt
| | - Riccardo Vinciguerra
- School of Engineering, University of Liverpool, Liverpool, UK.,Department of Opthalmology, Humanitas San Pio X Hospital, Milan, Italy
| | - Paolo Vinciguerra
- Department of Biomedical Sciences, Humanitas University, Milan, Italy.,Humanitas Clinical and Research Center, IRCCS, Rozzano, Italy
| | - Fang-Jun Bao
- Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK.,Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK
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Jiménez R, Molina R, Vera J, Redondo B. The short-term effects of wearing swimming goggles on corneal biomechanics. Int Ophthalmol 2022; 42:2773-2784. [PMID: 35378638 PMCID: PMC9420087 DOI: 10.1007/s10792-022-02268-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 03/12/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE This study aimed to assess the impact of wearing swimming goggles (SG) on corneal biomechanics. METHODS Corneal deformation response, central corneal thickness (CCT), intraocular pressure (IOP) and biomechanically corrected intraocular pressure (bIOP) were measured with the Corvis system (Oculus Optikgeräte GmbH, Wetzlar, Germany) in thirty-one healthy young adults while wearing a drilled SG. All measurements were obtained before, at 30 s, 2 min, 3.5 min and 5 min of wearing SG, just after SG removal and after 2 min of SG removal. RESULTS The corneal biomechanics is sensitive to SG wear, observing lower corneal deformability during SG use. Specifically, wearing SG caused an increase in the time and length of the first applanation and radius curvature at the highest concavity, as well as a decrease and in the velocity of the first applanation and time and deformation amplitude of the second applanation (p < 0.001 in all cases). After SG removal, corneal biomechanical parameters showed a rebound-effect, obtaining a higher corneal deformability in comparison with baseline reading (p-corrected < 0.05 in all cases). Additionally, IOP and bIOP significantly increased while wearing SG (p < 0.001 in both cases), whereas CCT remained stable (p = 0.850). CONCLUSIONS Wearing SG modifies the biomechanical properties of the cornea, with reduced corneal deformability during SG wear. The outcomes of this study should be taken into consideration when making clinical decisions in subjects at high risk of developing corneal ectasias or glaucoma, as well as in the post-surgical management of these ocular conditions.
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Affiliation(s)
- Raimundo Jiménez
- CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, University of Granada, Campus de la Fuentenueva 2, 18071, Granada, Spain
| | - Rubén Molina
- CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, University of Granada, Campus de la Fuentenueva 2, 18071, Granada, Spain
| | - Jesús Vera
- CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, University of Granada, Campus de la Fuentenueva 2, 18071, Granada, Spain.
| | - Beatriz Redondo
- CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, University of Granada, Campus de la Fuentenueva 2, 18071, Granada, Spain
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Brazuna R, Salomão M, Esporcatte B, Macedo M, Esporcatte L, Colombini GNUI, Ambrósio R. Corneal biomechanics and glaucoma beyond the bidirectional impact of intraocular pressure and corneal deformation response. REVISTA BRASILEIRA DE OFTALMOLOGIA 2022. [DOI: 10.37039/1982.8551.20220036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
PURPOSE OF THE REVIEW This review summarizes recent findings on corneal hysteresis, a biomechanical property of the cornea. Corneal hysteresis measurements can be easily acquired clinically and may serve as surrogate markers for biomechanical properties of tissues in the back of the eye, like the lamina cribrosa and peripapillary sclera, which may be related to the susceptibility to glaucomatous damage. RECENT FINDINGS Several studies have provided evidence of the associations between corneal hysteresis and clinically relevant outcomes in glaucoma. Corneal hysteresis has been shown to be predictive of glaucoma development in eyes suspected of having the disease. For eyes already diagnosed with glaucoma, lower corneal hysteresis has been associated with higher risk of progression and faster rates of visual field loss over time. Such associations appear to be stronger than those for corneal thickness, suggesting that corneal hysteresis may be a more important predictive factor. Recent evidence has also shown that cornealcorrected intraocular pressure measurements may present advantages compared to conventional Goldmann tonometry in predicting clinically relevant outcomes in glaucoma. SUMMARY Given the evidence supporting corneal hysteresis as an important risk factor for glaucoma development and its progression, practitioners should consider measuring corneal hysteresis in all patients at risk for glaucoma, as well as in those already diagnosed with the disease.
