The Experts below are selected from a list of 2085 Experts worldwide ranked by ideXlab platform
Vishal Jhanji - One of the best experts on this subject based on the ideXlab platform.
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comparison of corneal measurements in keratoconus using swept source optical coherence tomography and combined placido Scheimpflug Imaging
Acta Ophthalmologica, 2017Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:Purpose The aim of this study was to provide a comprehensive comparison of reliability of corneal topographic measurements in keratoconic eyes using swept-source optical coherence tomography (OCT) and a combined Placido–Scheimpflug Imaging. Methods A total of 30 eyes of 30 patients were included. The mean age was 31.2 ± 8.4 years. Two consecutive topographic measurements were obtained for one eye of each patient using swept-source OCT (CASIA) and combined Placido–Scheimpflug Imaging (TMS-5). Test–retest reliability of CASIA and TMS-5 measurements including central corneal thickness (CCT) and thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, average keratometry (Avg K), cylinder, and, best-fit spheres (BFS) of the anterior and posterior corneal surfaces were evaluated. Results There was no systematic or scaling bias in any parameter in both devices. Systematic differences between CASIA and TMS-5 were found in posterior corneal Kf, Avg K and BFS, CCT and TCT (p ≤ 0.002); scaling differences between CASIA and TMS-5 were also found in CCT and TCT (p ≤ 0.002). Both machines illustrated adequate reliability. Intraclass correlation coefficients (ICC) ≥0.952 was recorded for all parameters measured with CASIA and ICC ≥ 0.914 was recorded for all parameters on TMS-5. CASIA showed significantly higher ICCs in CCT and TCT, and posterior corneal BFS (p < 0.001). Conclusions This study showed significant differences in posterior corneal surface and corneal thickness measurements between swept-source OCT and combined Placido–Scheimpflug Imaging in eyes with keratoconus. Swept-source OCT might be preferred over Placido–Scheimpflug Imaging owing to better repeatability of measurements.
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Comparison of corneal measurements in keratoconus using swept‐source optical coherence tomography and combined Placido–Scheimpflug Imaging
Acta Ophthalmologica, 2016Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:Purpose The aim of this study was to provide a comprehensive comparison of reliability of corneal topographic measurements in keratoconic eyes using swept-source optical coherence tomography (OCT) and a combined Placido–Scheimpflug Imaging. Methods A total of 30 eyes of 30 patients were included. The mean age was 31.2 ± 8.4 years. Two consecutive topographic measurements were obtained for one eye of each patient using swept-source OCT (CASIA) and combined Placido–Scheimpflug Imaging (TMS-5). Test–retest reliability of CASIA and TMS-5 measurements including central corneal thickness (CCT) and thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, average keratometry (Avg K), cylinder, and, best-fit spheres (BFS) of the anterior and posterior corneal surfaces were evaluated. Results There was no systematic or scaling bias in any parameter in both devices. Systematic differences between CASIA and TMS-5 were found in posterior corneal Kf, Avg K and BFS, CCT and TCT (p ≤ 0.002); scaling differences between CASIA and TMS-5 were also found in CCT and TCT (p ≤ 0.002). Both machines illustrated adequate reliability. Intraclass correlation coefficients (ICC) ≥0.952 was recorded for all parameters measured with CASIA and ICC ≥ 0.914 was recorded for all parameters on TMS-5. CASIA showed significantly higher ICCs in CCT and TCT, and posterior corneal BFS (p
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Longitudinal Evaluation of Cornea With Swept-Source Optical Coherence Tomography and Scheimpflug Imaging Before and After Lasik
Medicine, 2015Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:AbstractSwept-source optical coherence tomography (OCT) is the latest advancement in anterior segment Imaging. There are limited data regarding its performance after laser in situ keratomileusis (LASIK). We compared the reliability of swept-source OCT and Scheimpflug Imaging for evaluation of cornea
S P S Grewal - One of the best experts on this subject based on the ideXlab platform.
