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Corneal Hysteresis

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https://www.readbyqxmd.com/read/28210179/corneal-biomechanics-in-normal-saudi-individuals
#1
Khalid Al-Arfaj, Sanaa A Yassin, Walaa Al-Dairi, Fatimah Al-Shamlan, Mohanna Al-Jindan
PURPOSE: The aim of this study was to determine and relate corneal biomechanical metrics with demographic, tomographic and refractive data in healthy Saudi people. DESIGN: Prospective, cross-sectional, observational study. PARTICIPANTS: The study included 215 normal Saudi adult individuals. METHODS: Corneal hysteresis (CH) and corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were measured by ocular response analyzer...
July 2016: Saudi Journal of Ophthalmology: Official Journal of the Saudi Ophthalmological Society
https://www.readbyqxmd.com/read/28192588/conventional-versus-inverted-side-cut-flaps-for-femtosecond-laser-assisted-lasik-laboratory-and-clinical-evaluation
#2
Vishal Jhanji, Tommy C Y Chan, Wai Ying Li, Rayne R Lim, Marco C Y Yu, Kasin Law, Peng Yi, Yolanda W Y Yip, Yumeng Wang, Tsz Kin Ng, Shyam S Chaurasia, Rajiv R Mohan
PURPOSE: To study the differences in early corneal cellular events and biomechanical properties after femtosecond laser-assisted LASIK performed using conventional or inverted side-cut angles. METHODS: In the laboratory study, left eyes of 24 rabbits underwent LASIK flap creation with a 70° or 115° side-cut. The contralateral eyes served as controls. The corneas were harvested 24 hours postoperatively. In the clinical study, 2 eyes of each patient (n = 29) were randomized to corneal flap creation with 70° or 115° side-cut angles during LASIK...
February 1, 2017: Journal of Refractive Surgery
https://www.readbyqxmd.com/read/28168049/photorefractive-keratectomy-for-residual-myopia-after-myopic-laser-in-situ-keratomileusis
#3
Kamal A M Solaiman, Sameh M Fouda, Ashraf Bor'i, Haitham Y Al-Nashar
Purpose. To evaluate the safety, efficacy, and predictability of photorefractive keratectomy (PRK) on the corneal flap for correction of residual myopia following myopic laser in situ keratomileusis (LASIK). Patients and Methods. A retrospective study on eyes retreated by PRK on the corneal flap for residual myopia after LASIK. All eyes had no enough stroma after LASIK sufficient for LASIK enhancement. Data included spherical equivalent (SE), uncorrected and best corrected visual acuity (UCVA and BCVA), central pachymetry, corneal higher order aberrations (HOAs), corneal hysteresis (CH), corneal resistance factor (CRF), and corneal haze...
2017: Journal of Ophthalmology
https://www.readbyqxmd.com/read/28163860/refinement-of-intraocular-pressure-measurements-made-by-ocular-response-analyzer-following-laser-in-situ-keratomileusis-using-m2-90-moria-microkeratome-for-egyptian-myopic-and-astigmatic-patients
#4
Tamer Adel Refai, Olfat A Hassanin
INTRODUCTION: The Goldmann applanation tonometer readings were noted to be markedly reduced after Lasik surgery using a thin flap technique which is widely used nowadays, to correct a wide range of myopia and astigmatism. The Ocular Response Analyzer (ORA) is considered one of the important tools for refinement of Intraocular Pressure (IOP) measurements. The aim of this study is to evaluate and refine ORA measurements for IOP changes post- M2 90 Moria microkeratome Lasik procedure for Egyptian myopic and astigmatic patients trying to aid in glaucoma diagnosis and management...
December 2016: Electronic Physician
https://www.readbyqxmd.com/read/28162196/-comparison-of-the-effects-of-different-side-cut-angles-on-corneal-biomechanical-properties-after-femtosecond-laser-assisted-laser-in-situ-keratomileusis
#5
H Li, Y Wang, R Dou, L Wang, L L Xu, X J Li, J M Zhang
Objective: To evaluate the effects of side-cut angles on corneal biomechanical properties after femtosecond laser assisted-laser in situ keratomileusis (FS-LASIK). Methods: In this clinical control study, 97 right eyes of 97 patients with myopia and myopic astigmatism undergoing FS-LASIK surgery were included randomly. Two types of side-cut angles were designed for the flap, 90° in 48 eyes and 130° in 49 eyes. The values of corneal resistance factor (CRF), cornea hysteresis (CH) and 37 biomechanical waveform parameters were measured using the ocular response analyzer preoperatively and at 1 and 3 months postoperatively...