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Affiliation(s)
| | - Felipe A Medeiros
- Duke Eye Center and Department of Ophthalmology
- Department of Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina, USA
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10
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Abstract
PURPOSE OF REVIEW Biomechanics is an important aspect of the complex family of diseases known as the glaucomas. Here, we review recent studies of biomechanics in glaucoma. RECENT FINDINGS Several tissues have direct and/or indirect biomechanical roles in various forms of glaucoma, including the trabecular meshwork, cornea, peripapillary sclera, optic nerve head/sheath, and iris. Multiple mechanosensory mechanisms and signaling pathways continue to be identified in both the trabecular meshwork and optic nerve head. Further, the recent literature describes a variety of approaches for investigating the role of tissue biomechanics as a risk factor for glaucoma, including pathological stiffening of the trabecular meshwork, peripapillary scleral structural changes, and remodeling of the optic nerve head. Finally, there have been advances in incorporating biomechanical information in glaucoma prognoses, including corneal biomechanical parameters and iridial mechanical properties in angle-closure glaucoma. SUMMARY Biomechanics remains an active aspect of glaucoma research, with activity in both basic science and clinical translation. However, the role of biomechanics in glaucoma remains incompletely understood. Therefore, further studies are indicated to identify novel therapeutic approaches that leverage biomechanics. Importantly, clinical translation of appropriate assays of tissue biomechanical properties in glaucoma is also needed.
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Affiliation(s)
- Babak N. Safa
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - Cydney A. Wong
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - Jungmin Ha
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
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Repeatability of Corvis ST to Measure Biomechanical Parameters Before and After Myopic Refractive Surgery. J Cataract Refract Surg 2022; 48:1057-1062. [PMID: 35171143 DOI: 10.1097/j.jcrs.0000000000000909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 02/04/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To assess the repeatability of several corneal biomechanical parameters with a Scheimpflug tonometer (Corvis ST) in myopic eyes and eyes that underwent Transepithelial Photorefractive Keratectomy (TransPRK), Small-Incision Lenticule Extraction (SMILE), or Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) surgery. SETTING Eye Hospital of Wenzhou Medical University, Wenzhou, China. DESIGN Prospective, randomized controlled study. METHODS This study included a total of 315 eyes from 315 patients (135 myopes, 58 post-TransPRK, 52 post-SMILE, and 70 post-FS-LASIK). Three consecutive scans were performed to evaluate the repeatability of the 40 parameters examined. RESULTS In all eyes, the coefficient of variation (CoV) for intraocular pressure (IOP) and biomechanical corrected IOP (bIOP) ranged from 7.29% to 9.47% and 6.11% to 7.75%, respectively; the CoV of pachymetry was <0.8%. The intraclass correlation coefficient (ICC) of Corvis Biomechanical Index-Laser Vision Correction (CBI-LVC) was 0.680 for post-TransPRK, 0.978 for post-SMILE, and 0.911 for post-FS-LASIK. The CoV of Stress-Strain Index (SSI) was 204.93% for post-TransPRK, 91.92% for post-SMILE, and 171.72% for post-FS-LASIK. The CoV of the six clinically important dynamic corneal response (DCR) parameters ranged from 2.0% to 7.8% for myopia, 1.8% to 11.1% for post-TransPRK, 2.1% to 8.7% for post-SMILE, and 1.8% to 8.8% for post-FS-LASIK. CONCLUSIONS Excellent intra-measurement repeatability of IOP, bIOP and pachymetry was observed in all groups; SSI measurement in post-laser vision correction (LVC) corneas displayed more variation. Caution is warranted when assessing SSI in post-LVC corneas for the purpose of diagnosing iatrogenic ectasia or evaluating biomechanical remodeling of postoperative refractive corneas.