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comparison of Scheimpflug Imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles
Eye, 2011Co-Authors: Dilraj S. Grewal, Gagandeep S Brar, Rakesh K Jain, S P S GrewalAbstract:Comparison of Scheimpflug Imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles
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Comparison of Scheimpflug Imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles
Eye, 2011Co-Authors: D S Grewal, G S Brar, R Jain, S P S GrewalAbstract:Purpose To compare the performance of anterior chamber volume (ACV) and anterior chamber depth (ACD) obtained using Scheimpflug Imaging with angle opening distance (AOD500) and trabecular-iris space area (TISA500) obtained using spectral domain anterior segment optical coherence tomography (SD-ASOCT) in detecting narrow angles classified using gonioscopy. Methods In this prospective, cross-sectional observational study, 265 eyes of 265 consecutive patients underwent sequential Scheimpflug Imaging, SD-ASOCT Imaging, and gonioscopy. Correlations between gonioscopy grading, ACV, ACD, AOD500, and TISA500 were evaluated. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and likelihood ratios (LRs) were calculated to assess the performance of ACV, ACD, AOD500, and TISA500 in detecting narrow angles (defined as Shaffer grade ≤1 in all quadrants). SD-ASOCT images were obtained at the nasal and temporal quadrants only. Results Twenty-eight eyes (10.6%) were classified as narrow angles on gonioscopy. ACV correlated with gonioscopy grading ( P
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Posterior capsule rupture following closed globe injury: Scheimpflug Imaging, pathogenesis, and management
European Journal of Ophthalmology, 2008Co-Authors: Dilraj S. Grewal, Gagandeep S Brar, Rakesh K Jain, S P S GrewalAbstract:PURPOSE. To report the Scheimpflug and clinical findings in a case of pediatric posterior capsule rupture due to blunt ocular trauma. METHODS. Interventional case report. Analysis of Scheimpflug findings and review of literature. RESULTS. An 11-year-old boy presented 2 days after blunt trauma to the left eye with a slingshot. On examination his best-corrected visual acuity (BCVA) was 20/20 in the right eye and 20/400 in the left. Slitlamp examination (left eye) revealed a Vossius ring, traumatic cataract, and traumatic posterior capsular rupture (TPCR).The contour of the posterior bulge corresponded to the edges of the TPCR. Scheimpflug Imaging (Pentacam 70700: Oculus, Wetzlar, Germany) confirmed traumatic cataract in region of TPCR evidenced by increased lens density at cortex-vitreous interface, absence of vitreous prolapse into the anterior chamber, and the amount of residual nucleus. The extent of the TPCR in the greatest and least dimensions was documented before and after intraocular lens (IOL) implantation. Intraoperatively, TPCR was evident and phacoemulsification with IOL implant was performed. Postoperatively, his BCVA improved to 20/20 in the left eye with a well-centered in-thebag IOL as found on slit lamp and Scheimpflug images. C ONCLUSIONS. This report highlights the use of Scheimpflug Imaging in isolated posterior capsule rupture following closed globe injury, to visualize and quantify the size of posterior capsule rupture and its role in management. (Eur J Ophthalmol 2008; 18: 453-5)
Dilraj S. Grewal - One of the best experts on this subject based on the ideXlab platform.
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Clinical applications of Scheimpflug Imaging in cataract surgery
Saudi Journal of Ophthalmology, 2011Co-Authors: Dilraj S. Grewal, Satinder Pal Singh GrewalAbstract:Since the Scheimpflug principle was first described over a century ago, there has been a great interest among ophthalmologists for the use of Scheimpflug camera in anterior segment Imaging. Scheimpflug Imaging has since advanced significantly and modern day instruments provide comprehensive Imaging and topographic data of the anterior segment. In this article the clinical applications and limitations of Scheimpflug Imaging in modern cataract surgery patients are discussed. This article reviews recent work on assessment of lens transparency for cataract grading and integrity, using preoperative lens density measurements to help predict phacoemulsification parameters, its utility in challenging situations like capsular bag distension syndrome and traumatic cataract and assessment of density of the posterior capsule for objectively quantifying posterior-capsule opacification.
