scholarly journals Investigation of corneal biomechanical properties using the CORVIS ST device (Oculus, Germany) in patients with myopia and myopic astigmatism

2020 ◽  
pp. 20-28
Author(s):  
V.D. Antonuk ◽  
◽  
T.S. Kuznetsova ◽  
Keyword(s):  
Excimer Laser ◽  
Refractive Surgery ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Vision Correction ◽  
Laser Vision ◽  
Laser Refractive Surgery ◽  
Myopic Astigmatism ◽  
Corneal Biomechanical Properties

Purpose. To evaluate the corneal biomechanical properties using the CORVIS ST device (Oculus, Germany) in patients with myopia and myopic astigmatism with intact cornea as well as in patients with myopia and myopic astigmatism who underwent excimer laser refractive surgery using femtolaser or microkeratome. Material and methods. Totally the study included 65 patients aged 18 years to 56 years with myopia and myopic astigmatism of various degrees were examined. They were scheduled for excimer laser refractive surgery after laser refractive surgery in different periods from 5 days to 5 years. Among the additional methods of examination, all patients were measured the biomechanical properties of the cornea using a CORVIS ST device (Oculus, Germany). Results. After excimer laser refractive surgery performing for myopia and myopic astigmatism correction, indicators of the corneal biomechanical properties, namely indicators describing stiffness and elasticity were changed, as well as IOP indicators. Conclusion. The biomechanical properties of the cornea, such as stiffness and elasticity, can be assessed using the CORVIS ST device (Oculus, Germany). After excimer laser vision correction of myopia and myopic astigmatism, corneal stiffness and elasticity decreases. IOP value in patients after excimer laser correction of myopia and myopic astigmatism decreases. It is associated with a decrease in corneal thickness but is not associated with a true decrease in IOP. Key words: biomechanical properties of the cornea, refractive surgery, excimer laser vision correction, femtolaser vision correction, myopia, myopic astigmatism.

Assessment of changes in the biomechanical properties of the cornea after FemtoLASIK surgery

2021 ◽  
pp. 121-125
Author(s):  
E.V. Boiko ◽  
◽  
E.S. Togo ◽  
I.B. Litvin ◽  
A.B. Kachanov ◽  
...  
Keyword(s):  
Key Words ◽  
Refractive Surgery ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Vision Correction ◽  
Before And After ◽  
Keratorefractive Surgery

Purpose. The aim of the study is to investigate the biomechanical properties of the cornea before and after FemtoLASIK in patients with myopia. Material and methods. 24 patients (42 eyes) underwent refractive vision correction using the FemtoLASIK method. The Oculus CORVIS ST ® device (Oculus, Germany) was used to assess the biomechanical properties of the cornea. Results. A statistically significant decrease in the rigidity and strength of the cornea was noted after keratorefractive surgery. Conclusion. Refractive surgery using FemtoLASIK technology leads to a decrease in the rigidity of the cornea, and therefore to a reduction in its framework properties. Key words: refractive surgery, FemtoLASIK, myopia, laser correction, biomechanical properties of the cornea, Oculus CORVIS ST ®.

scholarly journals The changes of corneal biomechanical properties with long-term treatment of prostaglandin analogue measured by Corvis ST

2020 ◽  
Author(s):  
Na Wu ◽  
Yuhong Chen ◽  
Yaping Yang ◽  
Xinghuai Sun
Keyword(s):  
Open Angle Glaucoma ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Term Treatment ◽  
Prostaglandin Analogue ◽  
Corvis St ◽  
Long Term Treatment ◽  
Corneal Biomechanical Properties

Abstract Background: To investigate the corneal biomechanical changes in primary open angle glaucoma (POAG) patients treated with long-term prostaglandin analogue (PGA). Methods: 111 newly diagnosed POAG patients, including 43 high tension glaucoma (HTG) and 68 normal tension glaucoma (NTG), were measured by Corvis ST to obtain intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters at baseline and at each follow-up visit after initiation of PGA treatment. The follow-up measurements were analyzed by the generalized estimate equation model with an exchangeable correlation structure. Restricted cubic spline was employed to estimate the dose-response relation between follow-up time and corneal biomechanics．Results: The mean follow-up time was 10.3 ± 7.02 months. Deformation amplitude (β=-0.0015, P=0.016), the first applanation velocity (AV1, β=-0.0004, P=0.00058) decreased and the first applanation time (AT1, β=0.0089, P<0.000001) increased statistically significantly with PGA therapy over time after adjusting for age, gender, axial length, corneal curvature, IOP and CCT. In addition, AT1 was lower (7.2950 ± 0.2707 in NTG and 7.5889 ± 0.2873 in HTG, P=0.00011) and AV1 was greater (0.1478 ± 0.0187 in NTG and 0.1314 ± 0.0191 in HTG, P=0.00002) in NTG than in HTG after adjusting for confounding factors.Conclusions: Chronic use of PGA probably influences the corneal biomechanical properties directly, which is to make cornea less deformable. Besides, corneas in NTG tended to be more deformable compared to those in HTG with long-term treatment of PGA.

