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Wan K, Wolffsohn JS, Cho P. Role of waveform signal parameters in the classification of children as relatively slow and fast myopia progressors. Clin Exp Optom 2024; 107:402-408. [PMID: 36797056 DOI: 10.1080/08164622.2023.2177098] [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: 11/17/2022] [Revised: 01/14/2023] [Accepted: 02/01/2023] [Indexed: 02/18/2023] Open
Abstract
CLINICAL RELEVANCE Identification of the baseline chracteristics for children undergoing orthokeratology with relatively fast myopia progression can allow a more accurate determination of the risk/benefit ratio. BACKGROUND This study aimed to investigate if baseline corneal biomechanics can classify relatively slow and fast myopia progression in children. METHODS Children aged six to 12 years with low myopia (0.50 to 4.00 D) and astigmatism (less than or equal to 1.25 D), were recruited. Participants were randomised to be fitted with orthokeratology contact lenses with a conventional compression factor (0.75 D, n = 29) or an increased compression factor (1.75 D, n = 33). Relatively fast progressors were defined as participants who had axial elongation of 0.34 mm or above per 2 years. A binomial logistic regression analysis and a classification and regression tree model were used in the data analysis. The corneal biomechanics were measured with a bidirectional applanation device. The axial length was measured by a masked examiner. RESULTS As there were no significant between-group differences in the baseline data (all p > 0.05), data were combined for analysis. The mean ± SD axial elongation for relatively slow (n = 27) and fast (n = 35) progressors were 0.18 ± 0.14 mm and 0.64 ± 0.23 mm per 2 years, respectively. The area under the curve (p2area1) was significantly higher in relatively fast progressors (p = 0.018). The binomial logistic regression and classification and regression tree model analysis showed that baseline age and p2area1 could differentiate between slow and fast progressors over 2 years. CONCLUSIONS Corneal biomechanics could be a potential predictor of axial elongation in orthokeratology contact lens-wearing children.
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Affiliation(s)
- Kin Wan
- School of Optometry, The Hong Kong Polytechnic University, HKSAR, Hong Kong, China
| | | | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, HKSAR, Hong Kong, China
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Yii F, Strang N, Bernabeu MO, Dhillon B, MacGillivray T. Corneal biomechanics are not exclusively compromised in high myopia. Ophthalmic Physiol Opt 2024. [PMID: 38563586 DOI: 10.1111/opo.13313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/15/2024] [Accepted: 03/22/2024] [Indexed: 04/04/2024]
Abstract
INTRODUCTION Research assuming linearity has concluded that corneal biomechanics are compromised in high myopia. We investigated whether this assumption was appropriate and re-examined these associations across different levels of myopia. METHODS Myopic (spherical equivalent refraction, SER ≤ -0.50 D) eyes of 10,488 adults aged 40-69 years without any history of systemic and ocular conditions were identified in the UK Biobank. Ordinary least squares (OLS) regression was employed to test the linear association between corneal hysteresis (CH) or corneal resistance factor (CRF), separately, and SER while controlling for age, sex, corneal radius and intraocular pressure. Quantile regression (QR) was used to test the same set of associations across 49 equally spaced conditional quantiles of SER. RESULTS In OLS regression, each standard deviation (SD) decrease in CH and CRF was associated with 0.08 D (95% CI: 0.04-0.12; p < 0.001) and 0.10 D (95% CI: 0.04-0.15; p < 0.001) higher myopia, respectively. However, residual analysis indicated that the linearity assumption was violated. QR revealed no evidence of a significant association between CH/CRF and SER in low myopia, but a significant (p < 0.05) positive association became evident from -2.78 D (0.06 and 0.08 D higher myopia per SD decrease in CH and CRF). The magnitude of association increased exponentially with increasing myopia: in the -5.03 D quantile, every SD decrease in CH and CRF was associated with 0.17 D (95% CI: 0.08-0.25; p < 0.001) and 0.21 D (95% CI: 0.10-0.31; p < 0.001) higher myopia. In the -8.63 D quantile, this further increased to 0.54 D (95% CI: 0.33-0.76; p < 0.001) and 0.67 D (95% CI: 0.41-0.93; p < 0.001) higher myopia per SD decrease in CH and CRF. CONCLUSIONS Corneal biomechanics appeared compromised from around -3.00 D. These changes were observed to be exponential with increasing myopia.
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Affiliation(s)
- Fabian Yii
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK
| | - Niall Strang
- Department of Vision Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Miguel O Bernabeu
- Centre for Medical Informatics, Usher Institute, The University of Edinburgh, Edinburgh, UK
- The Bayes Centre, The University of Edinburgh, Edinburgh, UK
| | - Baljean Dhillon
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK
- Princess Alexandra Eye Pavilion, NHS Lothian, Edinburgh, UK
| | - Tom MacGillivray
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK
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Kenia VP, Kenia RV, Bendre P, Pirdankar OH. Corneal stress-strain index in myopic Indian population. Oman J Ophthalmol 2024; 17:47-52. [PMID: 38524314 PMCID: PMC10957058 DOI: 10.4103/ojo.ojo_122_23] [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: 06/09/2023] [Accepted: 11/18/2023] [Indexed: 03/26/2024] Open
Abstract
AIM The purpose is to study the corneal stress-strain index (SSI) in myopic refractive error among Indian subjects. METHODS A retrospective study where young myopic subjects aged between 11 and 35 years who had undergone corneal biomechanics assessment using Corvis ST between January 2017 and December 2021 were enrolled. Subjects with central corneal thickness (CCT) <500 μ, intraocular pressure (IOP) >21 mmHg, history of any systemic and ocular disease or any previous ocular surgery, high astigmatism, corneal disease such as keratoconus were excluded. Subjects with missing data or having poor quality scan were excluded. Corneal biomechanical properties and corneal SSI were assessed using Corvis ST. For statistical purposes, eyes were divided into four different groups and were analyzed using one-way ANOVA. RESULTS Nine hundred and sixty-six myopic eyes with mean ± standard deviation age, IOP, and CCT of 26.89 ± 4.92 years, 16.94 ± 2.00 mmHg, and 540.18 ± 25.23 microns, respectively, were included. There were 311, 388, 172, and 95 eyes that were low, moderate, severe, and extreme myopic. Deformation amplitude ratio at 1 mm and 2 mm were similar across different myopic groups. A significant increase in max inverse radius, ambrosia relational thickness, biomechanically corrected IOP, integrated radius was noted with an increase in myopic refractive error. Corvis biomechanical index, corneal SSI was found to be decreased significantly with an increase in myopic refractive error. We noted a significant positive association between myopic refractive error and SSI (P < 0.001). CONCLUSION Corneal SSI was found to be reduced in extreme myopic eyes.