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Silva N, Ferreira A, Baptista PM, Figueiredo A, Reis R, Sampaio I, Beirão J, Vinciguerra R, Menéres P, Menéres MJ. Corneal Biomechanics for Ocular Hypertension, Primary Open-Angle Glaucoma, and Amyloidotic Glaucoma: A Comparative Study by Corvis ST. Clin Ophthalmol 2022; 16:71-83. [PMID: 35035215 PMCID: PMC8754459 DOI: 10.2147/opth.s350029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 12/21/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND To evaluate biomechanical parameters of the cornea provided by Corvis ST in patients with ocular hypertension, primary open-angle glaucoma, and amyloidotic glaucoma and to compare with healthy controls. METHODS This was a cross-sectional study of patients with ocular hypertension, primary open-angle glaucoma, and amyloidotic glaucoma that underwent Corvis ST imaging. Primary outcome was the comparison of corneal biomechanical parameters between study groups after adjusting for age, gender, Goldmann intraocular pressure (GAT-IOP), and prostaglandin analogues medication. Secondary outcome was the comparison of different IOP measurements in each group. RESULTS One hundred and eighty-three eyes from 115 patients were included: 61 with primary open-angle glaucoma, 32 with amyloidotic glaucoma, 37 with ocular hypertension and 53 were healthy controls. Amyloidotic glaucoma group had smaller radius (p=0.025), lower deflection amplitude at highest concavity (p=0.019), and higher integrated radius (p=0.014) than controls. Ocular hypertension group had higher stiffness parameter at first applanation (p=0.043) than those with primary open-angle glaucoma, and higher stress-strain index (p=0.049) than those with amyloidotic glaucoma. Biomechanically corrected intraocular pressure was significantly lower than Goldmann intraocular pressure in group with primary open-angle glaucoma (p=0.005) and control group (p=0.013), and Goldmann intraocular pressure adjusted for pachymetry in group with primary open-angle glaucoma (p=0.01). CONCLUSION Eyes with amyloidotic glaucoma have more deformable corneas, while eyes with ocular hypertension have less deformable corneas. These findings may be linked to the susceptibility to glaucomatous damage and progression. There were significant differences between Goldmann applanation tonometry and biomechanically corrected intraocular ocular pressure provided by Corvis ST.
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Affiliation(s)
- Nisa Silva
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
| | - André Ferreira
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
- Unit of Anatomy, Department of Biomedicine, Faculty of Medicine of University of Porto, Porto, 4200-319, Portugal
| | - Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
| | - Ana Figueiredo
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
| | - Rita Reis
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
| | - Isabel Sampaio
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
| | - João Beirão
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
- Department of Ophthalmology, Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto, 4050-313, Portugal
| | - Riccardo Vinciguerra
- Ophthalmology Department, Humanitas San Pio X Hospital, Milan, Italy
- The School of Engineering, University of Liverpool, Liverpool, UK
| | - Pedro Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
- Department of Ophthalmology, Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto, 4050-313, Portugal
| | - Maria João Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, 4099-001, Portugal
- Department of Ophthalmology, Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto, 4050-313, Portugal
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13
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Association of Corneal Biomechanics Properties with Myopia in a Child and a Parent Cohort: Hong Kong Children Eye Study. Diagnostics (Basel) 2021; 11:diagnostics11122357. [PMID: 34943594 PMCID: PMC8700309 DOI: 10.3390/diagnostics11122357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 11/29/2021] [Accepted: 12/07/2021] [Indexed: 11/17/2022] Open
Abstract
Associations between corneal biomechanics, axial elongation and myopia are important but previous results are conflicting. Our population-based study aimed to investigate factors associated with corneal biomechanics, and their relationships with myopia in children and adults. Data from 3643 children and 1994 parents showed that children had smaller deformation amplitudes (DA) than parents (p < 0.001). A larger DA was significantly associated with elongated axial length (AL; children: ß = 0.011; adults: ß = 0.0013), higher corneal curvature (children: ß = 0.0086; adults: ß = 0.0096), older age (children: ß = 0.010; adults: ß = 0.0013), and lower intraocular pressure (IOP; children: ß = −0.029; adults: ß = −0.031) in both cohorts. The coefficient of age for DA in children was larger than in adults (p < 0.001), indicating that the DA change with age in children is faster than in adults. DA was significantly associated with spherical equivalent (p < 0.001) resulting from its correlation with AL and corneal curvature. In conclusion, the cornea is more deformable in adults than in children, whereas corneal deformation amplitude increases faster with age in children than that in adults, along with AL elongation. Longer AL, steeper corneal curvature, older age and smaller IOP correspond to a more deformable cornea. The association between corneal deformation amplitude and refraction was mediated via AL and corneal curvature.