scholarly journals Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Lei Tian ◽  
Yi-Fei Huang ◽  
Li-Qiang Wang ◽  
Hua Bai ◽  
Qun Wang ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Corneal Thickness ◽  
Area Under The Curve ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Biomechanical Assessment ◽  
Deformation Amplitude ◽  
Biomechanical Parameters ◽  
And Control ◽  
Corneal Biomechanical Properties

Purpose. To compare the corneal biomechanical properties of keratoconic patients and age-matched controls using corneal visualization Scheimpflug technology (Corvis ST).Methods. Sixty keratoconic eyes from 47 keratoconus patients and 60 normal eyes from 60 controls were enrolled in this prospective study. Tomography and biomechanical parameters of all eyes were obtained with the Pentacam and Corvis ST, respectively. Intraocular pressure was measured using a Goldmann applanation tonometer.Results.The tomography and biomechanical parameters of the keratoconic corneas were significantly different from those of the normal corneas except for the anterior chamber angle, first applanation length, the highest concavity time, and peak distance. The deformation amplitude was the best predictive parameter (area under the curve: 0.882), with a sensitivity of 81.7%, although there was a significant overlap between keratoconic and normal corneas that ranged from 1.0 to 1.4 mm. In both the keratoconus and control groups, the deformation amplitude was negatively correlated with intraocular pressure, central corneal thickness, and corneal volume at 3 and 5 mm.Conclusions. Corvis ST offers an alternative method for measuring corneal biomechanical properties. The possibility of classifying keratoconus based on deformation amplitude deserves clinical attention.

scholarly journals The changes of corneal biomechanical properties with long-term treatment of prostaglandin analogue measured by Corvis ST

2020 ◽  
Author(s):  
Na Wu ◽  
Yuhong Chen ◽  
Yaping Yang ◽  
Xinghuai Sun
Keyword(s):  
Open Angle Glaucoma ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Term Treatment ◽  
Prostaglandin Analogue ◽  
Corvis St ◽  
Long Term Treatment ◽  
Corneal Biomechanical Properties

Abstract Background: To investigate the corneal biomechanical changes in primary open angle glaucoma (POAG) patients treated with long-term prostaglandin analogue (PGA). Methods: 111 newly diagnosed POAG patients, including 43 high tension glaucoma (HTG) and 68 normal tension glaucoma (NTG), were measured by Corvis ST to obtain intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters at baseline and at each follow-up visit after initiation of PGA treatment. The follow-up measurements were analyzed by the generalized estimate equation model with an exchangeable correlation structure. Restricted cubic spline was employed to estimate the dose-response relation between month and corneal biomechanics． Results: The mean follow-up time was 10.3 ± 7.02 months. Deformation amplitude (DA, β=-0.0015, P =0.016), the first applanation velocity (AV1, β=-0.0004, P =0.00058) decreased and the first applanation time (AT1, β=0.0089, P <0.000001) increased statistically significantly with PGA therapy over time after adjusting for age, gender, axial length, corneal curvature, IOP and CCT. In addition, AT1 was lower (7.2950 ± 0.2707 in NTG and 7.5889 ± 0.2873 in HTG, P =0.00011) and AV1 was greater (0.1478 ± 0.0187 in NTG and 0.1314 ± 0.0191 in HTG, P =0.00002) in NTG than in HTG after adjusting for confounding factors. Conclusions: Chronic use of PGA probably could influence the corneal biomechanical properties directly, which is to make cornea less deformable. Besides, corneas in NTG tended to be more deformable compared to those in HTG with long-term treatment of PGA.

scholarly journals The changes of corneal biomechanical properties with long-term treatment of prostaglandin analogue measured by Corvis ST

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Na Wu ◽  
Yuhong Chen ◽  
Yaping Yang ◽  
Xinghuai Sun
Keyword(s):  
Open Angle Glaucoma ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Term Treatment ◽  
Prostaglandin Analogue ◽  
Corvis St ◽  
Long Term Treatment ◽  
Corneal Biomechanical Properties