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Affiliation(s)
- Vaishal P. Kenia
- Department of Cataract and Refractive Surgery, Kenia Eye Hospital, Mumbai, Maharashtra, India
| | - Raj V. Kenia
- Department of Ophthalmology, Kenia Foundation, Mumbai, Maharashtra, India
| | - Pradnya Bendre
- Department of Cataract and Refractive Surgery, Kenia Eye Hospital, Mumbai, Maharashtra, India
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Wu W, Song Y, Sun M, Li Y, Xu Y, Xu M, Yang Y, Li S, Zhang F. Corneal metabolic biomarkers for moderate and high myopia in human. Exp Eye Res 2023; 237:109689. [PMID: 37871883 DOI: 10.1016/j.exer.2023.109689] [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: 04/11/2023] [Revised: 10/13/2023] [Accepted: 10/20/2023] [Indexed: 10/25/2023]
Abstract
This study aimed to identify the corneal metabolic biomarkers for moderate and high myopia in human. We enrolled 221 eyes from 221 subjects with myopia to perform the femtosecond laser small incision lenticule extraction (SMILE) surgery. Among these, 71 eyes of 71 subjects were enrolled in the low myopic group, 75 eyes of 75 subjects in the moderate myopic group and 75 eyes of 75 subjects in the high myopic group. The untargeted metabolomics analysis was performed to analyze the corneal tissues extracted during the SMILE surgery using an ultra-high-performance liquid chromatography (UHPLC) coupled to a quadrupole time-of-flight (Q-TOF) mass spectrometry (MS). The one-way analysis of variance (ANOVA) was used to identify the different metabolites among the three myopic groups, the orthogonal partial least-squares discriminant analysis (OPLS-DA) model was used to reveal the different metabolites between moderate myopia and low myopia, and between high myopia and low myopia. The Venn gram was used to find the overlapped metabolites of the three datasets of the different metabolites. The stepwise multiple linear regression analysis was used to determine the metabolic molecules associated with manifest refractive spherical equivalents (MRSE). The Receiver Operating Characteristics (ROC) analysis was performed to reveal the corneal biomarkers for moderate and high myopia. The hub biomarker was further selected by the networks among different metabolites created by the Cytoscape software. A total of 1594 metabolites were identified in myopic corneas. 321 metabolites were different among the three myopic groups, 106 metabolites were different between high myopic corneas and low myopic corneas, 104 metabolites were different between moderate myopic corneas and low myopic corneas, and 30 metabolic molecules overlapped among the three datasets. The multivariate linear regression analysis revealed the myopic degree was significantly influenced by the corneal levels of azelaic acid, arginine-proline (Arg-Pro), 1-stearoyl-2-myristoyl-sn-glycero-3-phosphocholine, and hypoxanthine. The ROC curve analysis showed that azelaic acid, Arg-Pro and hypoxanthine were effective in discriminating low myopia from moderate to high myopia with the area under the curve (AUC) values as 0.982, 0.991 and 0.982 for azelaic acid, Arg-Pro and hypoxanthine respectively. The network analysis suggested that Arg-Pro had the maximum connections among these three biomarkers. Thus, this study identified azelaic acid, Arg-Pro and hypoxanthine as corneal biomarkers to discriminate low myopia from moderate to high myopia, with Arg-Pro serving as the hub biomarker for moderate and high myopia.
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Affiliation(s)
- Wenjing Wu
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Yanzheng Song
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Mingshen Sun
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Yu Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Yushan Xu
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Mengyao Xu
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Yuxin Yang
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Shiming Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China
| | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, No. 1, Dongjiaomin Lane, Dongcheng District, Beijing, 100730, China.
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Biswas S, Biswas P. Relationship between Diurnal Variation in Intraocular Pressure and Central Corneal Power. Optom Vis Sci 2023; 100:96-104. [PMID: 36705719 DOI: 10.1097/opx.0000000000001974] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
SIGNIFICANCE Relationship between intraocular pressure (IOP) change and central corneal curvature is complicated by measurement techniques and corneal biomechanical parameters. Findings from this study indicate that it is worthwhile to observe the association between diurnal change in IOP and corneal power. PURPOSE This study aimed to investigate the relationship between the diurnal change in IOP and central corneal power among eyes with and without myopia. METHODS Sixty healthy eyes of 24 emmetropes and 36 myopes were recruited for this cross-sectional study. Both anterior and posterior central corneal powers of the steep (Ks), flat (Kf), mean meridian (Km), best-fit spheres, and central corneal thickness were recorded followed by the IOP (Goldmann-correlated IOP [IOPg] and corneal-compensated IOP) and corneal biomechanics (corneal hysteresis and corneal resistance factor). Measurements were obtained every 3 hours from 9.30 am to 6.30 pm . Linear-mixed model was used to determine the relationship between the change in IOP and the associated change in corneal measurements (adjusted for age, sex, refractive error, central corneal thickness, and biomechanics) among the myopic and nonmyopic eyes. RESULTS Group mean, amplitude of change, and the diurnal change in IOPg were (mean ± standard deviation) 15.14 ± 2.50, 3.33 ± 1.44, and 1.81 ± 1.25 mmHg, respectively. Overall, an IOP increase was associated with a decrease in the adjusted anterior corneal powers. Myopic eyes were associated with a decrease of 0.04 D (95% confidence interval [CI], 0.07 to 0.01 D; P = .02) in Ks and 0.03 D (95% CI, 0.06 to 0.001 D; P = .047) in Kf per mmHg increase in IOP, whereas for emmetropes, per mmHg increase in IOP only flattened the Kf by 0.03 D (95% CI, 0.06 to 0.004 D; P = .02). CONCLUSIONS Change in anterior corneal power was inversely related to the change in IOPg, with myopic and nonmyopic eyes reporting a significant but differential impact of IOP. Clinicians must keep in mind the impact of large IOP fluctuation on the anterior corneal power.
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Pérez-López M, Ting DSJ, Lanzagorta-Aresti A, Montolio-Marzo S, Davó-Cabrera J, Cid-García I. Influence of corneal biomechanical properties on intraocular pressure measurement in different types of Graves’ orbitopathy. Eur J Ophthalmol 2023; 33:567-573. [PMID: 36062595 DOI: 10.1177/11206721221124655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND/AIMS To compare the ocular biomechanical properties of inactive Grave's orbitopathy (GO) patients and healthy subjects and to evaluate the influence of severity and phenotype of GO on these parameters. METHODS This was a cross-sectional study. All included inactive GO patients and healthy controls underwent complete ocular examination, including Goldman applanation tonometry (GAT), corneal biomechanical analysis using Ocular Response Analyser (ORA), and corneal epithelial thickness analysis using Optovue. Patients with inactive GO were classified based on the severity and orbital phenotype (predominantly myogenic or lipogenic). Comparison among groups was performed. RESULTS 60 eyes from 30 inactive GO patients and 30 healthy eyes were examined. Corneal hysteresis (CH) was significantly lower in inactive GO patients (9.6 [p25 8.1; p75 11.2]) compared to controls (10.4 [9.8; 11.5]) (p = 0.012). In GO patients, cornea compensated intraocular pressure (IOPcc) was significantly higher than Goldman applanation tonometry IOP (IOP-GAT) (p = 0.001). A total of 13.3% GO patients were initially classified as having ocular hypertension (OHT; defined as IOP > 21 mmHg with no signs of glaucomatous optic neuropathy) based on IOP-GAT measurement. According to IOPcc, 27.8% of GO patients were classified as OHT. In GO patients, no differences were found in corneal bimechanical properties according to the disease severity or orbital phenotype. CONCLUSIONS CH is significantly lower in inactive GO patients compared to healthy subjects. ORA corrected IOP was significantly higher in GO patients compared to IOP-GAT. No differences in corneal biomechanical properties between mild and moderate-to-severe GO disease and between myogenic and lipogenic orbitopathy were found.
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Affiliation(s)
- Marta Pérez-López
- Ophthalmology Department, 16273Hospital Universitario y Politécnico La Fe, Valencia, Spain
| | - Darren S J Ting
- Academic Ophthalmology, School of Medicine, 6123University of Nottingham, Nottingham, UK.,Department of Ophthalmology, Queen's Medical Centre, Nottingham, UK
| | | | | | - Juan Davó-Cabrera
- Ophthalmology Department, 16273Hospital Universitario y Politécnico La Fe, Valencia, Spain
| | - Isabel Cid-García
- Ophthalmology Department, 150239Fisabio Oftalmología Médica, Valencia, Spain
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Marinescu M, Dascalescu D, Constantin M, Coviltir V, Burcel M, Darabus D, Ciuluvica R, Stanila D, Potop V, Alexandrescu C. Corneal Biomechanics - an Emerging Ocular Property with a Significant Impact. MAEDICA 2022; 17:925-930. [PMID: 36818253 PMCID: PMC9923086 DOI: 10.26574/maedica.2022.17.4.925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Corneal biomechanical properties reflect the capacity of the cornea to respond to applied mechanical forces. They are an increasingly important domain in ocular pathology, correlated to the diagnosis and evolution of eye diseases such as refractive errors, glaucoma or corneal ectasias. Refractive errors constitute a significant etiology of decreased vision worldwide, with a particular impact in children. Myopic eyes significantly differ from emmetropic eyes in terms of morphology and biomechanics, with differences being reported in both adults and children. In the latter, corneal hysteresis (CH) and the corneal resistance factor (CRF) are significantly lower in myopic individuals, and both biomechanical parameters correlate with the central corneal thickness and axial length. Glaucoma is a progressive optic neuropathy that leads to thinning of the nerve fiber layer and specific visual field loss, in which intraocular pressure (IOP) is an important risk factor. There is an inverse correlation between IOP and CH - a low hysteresis is associated with a high IOP. Furthermore, CH is on average lower in primary open angle glaucoma (POAG) compared to ocular hypertension (OHT) for the same IOP. Significant correlations between CH and the thickness of the ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL), in both POAG and OHT, have been described. Keratoconus is the most frequent corneal ectasia, which leads to a progressive thinning and protruding of the cornea. Biomechanical parameters are severely affected in keratoconus - usually, both CH and CRF are lower compared to normal eyes. The biomechanical behavior of the cornea modulates the evolution of several ocular pathologies. As research is ongoing, more data will enable us to apply this knowledge in diagnosing disease more efficiently and targeting the right treatment for the right patient, including refractive surgery.