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comparison of Scheimpflug Imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles
Eye, 2011Co-Authors: Dilraj S. Grewal, Gagandeep S Brar, Rakesh K Jain, S P S GrewalAbstract:Comparison of Scheimpflug Imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles
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Assessment of central corneal thickness in normal, keratoconus, and post-laser in situ keratomileusis eyes using Scheimpflug Imaging, spectral domain optical coherence tomography, and ultrasound pachymetry.
Journal of Cataract and Refractive Surgery, 2010Co-Authors: Dilraj S. Grewal, Gagandeep S Brar, Satinder Pal Singh GrewalAbstract:Purpose To compare the central corneal thickness (CCT) in normal eyes, eyes with keratoconus, and eyes after laser in situ keratomileusis (LASIK) using 3 methods. Setting Cornea Clinic, Grewal Eye Institute, Chandigarh, India. Methods In this study, CCT was measured by sequential Scheimpflug Imaging, spectral-domain anterior segment optical coherence tomography (AS-OCT), and ultrasound (US) pachymetry. Results Each of the 3 groups comprised 50 eyes. There were no differences between the 3 groups in age, sex, or intraocular pressure. In normal eyes, CCT was statistically significantly higher by US pachymetry (mean 525.8 μm ± 41.4) [SD] than by Scheimpflug Imaging (mean 519.4 ± 40.9 μm) and AS-OCT (mean 517.9 ± 41.5 μm) (both P P = .002) and AS-OCT (mean 441.8 ± 58.4 μm) ( P = .007). In post-LASIK eyes CCT by US pachymetry (mean 462.4 ± 44.7 μm) was significantly higher than by Scheimpflug Imaging (mean 457.9 ± 33.6 μm) ( P = .012) and AS-OCT (mean 455.4 ± 43.2 μm) ( P Conclusions There was a statistically significant difference between Scheimpflug Imaging and US pachymetry and AS-OCT, with US pachymetry measurements being consistently thicker. Thus, CCT should be interpreted in the context of the instrument used. Financial disclosure No author has a financial or proprietary interest in any material or method mentioned.
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Clinical applications of Scheimpflug Imaging
Expert Review of Ophthalmology, 2009Co-Authors: Dilraj S. Grewal, Satinder Pal Singh GrewalAbstract:Since the Scheimpflug principle was first described more than a century ago, there has been great interest among ophthalmologists in the use of Scheimpflug cameras in anterior-segment Imaging. Scheimpflug cameras have advanced significantly and modern-day instruments provide comprehensive Imaging and topographic data of the anterior segment. The clinical applications and limitations of Scheimpflug Imaging in corneal, cataract and refractive surgery patients are discussed. This article also covers an assessment of anterior chamber biometry for precataract surgery calculations and glaucoma screening, corneal topography of the anterior and posterior corneal surfaces using elevation data for early detection of keratoconus and post-laser in situ keratomileusis ectasia, lens changes with accommodation, lens transparency for cataract grading, and integrity and density of the posterior capsule for posterior-capsule opacification grading using the currently commercially available Scheimpflug cameras.
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Scheimpflug Imaging of pediatric posterior capsule rupture.
Indian Journal of Ophthalmology, 2009Co-Authors: Dilraj S. Grewal, Rajeev Jain, Gagandeep S Brar, Satinder Pal Singh GrewalAbstract:We report a case of an 11-year-old boy who presented two days after blunt trauma to the left eye with a slingshot. On examination his best corrected visual acuity (BCVA) was 20/20 in the right eye and 20/400 in the left eye. Slit-lamp examination of the left eye revealed a Vossius ring, traumatic cataract, traumatic posterior capsule tear (PCT). The contour of the posterior capsule bulge corresponded to the edges of the PCT. Rotating Scheimpflug Imaging (Pentacam 70700:Oculus, Wetzlar Germany) confirmed the traumatic cataract in the region of the PCT visualized as increased lens density at the cortex-vitreous interface. The extent of the PCT in the greatest and least dimensions was documented before and after intraocular lens (IOL) implantation. Intra-operatively, the PCT was evident and phaco-emulsification with an IOL implant was performed. Postoperatively, his BCVA improved to 20/20 in the left eye with a well-centered in-the-bag IOL as found on slit-lamp and Scheimpflug images.