January 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28162194/-analysis-on-corneal-deformation-and-corneal-biomechanical-changes-after-small-incision-lenticule-extraction
#6
Y L Huang, Y Wang, R Dou, S B Jin, L J Liu, H Li, P H Wei
Objective: To investigate biomechanical effects of central corneal thickness (CCT), and to explore the possible safe range for the tissue removal and percentage of tissue ablation (PTA) of small incision lenticule extraction (SMILE). Methods: Clinical observational study. One hundred and eighty-seven cases (365 eyes) undergoing SMILE surgery were enrolled. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured before and after surgery by the ocular response analyzer (ORA). Linear regression of CH, CRF and CCT, and percentage of tissue ablation were calculated...
January 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28149787/small-incision-lenticule-extraction-versus-femtosecond-lenticule-extraction-for-myopic-a-systematic-review-and-meta-analysis
#7
Jia-Song Wang, Hua-Tao Xie, Ye Jia, Ming-Chang Zhang
AIM: To examine differences in efficacy, accuracy, safety, aberrations and corneal biomechanical between Small incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx) for myopia. METHODS: Comprehensive studies were conducted on the PubMed, MEDLINE, EMBASE, and Cochrane Controlled Trials Register before 31 July, 2015. Meta-analyses were performed on the primary outcomes [loss of ≥2 lines of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) ≥20/20, spherical equivalent (SE) within ±0...
2017: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/28139064/corneal-profile-in-primary-congenital-glaucoma
#8
Azadeh Doozandeh, Shahin Yazdani, Shabnam Ansari, Mohammad Pakravan, Tahmineh Motevasseli, Bagher Hosseini, Mehdi Yasseri
PURPOSE: To investigate biomechanical and ultrastructural corneal parameters and ocular biometrics in the affected eyes of patients with unilateral primary congenital glaucoma (PCG) as compared to unaffected fellow eyes and age-matched healthy controls. METHODS: A total of 12 patients with treated unilateral PCG and 10 normal subjects were evaluated. LENSTAR was performed to determine biometric parameters; the ocular response analyser was employed to determine biomechanical properties and slit-scanning confocal microscopy was used for evaluation of corneal ultrastucture...
January 31, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28107088/the-national-eye-survey-of-trinidad-and-tobago-nestt-rationale-objectives-and-methodology
#9
Tasanee Braithwaite, Neville Q Verlander, Debra Bartholomew, Petra Bridgemohan, Kevin McNally, Allana Roach, Subash Sharma, Deo Singh, Konrad Pesudovs, Surujpal Teelucksingh, Christine Carrington, Samuel Ramsewak, Rupert Bourne
PURPOSE: This paper describes the rationale, study design and procedures of the National Eye Survey of Trinidad and Tobago (NESTT). The main objective of this survey is to obtain prevalence estimates of vision impairment and blindness for planning and policy development. METHODS: A population-based, cross-sectional survey was undertaken using random multistage cluster sampling, with probability-proportionate-to-size methods. Eligible participants aged 5 years and older were sampled from the non-institutional population in each of 120 cluster segments...
January 20, 2017: Ophthalmic Epidemiology
https://www.readbyqxmd.com/read/28094315/the-usefulness-of-corvisst-tonometry-and-the-ocular-response-analyzer-to-assess-the-progression-of-glaucoma
#10
Masato Matsuura, Kazunori Hirasawa, Hiroshi Murata, Shunsuke Nakakura, Yoshiaki Kiuchi, Ryo Asaoka
Corneal Visualization Scheimpflug Technology (CST) and Ocular Response Analyzer (ORA) measurements were carried out in 105 eyes of 69 patients with primary open-angle glaucoma. All patients had axial length (AL), central corneal thickness (CCT), intraocular pressure (IOP) with Goldmann applanation tonometry (GAT) and eight visual fields (VF)s with the Humphrey Field Analyzer. VF progression was summarized using a time trend analysis of mean total deviation (mTD) and the association between mTD progression rate and a number of ocular parameters (including CST and ORA measurements) was assessed using mixed linear regression analysis...