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Affiliation(s)
- Maria Marinescu
- Department of Ophthalmology, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
- Department of Ophthalmology, Clinical Hospital for Ophthalmological Emergencies Bucharest, Romania
| | - Dana Dascalescu
- Department of Ophthalmology, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
- Department of Ophthalmology, Clinical Hospital for Ophthalmological Emergencies Bucharest, Romania
| | | | - Valeria Coviltir
- Department of Ophthalmology, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
- Department of Ophthalmology, Clinical Hospital for Ophthalmological Emergencies Bucharest, Romania
| | - Miruna Burcel
- Department of Ophthalmology, Oftaclinic Bucharest, Romania
| | - Diana Darabus
- Department of Ophthalmology, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania
| | - Radu Ciuluvica
- Department of Anatomy, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Dan Stanila
- Department of Ophthalmology, Faculty of Medicine, "Lucian Blaga" University, Sibiu, Romania
| | - Vasile Potop
- Department of Ophthalmology, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
- Department of Ophthalmology, Clinical Hospital for Ophthalmological Emergencies Bucharest, Romania
| | - Cristina Alexandrescu
- Department of Ophthalmology, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
- Department of Ophthalmology, Bucharest Emergency University Hospital, Romania
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Wang P, Song Y, Lin F, Wang Z, Gao X, Cheng W, Chen M, Peng Y, Liu Y, Zhang X, Chen S. Comparison of Non-contact Tonometry and Goldmann Applanation Tonometry Measurements in Non-pathologic High Myopia. Front Med (Lausanne) 2022; 9:819715. [PMID: 35308502 PMCID: PMC8927768 DOI: 10.3389/fmed.2022.819715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
PurposeTo compare intraocular pressure (IOP) values obtained using Goldmann applanation tonometry (IOPGAT) and non-contact tonometry (IOPNCT) in a non-pathologic high myopia population.MethodsA total of 720 eyes from 720 Chinese adults with non-pathologic high myopia were enrolled in this cross-sectional study. Demographic and ocular characteristics, including axial length, refractive error, central corneal thickness (CCT), and corneal curvature (CC) were recorded. Each patient was successively treated with IOPNCT and IOPGAT. Univariate and multivariable linear regression analyses were conducted to detect factors associated with IOPNCT and IOPGAT, as well as the measurement difference between the two devices (IOPNCT−GAT).ResultsIn this non-pathologic high myopia population, the mean IOPNCT and IOPGAT values were 17.60 ± 2.76 mmHg and 13.85 ± 2.43 mmHg, respectively. The IOP measurements of the two devices were significantly correlated (r = 0.681, P < 0.001), however, IOPNCT overestimated IOPGAT with a mean difference of 3.75 mmHg (95% confidence interval: 3.60–3.91 mmHg). In multivariate regression, IOPNCT was significantly associated with body mass index (standardized β = 0.075, p = 0.033), systolic blood pressure (SBP) (standardized β = 0.170, p < 0.001), and CCT (standardized β = 0.526, p < 0.001). As for IOPGAT, only SBP (standardized β = 0.162, p < 0.001), CCT (standardized β = 0.259, p < 0.001), and CC (standardized β = 0.156, p < 0.001) were significantly correlated. The mean IOPNCT−GAT difference increased with younger age (standardized β = −0.134, p < 0.001), higher body mass index (standardized β = 0.091, p = 0.009), higher SBP (standardized β = 0.074, p = 0.027), thicker CCT (standardized β = 0.506, p < 0.001), and lower IOPGAT (standardized β = −0.409, p < 0.001).ConclusionIn the non-pathologic high myopia population, IOPNCT overestimated IOPGAT at 3.75 ± 2.10 mmHg. This study suggests that the difference between the values obtained by the two devices, and their respective influencing factors, should be considered in the clinical evaluation and management of highly myopic populations.
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Xin Y, Kang BS, Zheng YP, Shan SW, Kee CS, Tan Y. Biophysical properties of corneal cells reflect high myopia progression. Biophys J 2021; 120:3498-3507. [PMID: 34022236 DOI: 10.1016/j.bpj.2021.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/07/2021] [Accepted: 05/17/2021] [Indexed: 01/07/2023] Open
Abstract
Myopia is a common ocular disorder with significant alterations in the anterior ocular structure, including the cornea. The cell biophysical phenotype has been proposed to reflect the state of various diseases. However, the biophysical properties of corneal cells have not been characterized during myopia progression and their relationship with myopia remains unknown. This study characterizes the biophysical properties of corneal cells in normal, myopic, and recovered conditions, using two classical myopia models. Surprisingly, myopic corneal cells considerably reduce F-actin and microtubule content and cellular stiffness and generate elevated traction force compared with control cells. When myopia is restored to the healthy state, these biophysical properties are partially or fully restored to the levels of control cells. Furthermore, the level of chromatin condensation is significantly increased in the nucleus of myopic corneal cells and reduced to a level similar to healthy cells after recovery. These findings demonstrate that the reversible biophysical alterations of corneal cells reflect myopia progression, facilitating the study of the role of corneal cell biophysics in myopia.
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Affiliation(s)
- Ying Xin
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China; Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Byung Soo Kang
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Yong-Ping Zheng
- Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Sze Wan Shan
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Chea-Su Kee
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.
| | - Youhua Tan
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China; Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
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Lee R, Chang RT, Wong IYH, Lai JSM, Lee JWY, Singh K. Assessment of corneal biomechanical parameters in myopes and emmetropes using the Corvis ST. Clin Exp Optom 2021; 99:157-62. [DOI: 10.1111/cxo.12341] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/04/2015] [Accepted: 08/06/2015] [Indexed: 11/27/2022] Open
Affiliation(s)
- Rachel Lee
- Stanford University School of Medicine, Palo Alto, California, USA,
| | - Robert T Chang
- Stanford University School of Medicine, Palo Alto, California, USA,
| | - Ian Y H Wong
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Jimmy S M Lai
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Jacky W Y Lee
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Kuldev Singh
- Stanford University School of Medicine, Palo Alto, California, USA,
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Sedaghat MR, Momeni-Moghaddam H, Azimi A, Fakhimi Z, Ziaei M, Danesh Z, Roberts CJ, Monfared N, Jamali A. Corneal Biomechanical Properties in Varying Severities of Myopia. Front Bioeng Biotechnol 2021; 8:595330. [PMID: 33553113 PMCID: PMC7859342 DOI: 10.3389/fbioe.2020.595330] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 12/21/2020] [Indexed: 11/20/2022] Open
Abstract
Purpose: To investigate corneal biomechanical response parameters in varying degrees of myopia and their correlation with corneal geometrical parameters and axial length. Methods: In this prospective cross-sectional study, 172 eyes of 172 subjects, the severity degree of myopia was categorized into mild, moderate, severe, and extreme myopia. Cycloplegic refraction, corneal tomography using Pentacam HR, corneal biomechanical assessment using Corvis ST and Ocular Response Analyser (ORA), and ocular biometry using IOLMaster 700 were performed for all subjects. A general linear model was used to compare biomechanical parameters in various degrees of myopia, while central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were considered as covariates. Multiple linear regression was used to investigate the relationship between corneal biomechanical parameters with spherical equivalent (SE), axial length (AXL), bIOP, mean keratometry (Mean KR), and CCT. Results: Corneal biomechanical parameters assessed by Corvis ST that showed significant differences among the groups were second applanation length (AL2, p = 0.035), highest concavity radius (HCR, p < 0.001), deformation amplitude (DA, p < 0.001), peak distance (PD, p = 0.022), integrated inverse radius (IR, p < 0.001) and DA ratio (DAR, p = 0.004), while there were no significant differences in the means of pressure-derived parameters of ORA between groups. Multiple regression analysis showed all parameters of Corvis ST have significant relationships with level of myopia (SE, AXL, Mean KR), except AL1 and AL2. Significant biomechanical parameters showed progressive reduction in corneal stiffness with increasing myopia (either with greater negative SE or greater AXL), independent of IOP and CCT. Also, corneal hysteresis (CH) or ability to dissipate energy from the ORA decreased with increasing level of myopia. Conclusions: Dynamic corneal response assessed by Corvis ST shows evidence of biomechanical changes consistent with decreasing stiffness with increasing levels of myopia in multiple parameters. The strongest correlations were with highest concavity parameters where the sclera influence is maximal.