Tommy C Y Chan - One of the best experts on this subject based on the ideXlab platform.
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comparison of corneal measurements in keratoconus using swept source optical coherence tomography and combined placido Scheimpflug Imaging
Acta Ophthalmologica, 2017Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:Purpose The aim of this study was to provide a comprehensive comparison of reliability of corneal topographic measurements in keratoconic eyes using swept-source optical coherence tomography (OCT) and a combined Placido–Scheimpflug Imaging. Methods A total of 30 eyes of 30 patients were included. The mean age was 31.2 ± 8.4 years. Two consecutive topographic measurements were obtained for one eye of each patient using swept-source OCT (CASIA) and combined Placido–Scheimpflug Imaging (TMS-5). Test–retest reliability of CASIA and TMS-5 measurements including central corneal thickness (CCT) and thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, average keratometry (Avg K), cylinder, and, best-fit spheres (BFS) of the anterior and posterior corneal surfaces were evaluated. Results There was no systematic or scaling bias in any parameter in both devices. Systematic differences between CASIA and TMS-5 were found in posterior corneal Kf, Avg K and BFS, CCT and TCT (p ≤ 0.002); scaling differences between CASIA and TMS-5 were also found in CCT and TCT (p ≤ 0.002). Both machines illustrated adequate reliability. Intraclass correlation coefficients (ICC) ≥0.952 was recorded for all parameters measured with CASIA and ICC ≥ 0.914 was recorded for all parameters on TMS-5. CASIA showed significantly higher ICCs in CCT and TCT, and posterior corneal BFS (p < 0.001). Conclusions This study showed significant differences in posterior corneal surface and corneal thickness measurements between swept-source OCT and combined Placido–Scheimpflug Imaging in eyes with keratoconus. Swept-source OCT might be preferred over Placido–Scheimpflug Imaging owing to better repeatability of measurements.
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Comparison of corneal measurements in keratoconus using swept‐source optical coherence tomography and combined Placido–Scheimpflug Imaging
Acta Ophthalmologica, 2016Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:Purpose The aim of this study was to provide a comprehensive comparison of reliability of corneal topographic measurements in keratoconic eyes using swept-source optical coherence tomography (OCT) and a combined Placido–Scheimpflug Imaging. Methods A total of 30 eyes of 30 patients were included. The mean age was 31.2 ± 8.4 years. Two consecutive topographic measurements were obtained for one eye of each patient using swept-source OCT (CASIA) and combined Placido–Scheimpflug Imaging (TMS-5). Test–retest reliability of CASIA and TMS-5 measurements including central corneal thickness (CCT) and thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, average keratometry (Avg K), cylinder, and, best-fit spheres (BFS) of the anterior and posterior corneal surfaces were evaluated. Results There was no systematic or scaling bias in any parameter in both devices. Systematic differences between CASIA and TMS-5 were found in posterior corneal Kf, Avg K and BFS, CCT and TCT (p ≤ 0.002); scaling differences between CASIA and TMS-5 were also found in CCT and TCT (p ≤ 0.002). Both machines illustrated adequate reliability. Intraclass correlation coefficients (ICC) ≥0.952 was recorded for all parameters measured with CASIA and ICC ≥ 0.914 was recorded for all parameters on TMS-5. CASIA showed significantly higher ICCs in CCT and TCT, and posterior corneal BFS (p
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Longitudinal Evaluation of Cornea With Swept-Source Optical Coherence Tomography and Scheimpflug Imaging Before and After Lasik
Medicine, 2015Co-Authors: Tommy C Y Chan, Sayantan Biswas, Vishal JhanjiAbstract:AbstractSwept-source optical coherence tomography (OCT) is the latest advancement in anterior segment Imaging. There are limited data regarding its performance after laser in situ keratomileusis (LASIK). We compared the reliability of swept-source OCT and Scheimpflug Imaging for evaluation of cornea
Renato Ambrósio - One of the best experts on this subject based on the ideXlab platform.