January 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28081172/influence-of-corneal-opacity-on-intraocular-pressure-assessment-in-patients-with-lysosomal-storage-diseases
#11
Joanna Wasielica-Poslednik, Giuseppe Politino, Irene Schmidtmann, Katrin Lorenz, Katharina Bell, Norbert Pfeiffer, Susanne Pitz
AIMS: To investigate an influence of mucopolysaccharidosis (MPS)- and Morbus Fabry-associated corneal opacities on intraocular pressure (IOP) measurements and to evaluate the concordance of the different tonometry methods. METHODS: 25 MPS patients with or without corneal clouding, 25 Fabry patients with cornea verticillata ≥ grade 2 and 25 healthy age matched controls were prospectively included into this study. Outcome measures: Goldmann applanation tonometry (GAT); palpatory assessment of IOP; Goldmann-correlated intraocular pressure (IOPg), corneal-compensated intraocular pressure (IOPcc), corneal resistance factor (CRF) and corneal hysteresis (CH) assessed by Ocular Response Analyzer (ORA); central corneal thickness (CCT) and density assessed with Pentacam...
2017: PloS One
https://www.readbyqxmd.com/read/28076565/effect-of-corneal-biomechanical-properties-on-surgically-induced-astigmatism-and-higher-order-aberrations-after-cataract-surgery
#12
Mustafa Koç, Çağrı İlhan, Yaran Koban, Kemal Özülken, İrfan Durukan, Pelin Yılmazbaş
Purpose: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. Methods: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR)...
November 2016: Arquivos Brasileiros de Oftalmologia
https://www.readbyqxmd.com/read/28068950/corneal-hysteresis-in-patients-with-glaucoma-like-optic-discs-ocular-hypertension-and-glaucoma
#13
Melissa L Murphy, Olya Pokrovskaya, Marie Galligan, Colm O'Brien
BACKGROUND: To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. METHODS: In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination...
January 10, 2017: BMC Ophthalmology
https://www.readbyqxmd.com/read/28068365/tonographic-effect-of-ocular-response-analyzer-in-comparison-to-goldmann-applanation-tonometry
#14
Martin Zimmermann, Susanne Pitz, Irene Schmidtmann, Norbert Pfeiffer, Joanna Wasielica-Poslednik
AIMS: The tonographic effect is a phenomenon of intraocular pressure (IOP) reduction following repeated tonometry. This study examines whether the tonographic effect occurs following IOP measurement performed with Ocular Response Analyzer (ORA). METHODS: Both eyes of 31 glaucoma patients and 35 healthy controls underwent nine IOP-measurements performed with GAT and ORA. The number of GAT and ORA measurements performed on each eye differed depending on the randomly allocated investigation scheme...
2017: PloS One
https://www.readbyqxmd.com/read/28035498/accelerated-versus-conventional-corneal-collagen-cross-linking-in-patients-with-keratoconus-an-intrapatient-comparative-study
#15
Mohammad Mehdi Sadoughi, Bahram Einollahi, Alireza Baradaran-Rafii, Danial Roshandel, Hamidreza Hasani, Mehrdad Nazeri
PURPOSE: To compare the outcomes of the conventional and accelerated corneal collagen cross-linking (CXL) in patients with bilateral progressive keratoconus (KC). METHODS: Fifteen consecutive patients with bilateral progressive KC were enrolled. In each patient, the fellow eyes were randomly assigned to the conventional CXL (3 mW/cm(2) for 30 min) or accelerated CXL (ACXL) (9 mW/cm(2) for 10 min) groups. Manifest refraction; uncorrected and corrected distant visual acuity; maximum and mean keratometry; corneal hysteresis and corneal resistance factor; endothelial cell density and morphology; central corneal thickness; and wavefront aberrations were measured before and 12 months after the CXL...