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Affiliation(s)
| | | | - Abbas Azimi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.,Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zohreh Fakhimi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Zeynad Danesh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Cynthia J Roberts
- Ophthalmology & Visual Science, Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Naeemeh Monfared
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Alireza Jamali
- Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
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Kenia VP, Kenia RV, Pirdankar OH. Association between corneal biomechanical parameters and myopic refractive errors in young Indian individuals. Taiwan J Ophthalmol 2020; 10:45-53. [PMID: 32309124 PMCID: PMC7158932 DOI: 10.4103/tjo.tjo_15_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/06/2019] [Indexed: 12/12/2022] Open
Abstract
PURPOSE To report corneal biomechanical parameters in young myopic Indian individuals. METHODS It is a retrospective study where young myopic individuals aged between 19 and 36 years who have undergone corneal biomechanics assessment using Corvis ST between January 2017 and December 2017 were enrolled. Individuals with central corneal thickness (CCT) <500 microns, intraocular pressure (IOP) >21 mmHg, history of any systemic and ocular disease, any previous ocular surgery, high astigmatism, corneal disease such as keratoconus, poor scans quality, and individuals with any missing data were also excluded. Corneal biomechanical parameters were noted in mild to moderate and high myopia. RESULTS We analyzed the 266 eyes of 266 myopic individuals, of which 167 and 99 eyes had mild to moderate and high myopia, respectively. All the individuals were matched for age, IOP, and CCT (P > 0.05). Twenty-three of 32 parameters were similar in different degrees of myopia whereas 9 parameters were significantly different in high myopes as compared to low to moderate myopes. First applanation (A1) parameters and Vinciguerra screening parameters were similar in both the groups (P > 0.05). Second applanation (A2) parameters were similar in both the groups (P > 0.05) except A2 time, A2 deformation, amplitude (DA) (P < 0.05). Highest concavity (HC) parameters were significantly different in both the groups (P < 0.05) except HCDA, HC deflection length, and HC delta arc length (P > 0.05). CONCLUSIONS High myopic eyes showed a significantly higher maximum deflection amplitude, lesser A2 time and HC time, less A2DA, smaller HC radius than mild to moderate myopia indicating softer, more deformable corneas. However, better predictor of corneal biomechanics such as Stiffness parameters at A1 (SPA1), DA ratio max, integrated radius, and Corvis Biomechanical Index were similar among both the groups of myopia.
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Affiliation(s)
- Vaishal P Kenia
- Department of Cornea and Refractive Surgeries, Kenia Eye Hospital, Mumbai, Maharashtra, India
| | - Raj V Kenia
- Kenia Foundation, Mumbai, Maharashtra, India
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Comparison of Corneal Biomechanical Properties among Axial Myopic, Nonaxial Myopic, and Nonmyopic Eyes. BIOMED RESEARCH INTERNATIONAL 2020; 2020:8618615. [PMID: 31998799 PMCID: PMC6970496 DOI: 10.1155/2020/8618615] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/04/2019] [Accepted: 11/11/2019] [Indexed: 01/26/2023]
Abstract
Purpose To compare corneal deformation characteristics using ultra-high-speed Scheimpflug camera (Corvis ST) in patients with nonmyopic (NM), mild-to-moderate nonaxial myopic (MM), and high axial myopic (HM) eyes. Methods In this cross-sectional study, normal subjects aged >40 years with no history of ocular laser/surgery were classified according to axial length (AL) and spherical equivalence (SE) into three groups: (1) NM (SE > −0.50 D and AL < 26 mm), (2) MM (SE −6.00 D to −0.50 D and AL < 26 mm), and (3) HM (SE ≤ −6.00 D and AL ≥ 26 mm). Seven parameters including corneal deformation amplitude (CDA), inward/outward corneal applanation length, inward/outward corneal velocity (ICV and OCV), peak distance, and radius were measured. Pearson correlation and linear mixed-effects model were done. Results A total of 180 eyes were recruited. 98 eyes were NM, 30 eyes were MM, and 52 eyes were HM. There were significant correlations of OCV to the degree of refractive error (r = 0.203, p < 0.001) and AL (r = −0.242, p < 0.001). After adjusting for age, sex, intraocular pressure, and corneal thickness, there was significantly higher CDA (β = 0.07, p < 0.001), faster OCV (β = −0.08, p < 0.001), and smaller radius (β = −0.39, p=0.01) in the HM group compared to the NM group. Conclusion The higher CDA, faster OCV, and smaller radius found in the HM may suggest that these eyes have reduced ocular stiffness and may be less stable and more prone to stress.
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Wu W, Dou R, Wang Y. Comparison of Corneal Biomechanics Between Low and High Myopic Eyes-A Meta-analysis. Am J Ophthalmol 2019; 207:419-425. [PMID: 31374186 DOI: 10.1016/j.ajo.2019.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/19/2019] [Accepted: 07/13/2019] [Indexed: 11/24/2022]
Abstract
PURPOSE To compare the corneal biomechanical difference between the low myopic eyes and high myopic eyes. DESIGN Systematic review and meta-analysis. METHODS Data sources, including PubMed, Medline, EMBASE, Web of Science, and Chinese databases including Wanfang and China National Knowledge Infrastructure, were searched to find the relevant studies. Primary outcomes were corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg), and central corneal thickness (CCT) in high myopic eyes and low myopic eyes. RESULTS Eleven studies were enrolled in this study. CH and CRF were significantly higher in the low myopic eyes. The mean difference of CH was 0.73 mm Hg, 95% confidence interval (CI) [0.53 to 0.93], P < .001. The mean difference of CRF was 0.20 mm Hg, 95% CI [0.04 to 0.37], P = .02. The IOPcc and IOPg were significantly lower in the low myopic eyes. The mean difference of IOPcc was -2.53 mm Hg, 95% CI [-3.24, -1.83], P < .01. The mean difference of IOPg was -1.42 mm Hg, 95% CI [-2.26, -0.58], P = .0009. There was no significant difference between the 2 groups on CCT; the mean difference was -2.85 μm, 95% CI [-9.64.3.93], P = .41. CONCLUSION Corneal biomechanics are different in the high myopic eyes. Low CH and CRF and high IOPcc and IOPg are suggested to be associated factors for high myopia. Future studies are needed to investigate the underlying corneal structure difference that causes the low CH and CRF value in the high myopic eyes.