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Repeatability and reproducibility of corneal deformation response parameters of dynamic ultra-high-speed Scheimpflug Imaging in keratoconus.
Journal of Cataract and Refractive Surgery, 2020Co-Authors: Robert Herber, Paolo Vinciguerra, Riccardo Vinciguerra, Bernardo Lopes, Frederik Raiskup, Lutz E Pillunat, Renato AmbrósioAbstract:Purpose To assess the repeatability and reproducibility of dynamic corneal response (DCR) parameters obtained by ultra-high-speed Scheimpflug Imaging (Corvis ST); in keratoconic patients. Setting Clinics in Germany, Italy, and Brazil. Design Prospective, observational study. Methods Patients were examined 3 times using 2 different dynamic Scheimpflug analyzers (Corvis ST) to obtain repeatability and reproducibility. The reliability of intraocular pressure (IOP), biomechanically corrected IOP (bIOP), pachymetry, and DCR parameters were assessed by the coefficient of repeatability, coefficient of variation (CoV), intraclass correlation coefficient (ICC), and within-subject standard deviation (sw). Results Ninety-eight eyes from 98 KC patients were included. The sw of the IOP and bIOP did not exceed 1.1 mm Hg. A CoV less than 10% was found in all DCR parameters and had a good to excellent accordance regarding the ICC. The Corvis Biomechanical Index showed an excellent repeatability and interdevice reproducibility of 0.918 and 0.827, respectively. Also, the tomographic biomechanical index showed an excellent repeatability of 3 Corvis ST and Pentacam measurements (ICC = 0.997). With regard to keratoconic severity, a significant increase in the CoV was found between mild and moderate stages compared with the advanced stage. Nevertheless, it did not exceed 10% of the CoV in severe keratoconic eyes. Conclusion Corvis ST measurements in keratoconic eyes were highly repeatable and reproducible.
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comparison of objective and subjective refractive surgery screening parameters between regular and high resolution Scheimpflug Imaging devices
Journal of Cataract and Refractive Surgery, 2015Co-Authors: Bradley J Randleman, Renato Ambrósio, Ronald R Krueger, Jihan Akhtar, Michael J Lynn, William J Dupps, Stephen D KlyceAbstract:Purpose To compare objective and subjective metrics from regular and high-resolution Scheimpflug devices (Pentacam) to determine their equivalence and interchangeability for refractive surgery screening. Setting Emory Vision at Emory University, Atlanta, Georgia, USA. Design Retrospective comparative case series. Methods Eyes of consecutive screened refractive surgery patients were evaluated with high-resolution and regular Scheimpflug devices. Objective parameters evaluated included keratometry (K) values, central corneal thickness (CCT), and device-generated keratoconus screening indices. Masked expert reviewers subjectively graded images as normal, suspicious, or abnormal. Results One hundred eyes of 50 patients were evaluated. The mean K values were not significantly different (anterior K: high resolution 1.21 diopters [D] ± 1.13 (SD) versus regular 1.15 ± 1.16 D, P = 0.73; posterior K: 0.34 ± 0.23 D versus regular 0.35 ± 0.23 D, P = .67). The mean CCT was significantly thinner in the high-resolution group (514.7 ± 26.6 μm versus 527.6 ± 27.6 μm (P Conclusions Regular and high-resolution Scheimpflug Imaging devices generated different objective values and significantly different subjective interpretations with poor inter-reviewer agreement. The high-resolution device provided a more conservative overall output. For refractive surgical screening, the 2 devices are not interchangeable. Financial Disclosure Proprietary or commercial disclosures are listed after the references.
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Impact of chamber pressure and material properties on the deformation response of corneal models measured by dynamic ultra-high-speed Scheimpflug Imaging.
