Long-term Evaluation of Corneal Biomechanical Properties After Corneal Cross-linking for Keratoconus: A 4-Year Longitudinal Study

2018 ◽  
Vol 34 (12) ◽  
pp. 849-856 ◽  
Author(s):  
Mohammad-Reza Sedaghat ◽  
Hamed Momeni-Moghaddam ◽  
Renato Ambrósio ◽  
Cynthia J. Roberts ◽  
Abbas-Ali Yekta ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Biomechanical Properties ◽  
Cross Linking ◽  
Term Evaluation ◽  
Corneal Biomechanical Properties

Impact of oral contraceptive use and menstrual phases on patellar tendon morphology, biochemical composition, and biomechanical properties in female athletes

2013 ◽  
Vol 114 (8) ◽  
pp. 998-1008 ◽  
Author(s):  
Mette Hansen ◽  
Christian Couppe ◽  
Christina S. E. Hansen ◽  
Dorthe Skovgaard ◽  
Vuokko Kovanen ◽  
...  
Keyword(s):  
Patellar Tendon ◽  
Female Athletes ◽  
Maximum Voluntary Contraction ◽  
Biomechanical Properties ◽  
Cross Sectional Area ◽  
Cross Linking ◽  
Sectional Area ◽  
Cross Sectional ◽  
Collagen Cross Linking

Sex differences exist with regards to ligament and tendon injuries. Lower collagen synthesis has been observed in exercising women vs. men, and in users of oral contraceptives (OC) vs. nonusers, but it is unknown if OC will influence tendon biomechanics of women undergoing regular training. Thirty female athletes (handball players, 18–30 yr) were recruited: 15 long-term users of OC (7.0 ± 0.6 yr) and 15 nonusers (>5 yr). Synchronized values of patellar tendon elongation (obtained by ultrasonography) and tendon force were sampled during ramped isometric knee extensor maximum voluntary contraction to estimate mechanical tendon properties. Furthermore, tendon cross-sectional area and length were measured from MRI images, and tendon biopsies were obtained for analysis of tendon fibril characteristics and collagen cross-linking. Overall, no difference in tendon biomechanical properties, tendon fibril characteristics, or collagen cross-linking was observed between the OC users and nonusers, or between the different phases of the menstrual cycle. In athletes, tendon cross-sectional area in the preferred jumping leg tended to be larger than that in the contralateral leg ( P = 0.09), and a greater absolute ( P = 0.01) and normalized tendon stiffness ( P = 0.02), as well as a lower strain ( P = 0.04), were observed in the jumping leg compared with the contralateral leg. The results indicate that long-term OC use or menstrual phases does not influence structure or mechanical properties of the patellar tendon in female team handball athletes.

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 Spatial characterization of corneal biomechanical properties with optical coherence elastography after UV cross-linking

2014 ◽  
Vol 5 (5) ◽  
pp. 1419 ◽  
Author(s):  
Michael D. Twa ◽  
Jiasong Li ◽  
Srilatha Vantipalli ◽  
Manmohan Singh ◽  
Salavat Aglyamov ◽  
...  
Keyword(s):  
Biomechanical Properties ◽  
Cross Linking ◽  
Optical Coherence ◽  
Spatial Characterization ◽  
Corneal Biomechanical Properties

Prospective one year study of corneal biomechanical changes following high intensity, accelerated cornea cross-linking in patients with keratoconus using a non-contact tonometer

2021 ◽  
pp. 112067212110697
Author(s):  
Mohammed Ziaei ◽  
Jinny J Yoon ◽  
Hans R Vellara ◽  
Akilesh Gokul ◽  
Jay J Meyer ◽  
...  
Keyword(s):  
High Intensity ◽  
High Speed ◽  
Biomechanical Properties ◽  
High Irradiance ◽  
Cross Linking ◽  
Continuous Exposure ◽  
Tertiary Referral Center ◽  
Significant Difference ◽  
Prospective Longitudinal ◽  
Corneal Biomechanical Properties

Purpose To characterize corneal biomechanical properties utilizing a dynamic ultra-high-speed Scheimpflug camera equipped with a non-contact tonometer (CorVis ST, CST) in keratoconic corneas following continuous high intensity, high irradiance corneal cross-linking. Design Prospective longitudinal single-centre study at a tertiary referral center. Methods Corneal biomechanical properties were measured in patients with progressive keratoconus undergoing high intensity (30 mW/cm2), high irradiance (5.4 J/cm2), accelerated corneal cross-linking with continuous exposure to ultraviolet-A for 4 min. CST was used to assess corneal biomechanical properties pre-operatively and at 1, 3, 6 and 12 months post-operatively. CST output videos were further analyzed using several previously reported algorithms. Results A total of 25 eyes of 25 participants were examined. The mean age of participants was 20.9 ± 5.3 years; 56% were male and 80% were of Māori or Pacific Island origin. Energy absorbed area (mN mm), was the only significantly changed parameter compared to baseline at all time points measuring 3.61 ± 1.19 preoperatively, 2.81 ± 1.15 at 1 month ( p = 0.037), 2.79 ± 0.81 ( p = 0.033) at 3 months, 2.76 ± 0.95 ( p = 0.028) at 6 months and 2.71 ± 1.18 ( p = 0.016) at 12 months. Conclusions The significant difference between the pre and post-operative energy absorbed area appears to reflect changes in corneal viscous properties that occur following corneal cross-linking.

scholarly journals Corneal Biomechanical Properties at Different Corneal Cross-Linking (CXL) Irradiances

2014 ◽  
Vol 55 (5) ◽  
pp. 2881 ◽  
Author(s):  
Arthur Hammer ◽  
Olivier Richoz ◽  
Samuel Arba Mosquera ◽  
David Tabibian ◽  
Florence Hoogewoud ◽  
...  
Keyword(s):  
Biomechanical Properties ◽  
Cross Linking ◽  
Corneal Biomechanical Properties

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.

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