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Wan K, Cheung SW, Wolffsohn JS, Orr JB, Cho P. Role of corneal biomechanical properties in predicting of speed of myopic progression in children wearing orthokeratology lenses or single-vision spectacles. BMJ Open Ophthalmol 2018; 3:e000204. [PMID: 30687783 PMCID: PMC6326267 DOI: 10.1136/bmjophth-2018-000204] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Objective To determine the characteristics of children who were likely to progress rapidly and gain the greatest benefit from orthokeratology (ortho-k) treatment. Methods and analysis The files of 113 children who participated in two myopia control studies and wore either ortho-k lenses (n=62) or single-vision spectacles (SVS) (n=51) were reviewed. Baseline cycloplegic subjective refraction, central corneal thickness, axial length, keratometry, intraocular pressure, corneal biomechanical properties and 24-month axial length data were retrieved and analysed. Results Multivariate analysis showed that there was significant negative correlation between axial elongation and baseline age and corneal hysteresis (p<0.05) in the SVS group. In the ortho-k group, only baseline age was significantly and negatively associated with axial elongation (p<0.01). Conclusion Corneal biomechanical properties and baseline age can predict the rate of axial elongation in myopic children. It may be beneficial for younger myopic children with low corneal hysteresis to commence ortho-k treatment as early as possible.
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Affiliation(s)
- Kin Wan
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Sin Wan Cheung
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - James S Wolffsohn
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Janis B Orr
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
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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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The Effect of Strabismus Muscle Surgery on Corneal Biomechanics. J Ophthalmol 2018; 2018:8072140. [PMID: 30305960 PMCID: PMC6165609 DOI: 10.1155/2018/8072140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/27/2018] [Indexed: 11/22/2022] Open
Abstract
Purpose Studying the early effect of different extraocular muscle (EOM) surgeries on corneal biomechanics. Subjects and methods This is a prospective, nonrandomized, interventional study, in which 42 eyes of 29 candidates for EOM surgery for strabismus correction at Cairo university hospitals, aged 14–37 years, were recruited. All participants had measuring of the visual acuity, refraction (spherical equivalent (SE)), assessment of the EOM motility and muscle balance, sensory evaluation, fundus examination, and assessing the ocular biomechanics using the Ocular response analyzer (ORA, Reichert, INC., Depew, NY) noting the corneal hysteresis (CH) and corneal resistance factor (CRF) preoperatively. Same patients were reassessed using ORA 4 weeks postoperatively following a different standard EOM surgery (recti weakening/strengthening and inferior oblique weakening either (graded recession) according to the surgical indication, and ∆CH and ∆CRF were calculated, each is the preoperative − the postoperative value. Results ∆CH and ∆CRF = −0.78 ± 1.56 and −0.72 ± 2.15, respectively, and a highly significant difference was found between each of the pre- and postoperative CH and CRF (p < 0.001). 18 eyes had single EOM surgery, while 24 had multiple (2 or 3) EOM surgery; ∆CH in the single group = −1.28 ± 1.5, and ∆CH in the multiple group = 0.4 ± 1.49 (p=0.07). 23 eyes had EOM weakening surgery, while 18 had combined weakening and strengthening EOM surgery: ∆CH in the weakening group = −1.24 ± 1.77 and ∆CH in combined group = −0.26 ± 1.07 (p=0.04). A nonsignificant difference was found for ∆CRF (p=0.53). Conclusion A different EOM surgery has an early tendency for increase of the postoperative CH specially for muscle weakening procedures (recti recession/inferior oblique muscle weakening).
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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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Corneal hysteresis in post-radial keratotomy primary open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2018; 256:1971-1976. [DOI: 10.1007/s00417-018-4073-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 06/24/2018] [Accepted: 07/16/2018] [Indexed: 11/27/2022] Open
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Lam AKC, Leung SYY, Hon Y, Shu-Ho L, Wong KY, Tiu PK, Lam DCC. Influence of Short-Term Orthokeratology to Corneal Tangent Modulus: A Randomized Study. Curr Eye Res 2017; 43:474-481. [DOI: 10.1080/02713683.2017.1418895] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Andrew KC Lam
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Stanley YY Leung
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Ying Hon
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Lu Shu-Ho
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Kit-ying Wong
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Pui-kwan Tiu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - David CC Lam
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
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Chansangpetch S, Panpruk R, Manassakorn A, Tantisevi V, Rojanapongpun P, Hurst CP, Lin SC. Impact of Myopia on Corneal Biomechanics in Glaucoma and Nonglaucoma Patients. Invest Ophthalmol Vis Sci 2017; 58:4990-4996. [PMID: 28979996 PMCID: PMC5627793 DOI: 10.1167/iovs.17-22219] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Purpose We evaluated the impact of myopia on corneal biomechanical properties in primary open-angle glaucoma (POAG) and nonglaucoma patients, and the effect of modification of glaucoma on myopic eyes. Methods This cross-sectional study included 66 POAG eyes (33 myopia, 33 nonmyopia) and 66 normal eyes (33 myopia, 33 nonmyopia). Seven corneal biomechanical parameters were measured by ultra-high-speed Scheimpflug imaging, including corneal deformation amplitude (CDA), inward/outward corneal applanation length (ICA, OCA), inward/outward corneal velocity (ICV, OCV), radius, and peak distance (PD). Results Mean age (SD) of the 65 male (49%) and 67 female (51%) patients was 59 (9.82) years. Myopia was associated with significantly higher CDA (adjusted effect = 0.104, P = 0.001) and lower OCV (adjusted effect = -0.105, P < 0.001) in the POAG group. Within the nonglaucoma group, myopic eyes had a significantly lower OCV (adjusted effect = -0.086, P < 0.001) and higher CDA (adjusted effect = 0.079, P = 0.001). All parameters except PD suggested that glaucoma modified the effect of myopia on corneal biomechanics. Percentage differences in the adjusted myopic effect between POAG and nonglaucoma patients was 31.65, 27.27, 31.65, 50.00, 22.09, and 60.49 for CDA, ICA, OCA, ICV, OCV, and radius, respectively. Conclusions Myopia had a significant impact on corneal biomechanical properties in the POAG and nonglaucoma groups. The differences in corneal biomechanical parameters suggest that myopia is correlated with significantly lower ocular rigidity. POAG may enhance the effects of myopia on most of these parameters.
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Affiliation(s)
- Sunee Chansangpetch
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.,Department of Ophthalmology, University of California, San Francisco Medical School, San Francisco, California, United States
| | - Rawiphan Panpruk
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Anita Manassakorn
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Visanee Tantisevi
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Prin Rojanapongpun
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Cameron P Hurst
- Biostatistics Center, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Shan C Lin
- Department of Ophthalmology, University of California, San Francisco Medical School, San Francisco, California, United States
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Miki A, Maeda N, Asai T, Ikuno Y, Nishida K. Measurement repeatability of the dynamic Scheimpflug analyzer. Jpn J Ophthalmol 2017; 61:433-440. [PMID: 28983780 DOI: 10.1007/s10384-017-0534-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 07/28/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To evaluate the repeatability of corneal deformation parameters measured using a dynamic Scheimpflug analyzer and the impact of baseline clinical factors on the repeatability of each parameter. STUDY DESIGN Retrospective, cross-sectional study. METHODS Forty-eight eyes (48 healthy subjects; mean age, 49.0 ± 19.5 years) underwent repeated examinations with the Scheimpflug analyzer to evaluate the test-retest variability. The intraclass correlation coefficient (ICC) and repeatability coefficient as indicators of variability were computed for 35 parameters measured with the Scheimpflug analyzer. The associations between the magnitude of the test-retest variability and baseline factors, such as age, axial length (AL), intraocular pressure (IOP), and central corneal thickness (CCT), were analyzed. RESULTS The test-retest repeatability was excellent for 22 (62.9%) of 35 parameters (ICC ≥ 0.75), good for seven (20%), (ICC ≥ 0.6), fair for four (11.4%), (ICC ≥ 0.4), and poor for two (5.7%) parameters (ICC < 0.4). Age was associated positively with the magnitude of variability in 13 (37.1%) parameters; measurement variability was affected significantly by AL (5 parameters, 14.3%) and CCT (7 parameters, 20%) but, except for one parameter not by IOP. CONCLUSION Most parameters of the dynamic Scheimpflug analyzer showed favorable measurement reliability in healthy subjects. However, six parameters showed poor-to-fair repeatability. Age, AL, and CCT significantly affected the repeatability of several parameters. These results should be considered when clinicians use this device in clinical practice.