December 29, 2016: International Ophthalmology
https://www.readbyqxmd.com/read/28002108/corneal-biomechanical-properties-after-penetrating-keratoplasty-or-deep-anterior-lamellar-keratoplasty-using-the-ocular-response-analyzer-a-meta-analysis
#16
Min-Shan Jiang, Jing-Yuan Zhu, Xue Li, Nan-Nan Zhang, Xue-Dian Zhang
PURPOSE: To evaluate the corneal biomechanical properties of patients who have undergone penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) using the ocular response analyzer. METHODS: Stata 13.0 SE was used for this meta-analysis. Studies in the literature that focused on corneal hysteresis (CH) or corneal resistance factor (CRF) after PK or DALK were retrieved by searching PubMed, Embase, Ovid, and Cochrane databases. We present the results as weighted mean difference (WMD) with a corresponding 95% confidence interval (CI)...
March 2017: Cornea
https://www.readbyqxmd.com/read/27977478/corneal-biomechanical-changes-after-trabeculectomy-and-the-impact-on-intraocular-pressure-measurement
#17
Karin R Pillunat, Eberhard Spoerl, Naim Terai, Lutz E Pillunat
PURPOSE: To evaluate corneal biomechanical changes induced by trabeculectomy and their impact on intraocular pressure (IOP) measurements. MATERIALS AND METHODS: In total, 35 eyes of 35 consecutive glaucoma patients undergoing first-time trabeculectomy with mitomycin C were enrolled in this prospective interventional case series. Goldmann applanation tonometry (GAT) IOP, central corneal thickness, axial length, and Ocular Response Analyzer measurements [Goldmann-correlated IOP (IOPg), corneal-compensated IOP (IOPcc), corneal hysteresis (CH), and corneal resistance factor (CRF)] were assessed before and 6 months after uncomplicated trabeculectomy...
December 13, 2016: Journal of Glaucoma
https://www.readbyqxmd.com/read/27893094/comparison-of-patient-specific-computational-modeling-predictions-and-clinical-outcomes-of-lasik-for-myopia
#18
Ibrahim Seven, Ali Vahdati, Vinicius Silbiger De Stefano, Ronald R Krueger, William J Dupps
Purpose: To assess the predictive accuracy of simulation-based LASIK outcomes. Methods: Preoperative and 3-month post-LASIK tomographic data from 20 eyes of 12 patients who underwent wavefront-optimized LASIK for myopia were obtained retrospectively. Patient-specific finite element models were created and case-specific treatment settings were simulated. Simulated keratometry (SimK) values and the mean tangential curvature of the central 3 mm (Kmean) were obtained from the anterior surfaces of the clinical tomographies, and computational models were compared...
November 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27873338/high-myopes-have-lower-normalised-corneal-tangent-moduli-less-stiff-corneas-than-low-myopes
#19
Ying Hon, Guo-Zhen Chen, Shu-Hao Lu, David C C Lam, Andrew K C Lam
PURPOSE: To compare corneal tangent moduli between low and high myopes. METHODS: Corneal hysteresis (CH) and corneal resistance factor (CRF) of 32 low and 32 high myopes were obtained using an Ocular Response Analyzer, followed by a corneal indentation device that measured corneal stiffness. Corneal topography, pachymetry, Goldmann applanation tonometry intraocular pressure (GAT-IOP), and corneal compensated intraocular pressure (IOPcc) were also obtained. Corneal tangent modulus was calculated on the basis of corneal stiffness, central corneal thickness and corneal radius...
January 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/27847644/relationship-among-corneal-biomechanics-anterior-segment-parameters-and-geometric-corneal-parameters
#20
Sadık Görkem Çevik, Sertaç Argun Kıvanç, Berna Akova-Budak, Mediha Tok-Çevik
Purpose. To investigate the relationship between corneal biomechanical parameters, anterior segment parameters, and geometric corneal parameters in a healthy Caucasian group. Methods. This retrospective study included the healthy eyes with best corrected visual acuity of at least 20/40 of 122 Caucasian subjects. The anterior segment parameters and geometric corneal parameters such as corneal volume, central corneal thickness, horizontal and vertical corneal radii, anterior and posterior steep, and flat keratometric values were measured with a Scheimpflug camera...
2016: Journal of Ophthalmology
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