Abstract Background To investigate the corneal biomechanical changes in primary open angle glaucoma (POAG) patients treated with long-term prostaglandin analogue (PGA). Methods One hundred eleven newly diagnosed POAG patients, including 43 high tension glaucoma (HTG) and 68 normal tension glaucoma (NTG), were measured by Corvis ST to obtain intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters at baseline and at each follow-up visit after initiation of PGA treatment. The follow-up measurements were analyzed by the generalized estimate equation model with an exchangeable correlation structure. Restricted cubic spline was employed to estimate the dose–response relation between follow-up time and corneal biomechanics. Results The mean follow-up time was 10.3 ± 7.02 months. Deformation amplitude (β = -0.0015, P = 0.016), the first applanation velocity (AV1, β = -0.0004, P = 0.00058) decreased and the first applanation time (AT1, β = 0.0089, P < 0.000001) increased statistically significantly with PGA therapy over time after adjusting for age, gender, axial length, corneal curvature, IOP and CCT. In addition, AT1 was lower (7.2950 ± 0.2707 in NTG and 7.5889 ± 0.2873 in HTG, P = 0.00011) and AV1 was greater (0.1478 ± 0.0187 in NTG and 0.1314 ± 0.0191 in HTG, P = 0.00002) in NTG than in HTG after adjusting for confounding factors. Conclusions Chronic use of PGA probably influences the corneal biomechanical properties directly, which is to make cornea less deformable. Besides, corneas in NTG tended to be more deformable compared to those in HTG with long-term treatment of PGA.

scholarly journals Corneal Distortion and Corneal Morphological Parameters in Naïve Eyes Analyzed with a Scheimpflug Camera

2020 ◽  
Vol 3 (2) ◽  
pp. p22
Author(s):  
Sandro Sbrodone ◽  
Adele Ragucci ◽  
Gennarfrancesco Iaccarino ◽  
Domenico de Robertis ◽  
Giovan Battista Scazzi ◽  
...  
Keyword(s):  
Refractive Surgery ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Morphological Parameters ◽  
Corvis St ◽  
Iop Measurement ◽  
Biomechanical Evaluation ◽  
Spss Software ◽  
Biomechanical Features ◽  
Linear Regressions

Background: The study of the corneal biomechanical properties (CBP) is gaining always more interest, thanks to the applications to refractive surgery and to the overall management of several corneal diseases. Purpose: To analyze the eventual relationships between corneal distortion and morphologic features in healthy subjects. Methods: one eye of one hundred and fifty-two healthy participants, 87 women and 65 men, aging from 23 to 65 years old, were evaluated in this study. Every eye underwent a complete clinical examination, that included also a tomographic scan using Pentacam HR (Oculus, Wetzlar, Germany) and a biomechanical evaluation using Corvis ST (Oculus, Wetzlar, Germany). Linear regressions among refractive defect, corneal volume (CV), anterior corneal curvature and central corneal thickness (CCT) vs corneal biomechanical features provided by Corvis ST have been ran using SPSS software version 18.0. Results: Corneal distortion factors showed a low correlation both with corneal morphological parameters and with refractive defect. No significant correlations (p> 0.01) were found among morphologic and biomechanical features evaluated. Discussion: results observed in this study could help in recognize the healthy range of values of CBP parameters provided by CST. This information could be very useful in many ophthalmology topics such as the accurate IOP measurement, the early diagnosis of corneal degenerations, such as keratoconous, and the screening of subject undergoing refractive surgery. Conclusions: even if data of this study need to be confirmed in further ones with larger populations, results here observed suggest that Corvis ST is a device providing an evaluation of corneal distortion not influenced by morphological corneal factors. This information could help in better screening and managing the diseased corneas.

scholarly journals The changes of corneal biomechanical properties with long-term treatment of prostaglandin analogue measured by Corvis ST

2020 ◽  
Author(s):  
Na Wu ◽  
Yuhong Chen ◽  
Yaping Yang ◽  
Xinghuai Sun
Keyword(s):  
Open Angle Glaucoma ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Term Treatment ◽  
Prostaglandin Analogue ◽  
Corvis St ◽  
Long Term Treatment ◽  
Corneal Biomechanical Properties