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Affiliation(s)
- Atsuya Miki
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan.
| | - Naoyuki Maeda
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Tomoko Asai
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Yasushi Ikuno
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Kohji Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
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Correlation of Corneal Biomechanical Stiffness With Refractive Error and Ocular Biometry in a Pediatric Population. Cornea 2017; 36:1221-1226. [DOI: 10.1097/ico.0000000000001290] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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İnceoğlu N, Emre S, Ulusoy MO. Investigation of corneal biomechanics at moderate to high refractive errors. Int Ophthalmol 2017; 38:1061-1067. [DOI: 10.1007/s10792-017-0560-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022]
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Sharifipour F, Panahi-Bazaz M, Bidar R, Idani A, Cheraghian B. Age-related variations in corneal biomechanical properties. J Curr Ophthalmol 2016; 28:117-22. [PMID: 27579455 PMCID: PMC4992116 DOI: 10.1016/j.joco.2016.05.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/15/2016] [Accepted: 05/15/2016] [Indexed: 11/26/2022] Open
Abstract
Purpose To determine age-related changes in corneal viscoelastic properties in healthy individuals. Methods This observational cross-sectional study was performed at the Department of Ophthalmology, Imam Khomeini Hospital, Ahvaz, Iran and included 302 healthy individuals in 6 age decades (range: 10–69 years). After complete ocular examination, corneal viscoelastic properties were measured by ocular response analyzer and central corneal thickness (CCT) by an ultrasonic pachymeter. Our main outcome measures were corneal viscoelastic properties in different age groups. Results Corneal hysteresis (CH) and corneal resistance factor (CRF) showed a significant negative correlation with age (P < 0.001 for both, r = −0.353 and r = −0.246, respectively). Female gender had significantly higher CH (P = 0.017) and CRF (P = 0.019). CH and CRF were significantly correlated (P < 0.001, r = 0.821). CCT showed a biphasic pattern with significantly higher thicknesses before 20 and after 50 years of age. CH and CRF were significantly correlated with CCT (P < 0.001 for both, r = 0.21 and r = 0.26, respectively) and intraocular pressure (IOP) (P < 0.001 for both, r = −0.474 and r = 0.598, respectively). Corneal-compensated IOP (IOPcc) was significantly higher after age 40 compared to age group <20 (p < 0.045). Goldmann-correlated IOP (IOPg) was significantly correlated with CCT (P = 0.001, r = 0.193), while IOPcc showed no correlation with CCT (P = 0.265, r = 0.062). CH was significantly higher in hyperopic eyes compared to emmetropic eyes (P = 0.009) and myopic eye (P < 0.001). Conclusions In this study, there was a decrease in CH and CRF with an increase in age. Hyperopia and female gender are associated with higher CH and CRF. CCT is higher toward the extremes of life and is significantly correlated with CH and CRF.
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Affiliation(s)
- Farideh Sharifipour
- Department of Ophthalmology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | - Roghayeh Bidar
- Department of Ophthalmology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Aida Idani
- Iran University of Medical Sciences, Tehran, Iran
| | - Bahman Cheraghian
- Department of Biostatics and Epidemiology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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Abstract
PURPOSE To evaluate the influence of pterygium on corneal biomechanical properties as measured by the ocular response analyzer (ORA). METHODS ORA measurements of 48 eyes with primary nasal pterygium were compared with those of healthy fellow eyes. The mean age of the patients was 46.6 ± 18.9 years. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) were obtained for each subject by using the ORA (Reichert Ophthalmic Instruments, Depew, NY). RESULTS CH and CRF were significantly lower in the eyes with pterygium than in the healthy fellow eyes (p1 = 0.011, p2 = 0.014, respectively). On the other hand, there were no significant differences between the eyes with pterygium and healthy fellow eyes concerning IOPg and IOPcc (p1 = 0.948, p2 = 0.129, respectively). CONCLUSIONS The present study showed that biomechanical properties measured by ORA were affected by pterygium. The eyes with primary nasal pterygium had lower CH and CRF than healthy fellow eyes. Therefore, the effect of pterygium should be taken into account in order to make correct diagnoses by ORA.
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Affiliation(s)
- Veysi Öner
- a Ophthalmology Department , Recep Tayyip Erdoğan University Medical School , Rize , Turkey
| | - Mehmet Taş
- b Malatya State Hospital , Malatya , Turkey
| | | | - Asker Bulut
- c Ophthalmology Department , Recep Tayyip Erdoğan University Medical School Education and Research Hospital , Rize , Turkey
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Jin JX, Hua WJ, Jiang X, Wu XY, Yang JW, Gao GP, Fang Y, Pei CL, Wang S, Zhang JZ, Tao LM, Tao FB. Effect of outdoor activity on myopia onset and progression in school-aged children in northeast China: the Sujiatun Eye Care Study. BMC Ophthalmol 2015; 15:73. [PMID: 26152123 PMCID: PMC4495846 DOI: 10.1186/s12886-015-0052-9] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 06/05/2015] [Indexed: 11/15/2022] Open
Abstract
Background Due to its high prevalence and associated sight-threatening pathologies, myopia has emerged as a major health issue in East Asia. The purpose was to test the impact on myopia development of a school-based intervention program aimed at increasing the time student spent outdoors. Methods A total of 3051 students of two primary (grades 1-5, aged 6-11) and two junior high schools (grades 7-8, aged 12-14) in both urban and rural Northeast China were enrolled. The intervention group (n = 1735) unlike the control group (n = 1316) was allowed two additional 20-min recess programs outside the classroom. A detailed questionnaire was administered to parents and children. Uncorrected visual acuity (UCVA) was measured using an E Standard Logarithm Vision Acuity Chart (GB11533-2011) at baseline, 6-month and 1-year intervals. A random subsample (n = 391) participated in the clinic visits and underwent cycloplegia at the beginning and after 1 year. Results The mean UCVA for the entire intervention group was significantly better than the entire control group after 1 year (P < 0.001). In the subgroup study, new onset of myopia and changes in refractive error towards myopia were direction during the study period was significantly lower in the intervention group than in the control group (3.70 % vs. 8.50 %, P = 0.048; -0.10 ± 0.65 D/year vs. -0.27 ± 0.52 D/year, P = 0.005). Changes in axial length and IOP were also significantly lower following the intervention group (0.16 ± 0.30 mm/year vs. 0.21 ± 0.21 mm/year, P = 0.034; -0.05 ± 2.78 mmHg/year vs. 0.67 ± 2.21 mmHg/year, P = 0.006). Conclusions Increasing outdoor activities prevented myopia onset and development, as well as axial growth and elevated IOP in children. Trial registration Current controlled trials NCT02271373. Electronic supplementary material The online version of this article (doi:10.1186/s12886-015-0052-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ju-Xiang Jin
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China.
| | - Wen-Juan Hua
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China.
| | - Xuan Jiang
- Health Center for Elementary and Middle School Students of Sujiatun District, Shenyang, Liaoning, China.
| | - Xiao-Yan Wu
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China.
| | - Ji-Wen Yang
- Shenyang Aier Eye Hospital, Shenyang, Liaoning, China.
| | - Guo-Peng Gao
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China.
| | - Yun Fang
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China.
| | - Chen-Lu Pei
- Department of Ophthalmology, the Second Hospital of Anhui Medical University, Hefei, Anhui, China.
| | - Song Wang
- Department of Ophthalmology, the Second Hospital of Anhui Medical University, Hefei, Anhui, China.
| | - Jie-Zheng Zhang
- Education Bureau of Sujiatun District, Shenyang, Liaoning, China.
| | - Li-Ming Tao
- Department of Ophthalmology, the Second Hospital of Anhui Medical University, Hefei, Anhui, China.
| | - Fang-Biao Tao
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, 81st Meishan Road, Hefei, 230032, Anhui Province, P.R China. .,Anhui Provincial Key Laboratory of Population Health & Aristogenics, Hefei, Anhui, China.
