The Roles of Cornea and Axial Length in Corneal Hysteresis among Emmetropes and High Myopes: A Pilot Study

Wong, Yin-Zhi; Lam, Andrew

doi:10.3109/02713683.2014.922193

Cited by 30 publications

(32 citation statements)

References 52 publications

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“…Our new findings included identification of less viscous damping and less whole eye movement of myopic eyes. Several previous studies using the ORA have reported lower CH values in myopic eyes, 9,21,22,24 which agrees with the current study in which less viscous damping capacity was seen in eyes with a longer axial length.…”

Section: Axial Lengthsupporting

confidence: 92%

“…In addition to ocular pathologies, the corneal biomechanical parameters are associated with a range of ocular and systemic factors. The ORA parameters are affected by various baseline factors such as refraction, 8,9 axial length, [21][22][23][24] age, 23 IOP, 23 corneal curvature, 23 and central corneal thickness (CCT). 25 Parameters measured with the Corvis ST are associated with the axial length, 26 age, 27,28 diabetes, 29 IOP, 13,25,[30][31][32] corneal curvature, 26,33 and CCT.…”

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confidence: 99%

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Factors Associated With Corneal Deformation Responses Measured With a Dynamic Scheimpflug Analyzer

Miki

Maeda

Ikuno

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. The purpose of this study was to clarify correlations between corneal deformation parameters measured with a dynamic Scheimpflug analyzer and baseline factors such as axial length, intraocular pressure (IOP), age, central corneal thickness (CCT), and corneal curvature.METHODS. Ninety-six eyes of 96 healthy subjects (mean 55.2 6 16.1 years of age) were examined using a dynamic Scheimpflug analyzer. Eighteen of 35 deformation parameters were selected for analyses based on measurement reliability and clinical relevance. The associations between corneal deformation parameters and axial length, IOP, age, CCT, and average corneal power were evaluated using multivariate regression analyses.RESULTS. Deformation parameters were correlated significantly with axial length (n ¼ 13), IOP (n ¼ 13), age (n ¼ 8), and CCT (n ¼ 6) in the multivariate models. Longer axial length corresponded with greater corneal deformability, less viscous damping, and less movement of the entire eye. Higher IOP was associated with greater corneal resistance and less movement of the entire eye. Older age was associated with less corneal deformability and greater movement of the entire eye. Corneal curvature was correlated significantly with only three deformation parameters.CONCLUSIONS. This study clarified the substantial impact of axial length, age, and IOP on the biomechanical responses of the cornea and the entire eye. In contrast, corneal curvature did not affect most of the deformation parameters. The current results confirmed the importance of corneal biomechanics, especially in eyes with longer axial length and in older subjects.

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Section: Axial Lengthsupporting

confidence: 92%

mentioning

confidence: 99%

Factors Associated With Corneal Deformation Responses Measured With a Dynamic Scheimpflug Analyzer

Miki

Maeda

Ikuno

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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“…Beyond that, axial length as a more direct variable related to tissue extension and reflection of ocular rigidity [ 15 ], was significantly associated with corneal biomechanical properties. Several studies have confirmed that axial elongation was significantly associated with lower CH [ 16 – 18 ]. In addition, CH was significantly associated with corneal curvature, which means flatter corneas are associated with lower CH readings [ 16 , 19 ].…”

Section: Discussionmentioning

confidence: 99%

Changes in Corneal Biomechanical Properties after Long-Term Topical Prostaglandin Therapy

Chen

et al. 2016

PLoS ONE

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ObjectiveTo compare corneal biomechanical properties, measured by a newly developed tonometer (Corneal Visualization Scheimpflug Technology, Corvis ST), in untreated primary open angle glaucoma (POAG) patients, POAG patients with long-term topical prostaglandin analog (PGA) therapy and in normal controls. Further is to investigate the potential effects of PGA on corneal biomechanics.MethodsIn this case-control study, 35 consecutive medication naïve eyes with POAG, 34 POAG eyes with at least 2 years treatment by PGA and 19 normal eyes were included. Intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters, including deformation amplitude (DA), applanation time (AT1 and AT2), applanation length (AL1 and AL2), applanation velocity (AV1 and AV2), and peak distance and radius were measured using Corvis ST. Axial length and corneal curvature were measured with partial coherence interferometry (IOLMaster, Zeiss, Germany). General linear model analysis was performed to investigate the corneal biomechanical property changes among the normal controls, newly diagnosed POAG patients and POAG patients with long-term PGA treatment, and among the subgroups of different types of PGA treatment, including bimatoprost, latanoprost and travoprost. Furthermore, pairwise comparisons using Bonferroni correction for least squares means were employed.ResultsAT1 (p<0.0001), AV1 (p<0.0001), AT2 (p = 0.0001), AV2 (p<0.0001) and DA (p = 0.0004) in newly diagnosed glaucoma patients were significantly different from those in normal subjects and in patients underwent at least 2 years topical PGA therapy after adjusting for age and gender. After adjusting for age, gender, IOP, CCT, axial length and corneal curvature, a significant difference was detected for DA between glaucoma patients without PGA treatment and patients with long-term PGA therapy (p = 0.0387). Furthermore, there were no statistical significant differences in all of the corneal biomechanical parameters among the 3 types of PGA therapy subgroups, namely bimatoprost, latanoprost and travoprost.ConclusionsSignificant changes in corneal deformation parameters were found among untreated POAG patients, POAG patients with long-term topical PGA therapy and normal controls. Long-term topical PGA treatment might have a direct effect on corneal biomechanical properties in addition to the indirect effect owing to the PGA-induced IOP reduction and CCT decrease on corneal dynamic properties.

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“…The Ocular Response Analyzer (ORA) was the first instrument launched and is extensively used to measure corneal biomechanical properties in terms of corneal hysteresis (CH) and corneal resistance factor (CRF). 10 – 14 The ultra-high speed Scheimpflug camera (Corvis ST) is a new device with precise, repeatable, and reproducible measurements of corneal biomechanical properties. The device provides quantitative information, including the magnitude and direction of the displacement of the corneal apex.…”

mentioning

confidence: 99%

Impact of Myopia on Corneal Biomechanics in Glaucoma and Nonglaucoma Patients

Chansangpetch

Panpruk

Manassakorn

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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PurposeWe 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.MethodsThis 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).ResultsMean 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.ConclusionsMyopia 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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The Roles of Cornea and Axial Length in Corneal Hysteresis among Emmetropes and High Myopes: A Pilot Study

Abstract: High myopes exhibited lower CH than emmetropes. Although CH had stronger correlation with FST than AL, it might contain the biomechanical properties of components other than the cornea.

Cited by 30 publications

References 52 publications

Factors Associated With Corneal Deformation Responses Measured With a Dynamic Scheimpflug Analyzer

Factors Associated With Corneal Deformation Responses Measured With a Dynamic Scheimpflug Analyzer

Changes in Corneal Biomechanical Properties after Long-Term Topical Prostaglandin Therapy

Impact of Myopia on Corneal Biomechanics in Glaucoma and Nonglaucoma Patients

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