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Wang X, McAlinden C, Zhang H, Yan J, Wang D, Wei W, Mi S. Assessment of corneal biomechanics, tonometry and pachymetry with the Corvis ST in myopia. Sci Rep 2021; 11:3041. [PMID: 33542296 PMCID: PMC7862660 DOI: 10.1038/s41598-020-80915-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
To evaluate the repeatability of Corvis ST corneal biomechanical, tonometry and pachymetry measurements, and agreement of pachymetry measures with the Pentacam HR and RTVue OCT. Three consecutive measurements of the right eye of 238 myopic subjects were acquired with the Corvis ST, Pentacam HR, and RTVue OCT. Repeatability of Corvis ST was evaluated by within-subject standard deviation [Sw] and repeatability limit [r]. The agreement of central corneal thickness (CCT) measurements were compared among the three instruments using the Bland-Altman limits of agreement. Comparisons were further stratified by CCT (Corneathin ≤ 500 µm; Corneanormal = 500-550 µm; Corneathick > 550 µm). Sw was below 1 mmHg in Corneathin, Corneanormal, and Corneathick groups for IOP and bIOP. Sw for SP-A1 were 4.880, 6.128, 7.719 mmHg/mm respectively. Sw for CBI were 0.228, 0.157, 0.076, and correspondingly Sw for TBI and SSI were 0.094 and 0.056, 0.079 and 0.053, 0.070 and 0.053. The Bland-Altman plots for CCT implied poor agreement with mean differences of 29.49 µm between Corvis and OCT, 9.33 µm between Pentacam and OCT, and 20.16 µm between Corvis and Pentacam. The Corvis ST showed good repeatability with the exception of CBI in the various CCT groups. The CCT measured by Corvis ST was not interchangeable with Pentacam HR and RTVue OCT.
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Affiliation(s)
- Xiaorui Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.,Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Colm McAlinden
- Department of Ophthalmology, Singleton Hospital, Swansea Bay University Health Board, Swansea, UK
| | - Hongbing Zhang
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Jie Yan
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Dan Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Wei Wei
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China. .,Shaanxi Institute of Ophthalmology, Xi'an, China.
| | - Shengjian Mi
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.