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Yülek F, Gerçeker S, Akçay E, Saraç Ö, Çağıl N. Corneal biomechanics in steroid induced ocular hypertension. Cont Lens Anterior Eye 2015; 38:181-4. [DOI: 10.1016/j.clae.2015.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 01/26/2015] [Accepted: 01/26/2015] [Indexed: 11/28/2022]
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Öner V, Taş M, Özkaya E, Oruç Y. Effect of pathological myopia on biomechanical properties: a study by ocular response analyzer. Int J Ophthalmol 2015; 8:365-8. [PMID: 25938057 DOI: 10.3980/j.issn.2222-3959.2015.02.27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 07/23/2014] [Indexed: 12/13/2022] Open
Abstract
AIM To evaluate the ocular response analyzer (ORA) measurements of patients with pathological myopia in comparison with those of emmetropic control subjects, and to investigate the correlation between these ORA measurements and spherical equivalent (SE). METHODS Measurements of 53 eyes of 53 subjects with pathological myopia (SE>-6.00 D) were compared with those of 60 eyes of 60 emmetropic controls. Corneal hysteresis (CH), corneal resistance factor (CRF), noncontact tonometer intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) were obtained for each subject. The refractive error value was determined as SE via a cycloplegic refraction test. RESULTS The mean age was 54.1±18.9y (ranging from 5 to 88) in the pathological myopic group and 56.2±19.0y (ranging from 6 to 89) in the control group. There were no significant differences between the groups concerning age and sex. CH and CRF were significantly lower in the pathological myopic group than in the control group (P<0.001, P=0.005, respectively). IOPcc and IOPg were significantly higher in the pathological myopic group than in the control group (P<0.001, P=0.009, respectively). There were significantly positive correlations between CH and SE (r=0.565, P<0.001) and between CRF and SE (r=0.364, P=0.007). There were significantly negative correlations between IOPcc and SE (r=-0.432, P=0.001) and between IOPg and SE (r=-0.401, P=0.003). CONCLUSION The present study displayed that pathological myopia affected biomechanical properties measured by ORA. The results of corneal biomechanical properties measured by ORA may need to be appreciated by taking refraction into account. Further, pathological myopia might be related with the increased IOP.
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Affiliation(s)
- Veysi Öner
- Department of Ophthalmology, Recep Tayyip Erdoğan University Medical School, Rize 53100, Turkey
| | - Mehmet Taş
- Department of Ophthalmology, Malatya State Hospital, Malatya 44000, Turkey
| | - Erdal Özkaya
- Department of Ophthalmology, Malatya State Hospital, Malatya 44000, Turkey
| | - Yavuz Oruç
- Department of Ophthalmology, Recep Tayyip Erdoğan University Education and Research Hospital, Rize 53100, Turkey
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Wong YZ, Lam AKC. The Roles of Cornea and Axial Length in Corneal Hysteresis among Emmetropes and High Myopes: A Pilot Study. Curr Eye Res 2014; 40:282-9. [DOI: 10.3109/02713683.2014.922193] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Corneal biomechanical properties in different ocular conditions and new measurement techniques. ISRN OPHTHALMOLOGY 2014; 2014:724546. [PMID: 24729900 PMCID: PMC3960740 DOI: 10.1155/2014/724546] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 11/26/2013] [Indexed: 12/04/2022]
Abstract
Several refractive and therapeutic treatments as well as several ocular or systemic diseases might induce changes in the mechanical resistance of the cornea. Furthermore, intraocular pressure measurement, one of the most used clinical tools, is also highly dependent on this characteristic. Corneal biomechanical properties can be measured now in the clinical setting with different instruments. In the present work, we review the potential role of the biomechanical properties of the cornea in different fields of ophthalmology and visual science in light of the definitions of the fundamental properties of matter and the results obtained from the different instruments available. The body of literature published so far provides an insight into how the corneal mechanical properties change in different sight-threatening ocular conditions and after different surgical procedures. The future in this field is very promising with several new technologies being applied to the analysis of the corneal biomechanical properties.
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del Buey MA, Lavilla L, Ascaso FJ, Lanchares E, Huerva V, Cristóbal JA. Assessment of corneal biomechanical properties and intraocular pressure in myopic spanish healthy population. J Ophthalmol 2014; 2014:905129. [PMID: 24719755 PMCID: PMC3955599 DOI: 10.1155/2014/905129] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/10/2014] [Indexed: 11/17/2022] Open
Abstract
Purpose. To examine biomechanical parameters of the cornea in myopic eyes and their relationship with the degree of myopia in a western healthy population. Methods. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated intraocular pressure (IOP), and corneal compensated IOP (IOPcc) were measured using the ocular response analyzer (ORA) in 312 eyes of 177 Spanish subjects aged between 20 and 56 years. Refraction was expressed as spherical equivalent (SE), which ranged from 0 to -16.50 diopters (D) (mean: -3.88 ± 2.90 D). Subjects were divided into four groups according to their refractive status: group 1 or control group: emmetropia (-0.50 ≤ SE < 0.50); group 2: low myopia (-0.75 ≤ SE < 3.00 D); group 3: moderate myopia (-3.00 ≤ SE ≤ -6.00 D); and group 3: high myopia (SE greater than -6.00 D). We analyzed the relationship between corneal biomechanics measured with ORA and SE. Results. CH in the emmetropia, low myopia, moderate myopia, and high myopia groups was 11.13 ± 0.98, 11.49 ± 1.25, 10.52 ± 1.54, and 10.35 ± 1.33 mmHg, respectively. CH in the highly myopic group was significantly lower than that in the emmetropic group (P = 0.07) and low myopic group (P = 0.035); however, there were no differences with the moderate myopic group (P = 0.872). There were no statistically significant differences regarding IOP among the four groups (P > 0.05); nevertheless, IOPcc was significantly higher in the moderately myopic (15.47 ± 2.47 mmHg) and highly myopic (16.14 ± 2.59 mmHg) groups than in the emmetropia (15.15 ± 2.06 mmHg) and low myopia groups (14.53 ± 2.37 mmHg). No correlation between age and the measured parameters was found. CH and IOPcc were weakly but significantly correlated with SE (r = 0.171, P = 0.002 and r = -0.131, P = 0.021, resp.). Conclusions. Present study showed only a very weak, but significant, correlation between CH and refractive error, with CH being lower in both moderately and highly myopic eyes than that in the emmetropic and low myopic eyes. These changes in biomechanical properties of the cornea may have an impact on IOP measurement, increasing the risk of glaucoma.
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Affiliation(s)
- María A. del Buey
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - Laura Lavilla
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
| | - Francisco J. Ascaso
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - Elena Lanchares
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
- Aragón Institute for Engineering Research (I3A), University of Zaragoza, CIBER on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| | - Valentín Huerva
- Department of Ophthalmology, Arnau de Vilanova University Hospital and IRB-Lleida, Avenida Rovira Roure 80, Lleida, Spain
| | - José A. Cristóbal
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
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Ortiz S, Mena L, Rio-San Cristobal A, Martin R. Relationships between central and peripheral corneal thickness in different degrees of myopia. JOURNAL OF OPTOMETRY 2014; 7:44-50. [PMID: 24646900 PMCID: PMC3938742 DOI: 10.1016/j.optom.2013.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/07/2013] [Accepted: 02/07/2013] [Indexed: 05/03/2023]
Abstract
PURPOSE To analyze the relationship between the central corneal thickness (CCT) and mid-peripheral corneal thickness (PCT) with the degree of myopia [axial length (AL) and spherical equivalent refractive error (SE)]. METHODS 175 right myopic eyes from 175 patients were divided according to the degree of SE: group #1 (n=76, <6.00 D), group #2 (n=72, between 6.00 and 12.00 D) and group #3 (n=27, >12.00 D). The CCT and PCT (3mm from the apex to the superior, inferior, nasal and temporal locations) were measured with the Orbscan-II. Relative peripheral index (RPI) was calculated by dividing the PCT by the CCT. The AL was measured with the IOL Master, and the SE was obtained with subjective refraction. RESULTS AL was 25.18±1.16 mm, 26.59±1.26 mm and 29.45±2.58 mm and SE was -3.31±1.40 D, -8.32±1.64 D and -16.44±4.48 D for groups #1, #2 and #3, respectively. Non-statistically significant differences in central and peripheral corneal thickness were found between groups (P>0.05 ANOVA). Non-significant relationship was found between central and peripheral corneal thickness with the AL and SE in the three study groups and in the total sample (r<0.24; P>0.05). The RPI values were similar between groups without significant difference between groups (P>0.05 ANOVA). Linear relationship was found between RPI superior location in group #2 (r=-0.23; P=0.04) and RPI nasal location in group #3 with the EE (r=0.41; P=0.03). CONCLUSION There are no significant differences among low, moderate and extremely myopic eyes related to the CCT and PCT. Corneal thickness is very similar in myopic eyes with small differences that are not clinically relevant to myopic patient management.