Arquivos Brasileiros De Oftalmologia, 2013Co-Authors: Fernando Faria Correia, Isaac Ramos, Andreas Steinmueller, Cynthia J. Roberts, Matthias Krug, Renato AmbrósioAbstract:PURPOSE: To study the deformation response of three distinct contact lenses with known structures, which served as corneal models, under different chamber pressures using ultra-high-speed (UHS) Scheimpflug Imaging. METHODS: Three hydrophilic contact lenses were mounted on a sealed water chamber with precisely adjustable pressure: TAN-G5X (41% hydroxyethylmethacrylate/glycolmethacrylate, 550 µm thick), TAN-40 (62% hydroxyethylmethacrylate, 525 µm thick) and TAN-58 (42% methylmethacrylate, 258 µm thick). Each model was tested five times under different pressures (5, 15, 25, 35 and 45 mmHg), using ultra-high-speed Scheimpflug Imaging during non-contact tonometry. 140 Scheimpflug images were taken with the UHS camera in each measurement. The deformation amplitude during non-contact tonometry was determined as the highest displacement of the apex at the highest concavity (HC) moment. RESULTS: At each pressure level, the deformation amplitude was statistically different for each lens tested (p
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impact of chamber pressure and material properties on the deformation response of corneal models measured by dynamic ultra high speed Scheimpflug Imaging
Arquivos Brasileiros De Oftalmologia, 2013Co-Authors: Fernando Faria Correia, Isaac Ramos, Andreas Steinmueller, Cynthia J. Roberts, Matthias Krug, Renato AmbrósioAbstract:PURPOSE: To study the deformation response of three distinct contact lenses with known structures, which served as corneal models, under different chamber pressures using ultra-high-speed (UHS) Scheimpflug Imaging. METHODS: Three hydrophilic contact lenses were mounted on a sealed water chamber with precisely adjustable pressure: TAN-G5X (41% hydroxyethylmethacrylate/glycolmethacrylate, 550 µm thick), TAN-40 (62% hydroxyethylmethacrylate, 525 µm thick) and TAN-58 (42% methylmethacrylate, 258 µm thick). Each model was tested five times under different pressures (5, 15, 25, 35 and 45 mmHg), using ultra-high-speed Scheimpflug Imaging during non-contact tonometry. 140 Scheimpflug images were taken with the UHS camera in each measurement. The deformation amplitude during non-contact tonometry was determined as the highest displacement of the apex at the highest concavity (HC) moment. RESULTS: At each pressure level, the deformation amplitude was statistically different for each lens tested (p<0.001, ANOVA). Each lens had different deformation amplitudes under different pressure levels (p<0.001; Bonferroni post-hoc test). The thicker lens with less polymer (TAN-G5X) had a higher deformation (less stiff behavior) than the one that was thinner but with more polymer (TAN-40), when measured at the same internal pressure. The thinnest lens with less polymers (TAN-58) had a lower deformation amplitude (stiffer behavior) at higher pressures than the thicker ones with more polymer (TAN-40 and TAN-G5X) at lower pressures. CONCLUSIONS: UHS Scheimpflug Imaging allowed for biomechanical assessment through deformation characterization of corneal models. Biomechanical behavior was more influenced by material composition than by thickness. Chamber pressure had a significant impact on deformation response of each lens.
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Scheimpflug Imaging for keratoconus and ectatic disease.
Indian Journal of Ophthalmology, 2013Co-Authors: Michael W. Belin, Renato AmbrósioAbstract:Scheimpflug cross-sectioning anterior segment Imaging offers significant advantages over traditional placido based curvature analysis and ultrasound pachymetry. The accurate measurement of both the anterior and posterior corneal surfaces and the anterior and posterior lens allows for the creation of a three-dimensional reconstruction of the anterior segment. Changes on both the posterior cornea and/or corneal thickness map are earlier indicators of ectatic change than would otherwise be identifiable with only anterior curvature and ultrasonic pachymetry. Scheimpflug Imaging also covers significantly more of the cornea than was possible with placido based devices. This added coverage is critical in the proper diagnosis of peripheral diseases such as pellucid marginal degeneration (PMD).