Abstract Background: To investigate the corneal biomechanical changes in primary open angle glaucoma (POAG) patients treated with long-term prostaglandin analogue (PGA). Methods: 111 newly diagnosed POAG patients, including 43 high tension glaucoma (HTG) and 68 normal tension glaucoma (NTG), were measured by Corvis ST to obtain intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters at baseline and at each follow-up visit after initiation of PGA treatment. The follow-up measurements were analyzed by the generalized estimate equation model with an exchangeable correlation structure. Restricted cubic spline was employed to estimate the dose-response relation between follow-up time and corneal biomechanics． Results: The mean follow-up time was 10.3 ± 7.02 months. Deformation amplitude (DA, β=-0.0015, P =0.016), the first applanation velocity (AV1, β=-0.0004, P =0.00058) decreased and the first applanation time (AT1, β=0.0089, P <0.000001) increased statistically significantly with PGA therapy over time after adjusting for age, gender, axial length, corneal curvature, IOP and CCT. In addition, AT1 was lower (7.2950 ± 0.2707 in NTG and 7.5889 ± 0.2873 in HTG, P =0.00011) and AV1 was greater (0.1478 ± 0.0187 in NTG and 0.1314 ± 0.0191 in HTG, P =0.00002) in NTG than in HTG after adjusting for confounding factors. Conclusions: Chronic use of PGA probably could influence the corneal biomechanical properties directly, which is to make cornea less deformable. Besides, corneas in NTG tended to be more deformable compared to those in HTG with long-term treatment of PGA.

Laser vision correction technologies: from simple to complex

The Eye ◽  
2020 ◽  
Vol 22 (129) ◽  
pp. 48-50
Author(s):  
Tatiana Shilova
Keyword(s):  
Side Effects ◽  
Refractive Surgery ◽  
Contact Lenses ◽  
Common Method ◽  
Corneal Curvature ◽  
Power Laser ◽  
Scientific Publications ◽  
Vision Correction ◽  
Laser Vision ◽  
Laser Refractive Surgery

Laser vision correction is a simple and safe way to improve vision in cases of myopia, hyperopia and astigmatism. We analyzed differences of the existing laser vision correction technologies, their risks and side effects. The main objective of laser vision correction is to change corneal curvature in order to change its refractive power. Laser refractive surgery is the most common method of eliminating the need for glasses or contact lenses. The presented data was obtained from the analysis of scientific publications and by practical means.

Influence of corneal biomechanical properties on IOP indices in patients with keratoconus

The Eye ◽  
2019 ◽  
Vol 21 (128) ◽  
pp. 15-19
Author(s):  
Irina Bubnova ◽  
Veronica Averich ◽  
Elena Belousova
Keyword(s):  
Disease Progression ◽  
Corneal Thickness ◽  
Central Zone ◽  
Biomechanical Properties ◽  
Resistance Factor ◽  
Corneal Resistance Factor ◽  
Mean Values ◽  
Coefficient Of Elasticity ◽  
D Values ◽  
Corneal Biomechanical Properties

Purpose: Evaluation of corneal biomechanical prop¬erties and their influence on IOP indices in patients with keratoconus. Material and methods. The study included 194 eyes with keratoconus (113 patients aged from 23 to 36 years old). Corneal refraction in central zone varied from 48.25 to 56.75 D, values of corneal thickness ranged from 279 to 558 μm. Patients were divided into 4 groups according to Amsler classification: I stage – 40 eyes; II stage – 78 eyes; III stage – 54 eyes and IV stage – 22 eyes. Standard ophthal¬mological examination was carried out including pneumo¬tonometry. IOP indices and values of biomechanical prop¬erties were evaluated by dynamic bidirectional pneumatic applanation and pneumatic impression. Results. Study of corneal biomechanical properties in patients with keratoconus showed a decrease of such biomechanical indices as corneal hysteresis (CH) on aver¬age to 8.42±1.12 mm Hg, corneal resistance factor (CRF) – to 7.45±0.96 mm Hg, coefficient of elasticity (CE) – 5.35± 0.87 mm Hg. Values of these indices strongly depended on the stage of keratoconus. In the whole sample, the aver¬age corneal compensated IOP (IOPcc) amounted to 15.08± 2.43 mm Hg, Goldman IOP (IOPg) was 11.61±2.37 mm Hg and pneumatic tonometry IOP (IOPp) was 10.13±2.94 mm Hg. IOPcc indices didn’t have any statistically significant differ¬ence in dependence on the stage of keratoconus (р>0.473), while in process of disease progression IOPg and IOPp indi¬ces showed statistically significant decrease of mean values. Conclusion. Progression of keratoconus led to a de¬crease in corneal biomechanical properties which deter¬mine reduction of such indices as IOPg and IOPp in contrast to IOPcc.

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