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Affiliation(s)
- Sara Ortiz
- Optometry Research Group, IOBA-Eye Institute, University of Valladolid, Valladolid, Spain
| | - Laura Mena
- Optometry Research Group, IOBA-Eye Institute, University of Valladolid, Valladolid, Spain
| | - Ana Rio-San Cristobal
- Optometry Research Group, IOBA-Eye Institute, University of Valladolid, Valladolid, Spain
| | - Raul Martin
- Optometry Research Group, IOBA-Eye Institute, University of Valladolid, Valladolid, Spain; Department of Physics TAO, School of Optometry, University of Valladolid, Valladolid, Spain.
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Ruiseñor Vázquez PR, Delrivo M, Bonthoux FF, Pförtner T, Galletti JG. Combining ocular response analyzer metrics for corneal biomechanical diagnosis. J Refract Surg 2013; 29:596-602. [PMID: 23848186 DOI: 10.3928/1081597x-20130710-01] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 04/25/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate corneal biomechanical properties in non-keratoconic myopic eyes and to identify descriptors for improving the specificity of the Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY) testing for subclinical keratoconus detection. METHODS Observational case series of 52 non-keratoconic non-myopic eyes and 97 non-keratoconic myopic eyes (spherical equivalent < -5 diopters [D]) in dataset 1 and 87 non-keratoconic eyes and 73 eyes with subclinical keratoconus in dataset 2. Examination included corneal topography, tomography, and biomechanical testing with the ORA. Receiver operating characteristic curves and logistic regression were used to identify optimal combinations of biomechanical indices for keratoconus detection. Main outcome measures were corneal thickness-corrected hysteresis (DifCH) and resistance factor (DifCRF), the difference between these two (CH-CRF), and the diagnostic performance of their combinations. RESULTS Compared to non-keratoconic non-myopic eyes, non-keratoconic myopic eyes with flat corneas (average corneal power < 44.0 D) had reduced DifCH (mean ± standard deviation, 0.11 ± 1.27 vs -0.79 ± 1.50, P < .01) and DifCRF (0.24 ± 1.16 vs -0.70 ± 1.59, P < .01) values, whereas non-keratoconic myopic eyes with steep corneas showed no difference. Keratoconic eyes exhibited lower DifCH and DifCRF values than non-keratoconic myopic eyes. Combinations of DifCH, DifCRF, and CH-CRF had increased specificity (> 80%) for subclinical keratoconus compared to the DifCRF index alone (71%). CONCLUSIONS In biomechanical keratoconus screening, some non-keratoconic myopic eyes show altered ocular biomechanical properties and are identified as false-positive cases. The low specificity of DifCRF when dealing with these non-keratoconic eyes could be improved by considering additional biomechanical descriptors such as DifCH and CH-CRF, which seem to be indicative of the aforementioned biomechanical profile.
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Weise KK, Kaminski B, Melia M, Repka MX, Bradfield YS, Davitt BV, Johnson DA, Kraker RT, Manny RE, Matta NS, Schloff S. Intraobserver reliability of contact pachymetry in children. J AAPOS 2013; 17:144-8. [PMID: 23622447 PMCID: PMC3639436 DOI: 10.1016/j.jaapos.2012.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/02/2012] [Accepted: 11/06/2012] [Indexed: 12/27/2022]
Abstract
BACKGROUND Central corneal thickness (CCT) is an important measurement in the treatment and management of pediatric glaucoma and potentially of refractive error, but data regarding reliability of CCT measurement in children are limited. The purpose of this study was to evaluate the reliability of CCT measurement with the use of handheld contact pachymetry in children. METHODS We conducted a multicenter intraobserver test-retest reliability study of more than 3,400 healthy eyes in children aged from newborn to 17 years by using a handheld contact pachymeter (Pachmate DGH55; DGH Technology Inc, Exton, PA) in 2 clinical settings--with the use of topical anesthesia in the office and with the patient under general anesthesia in a surgical facility. RESULTS The overall standard error of measurement, including only measurements with standard deviation ≤5 μm, was 8 μm; the corresponding coefficient of repeatability, or limits within which 95% of test-retest differences fell, was ±22.3 μm. However, standard error of measurement increased as CCT increased, from 6.8 μm for CCT less than 525 μm, to 12.9 μm for CCT 625 μm and greater. The standard error of measurement including measurements with standard deviation >5 μm was 10.5 μm. Age, sex, race/ethnicity group, and examination setting did not influence the magnitude of test-retest differences. CONCLUSIONS CCT measurement reliability in children via the Pachmate DGH55 handheld contact pachymeter is similar to that reported for adults. Because thicker CCT measurements are less reliable than thinner measurements, a second measure may be helpful when the first exceeds 575 μm. Reliability is also improved by disregarding measurements with instrument-reported standard deviations >5 μm.
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Affiliation(s)
- Katherine K Weise
- University of Alabama at Birmingham School of Optometry, Birmingham, Alabama, USA.
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Abstract
PURPOSE To describe intraocular pressure (IOP) and central corneal thickness (CCT) in ethnically diverse, myopic young adults enrolled in COMET (the Correction of Myopia Evaluation Trial) and their association with ocular and demographic factors. METHODS IOP (Goldmann tonometry), CCT (handheld pachymetry), refractive error (cycloplegic autorefraction), and ocular components (A-scan ultrasonography) were measured in 385 of the original 469 subjects (mean age = 20.3 ± 1.3 years). Summary statistics for descriptive analysis, Pearson correlation coefficients, and linear regression models to formally test the association of IOP and CCT with other covariates were used. RESULTS Mean IOP was 15.1 ± 0.1 mm Hg and differed by ethnicity and CCT but did not vary by gender, magnitude of myopia, or vitreous chamber depth (VCD). Adjusting for CCT, IOP in black participants was 1.8 mm Hg higher than in Hispanics (p = 0.0001) and 0.8 mm Hg higher than in whites (p = 0.03). Mean CCT was 562.4 ± 1.8 μm and differed by ethnicity, VCD, and IOP after adjusting for covariates. Blacks had thinner corneas than Asians, whites, and Hispanics, with adjusted differences of 15.4, 11.8, and 15.3 μm (p = 0.03, < 0.01 and < 0.01), respectively. Eyes with shorter VCD (<17.8 mm) had 8.0-μm thinner CCT (p = 0.03). CCT did not vary by gender or magnitude of myopia. Overall, a modest positive correlation (r = 0.25, P < 0.0001) was found between IOP and CCT, which varied by ethnicity in Asians (r = 0.47; p = 0.008), blacks (r = 0.29; p = 0.002), and whites (r = 0.24; p = 0.002). CONCLUSIONS Myopic, black young adults had higher IOP and thinner corneas relative to other ethnic groups, suggesting that evaluation of these parameters during routine examination of these individuals should begin at a young age. Their thinner CCT should also be considered in evaluations for refractive surgery.
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Rhew JY, Choi KR. Corneal Biomechanical Properties of Normal Tension Glaucoma in Young Patients Evaluated with the Ocular Response Analyzer. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2013. [DOI: 10.3341/jkos.2013.54.2.280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Jin Young Rhew
- Department of Ophthalmology, Ewha Womans University School of Medicine, Ewha Institute of Ophthalmology and Optometry, EIOO, Seoul, Korea
| | - Kyu Ryong Choi
- Department of Ophthalmology, Ewha Womans University School of Medicine, Ewha Institute of Ophthalmology and Optometry, EIOO, Seoul, Korea
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