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15
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Liu G, Rong H, Pei R, Du B, Jin N, Wang D, Jin C, Wei R. Age distribution and associated factors of cornea biomechanical parameter stress-strain index in Chinese healthy population. BMC Ophthalmol 2020; 20:436. [PMID: 33143686 PMCID: PMC7607623 DOI: 10.1186/s12886-020-01704-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Abstract
Background To investigate the new cornea biomechanical parameter stress-strain index (SSI) in Chinese healthy people and the factors associated with SSI. Methods A total of 175 eyes from 175 participants were included in this study. Axial length was measured with the Lenstar LS-900. Pentacam measured curvature of the cornea and anterior chamber volume (ACV). Cornea biomechanical properties assessments were performed by corneal visualization Scheimpflug technology (Corvis ST). Student’s t-test, one-way ANOVA, partial least square linear regression (PLSLR) and linear mixed effects (LME) model were used in the statistical analysis. Results The mean (±SD) SSI was 1.14 ± 0.22 (range, 0.66–1.78) in all subjects and affected by age significantly after age of 35 (P < 0.05). In LME models, SSI was significantly associated with age (β = 0.526, P < 0.001), axial length (AL) (β = − 0.541, P < 0.001), intraocular pressure (IOP) (β = 0.326, P < 0.001) and steepest radius of anterior corneal curvature (RsF) (β = 0.229, P < 0.001) but not with ACV, biomechanical corrected intraocular pressure (bIOP), flattest radius of anterior corneal curvature (RfF) or central corneal thickness (CCT) (P > 0.05 for each). Conclusions SSI increased with age after the age of 35. In addition to age, SSI was positively correlated with RsF and IOP, while negatively correlated with AL.
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Affiliation(s)
- Guihua Liu
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Hua Rong
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Ruxia Pei
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Bei Du
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Nan Jin
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Di Wang
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Chengcheng Jin
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China
| | - Ruihua Wei
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Postal address: 251 Fukang Road, Nankai District, Tianjin, China. .,Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Postal address: 251 Fukang Road, Nankai District, Tianjin, China.
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16
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Hohberger B, Sommerfeld C, Lucio M, Bergua A. ICare Pro: Age Dependent Effect of Central Corneal Thickness on Intraocular Pressure in Glaucoma and Ocular Hypertension Patients. Curr Eye Res 2020; 45:668-674. [PMID: 31905299 DOI: 10.1080/02713683.2019.1696977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: Measurement of the exact intraocular pressure (IOP) is essential in glaucoma diagnosis and follow-up, thus all therapeutic options affect IOP in order to win sighted lifetime. As it is known that corneal properties of glaucoma patients differ from normal subjects, the present study aimed to investigate the influence of CCT on rebound tonometry (ICT, ICare Pro) in glaucoma and ocular hypertension patients in dependency of age additionally considering different times of day.Methods: Three hundred sixty-two eyes of 190 subjects were included: 339 open-angle glaucoma and 23 ocular hypertension. IOP was measured at 5 different times of day (6 a.m., 12 a.m., 4 p.m., 9 p.m., and 0 p.m.) by Goldmann applanation tonometry (GAT) and Icare Pro rebound tonometry in a sitting position. Central corneal thickness was measured by central ultrasonic pachymetry (Pachymeter SP-100). Δ ICT was calculated as the difference of GAT, corrected according to age and CCT, and ICT, respectively at each time point.Results: All different GAT time points data correlated significantly (p < .05) with ICT time points. An age effect was observed on overall ICT (p = .02). A decrease of ICT was observed with increasing age. The within differences among ICT repeated measurements were significant as well. Additionally, repeated means of Δ ICT correlated significantly with age and CCT. Intercepts and coefficients were offered for each time point, respectively. GLM model yielded a relation between MD (dependent variable) and age together with CCT (age: p < .0001) and (CCT: p = .043).Conclusions: IOP measurements with ICare Pro were shown to be dependent on age, CCT and time of day in glaucoma and ocular hypertension patients. Thus, aging, corneal biomechanical properties and circadian rhythms should be taken into consideration when adjusting IOP.
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Affiliation(s)
- Bettina Hohberger
- Department of Ophthalmology, University of Erlangen, Friedrich Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Carlos Sommerfeld
- Department of Ophthalmology, University of Erlangen, Friedrich Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Marianna Lucio
- Helmholtz Zentrum München - German Research Center for Environmental Health, Research Unit Analytical BioGeoChemistry, Neuherberg, Germany
| | - Antonio Bergua
- Department of Ophthalmology, University of Erlangen, Friedrich Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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