Scheimpflug camera in the quantitative assessment of reproducibility of high-speed corneal deformation during intraocular pressure measurement

2015 ◽  
Vol 8 (11-12) ◽  
pp. 968-978 ◽  
Author(s):  
Robert Koprowski ◽  
Renato Ambrósio ◽  
Sven Reisdorf
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement ◽  
High Speed ◽  
Quantitative Assessment ◽  
Scheimpflug Camera ◽  
Corneal Deformation

scholarly journals Novel Method of Measuring Corneal Viscoelasticity Using the Corvis ST Tonometer

2022 ◽  
Vol 11 (1) ◽  
pp. 261
Author(s):  
Agnieszka Boszczyk ◽  
Henryk Kasprzak ◽  
Joanna Przeździecka-Dołyk
Keyword(s):  
Intraocular Pressure ◽  
Viscoelastic Properties ◽  
High Speed ◽  
Central Area ◽  
Biomechanical Properties ◽  
P Value ◽  
Corvis St ◽  
Corneal Deformation ◽  
The Times ◽  
High Repeatability

Background: The process of rapid propagation of the corneal deformation in air puff tonometer depends not only on intraocular pressure, but also on the biomechanical properties of the cornea and anterior eye. One of the biomechanical properties of the cornea is viscoelasticity, which is the most visible in its high-speed deformations. It seems reasonable to link the corneal viscoelasticity parameter to two moments of the highest speed of corneal deformations, when the cornea buckles. The aim of this work is to present a method of determining the time and place of occurrence of corneal buckling, examine spatial and temporal dependencies between two corneal applanations and bucklings in the Corvis ST tonometer, and correlate these dependencies with corneal viscoelastic properties. Methods: Images of the horizontal cross section of the Corvis ST deformed cornea from the air puff tonometer Corvis ST were used. 14 volunteers participated in the study, each of them had one eye measured eight times. Mutual changes in the profile slopes of the deformed corneas were numerically determined. They describe pure corneal deformation, eliminating the influence of rotation, and displacement of the entire eyeball. For each point in the central area of the corneal profile, the maximum velocities of mutual slope changes accompanying the applanations were estimated. The times of their occurrence were adopted as buckling times. Results: The propagation of buckling along the corneal profile is presented, as well as the repeatability and mutual correlations between the buckling parameters and intraocular pressure. Based on the relationship between them, a new parameter describing corneal hysteresis: Corvis Viscoelasticity (CVE) is introduced. It is characterized by high repeatability: ICC = 0.82 (0.69–0.93 CI) and low and insignificant correlation with intraocular pressure: r = 0.25 (p-value = 0.38). Conclusion: The results show for the first time how to measure the corneal buckling and viscoelastic effects with Corvis ST. CVE is a new proposed biomechanical parameter related to the viscoelastic properties of the cornea, which has high repeatability for the examined subject. The distribution of its values is planned to be tested on different groups of patients in order to investigate its clinical applicability.

scholarly journals First Clinical Impressions on the Integrated Corneal Tomography and Corneal Deformation with Scheimpflug Imaging

2017 ◽  
Vol 6 (2) ◽  
pp. 101-109
Author(s):  
Jorge S Haddad ◽  
Eliza Barnwell ◽  
Karolinne M Rocha ◽  
George O Waring IV ◽  
Renato Ambrosio Jr
Keyword(s):  
Clinical Data ◽  
High Speed ◽  
Imaging System ◽  
Corneal Ectasia ◽  
Scheimpflug Camera ◽  
Deformation Parameters ◽  
Corneal Deformation ◽  
Scheimpflug Imaging ◽  
Noncontact Tonometer ◽  
Corneal Tomography

ABSTRACT The purpose of this study is to report the preliminary findings and the retrospective clinical impressions of the integrated corneal tomography and corneal deformation parameters with a dynamic ultra-high-speed Scheimpflug camera equipped with a noncontact tonometer. Twelve eyes of six patients were evaluated by the Scheimpflug imaging system of the Pentacam HR and Corvis ST (OCULUS Optikgeräte GmbH, Wetzlar, Germany) devices. The parameters used were the Belin/Ambrósio deviation (BAD-D) and Corvis biomechanical index (CBI), as well as the recently published tomographic and biomechanical index (TBI), combined with a detailed clinical data and evaluation of normal eyes and patients with different stages of corneal ectasia. How to cite this article Haddad JS, Barnwell E, Rocha KM, Waring IV GO, Ambrosio Jr R. First Clinical Impressions on the Integrated Corneal Tomography and Corneal Deformation with Scheimpflug Imaging. Int J Kerat Ect Cor Dis 2017;6(2):101-109.

Comparison of Corneal Deformation Parameters in Keratoconic and Normal Eyes Using a Non-contact Tonometer With a Dynamic Ultra-High-Speed Scheimpflug Camera

2017 ◽  
Vol 33 (9) ◽  
pp. 625-631 ◽  
Author(s):  
Ryan N. Mercer ◽  
George O. Waring ◽  
Cynthia J. Roberts ◽  
Vishal Jhanji ◽  
Yumeng Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Scheimpflug Camera ◽  
Deformation Parameters ◽  
Ultra High Speed ◽  
Corneal Deformation

scholarly journals Impact of diurnal IOP variations on the dynamic corneal hysteresis measured with air-puff swept-source OCT

2018 ◽  
Vol 10 (3) ◽  
pp. 64
Author(s):  
Karol Marian Karnowski ◽  
Ewa Mączyńska ◽  
Maciej Nowakowski ◽  
Bartłomiej Kałużny ◽  
Ireneusz Grulkowski ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
High Speed ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Biomedical Optics ◽  
Corneal Hysteresis ◽  
Swept Source ◽  
Corneal Deformation ◽  
Swept Source Oct ◽  
Diurnal Iop

The deformation amplitudes measured with air-puff OCT are sensitive to both (intraocular pressure) IOP and biomechanical properties of the cornea. Analysis of the amplitudes of corneal deformation is challenging due to interrelation of IOP and corneal biomechanics. In this study, we used natural diurnal IOP fluctuations to investigate corneal deformations in a number of subjects whose eyes were measured multiple times during a day. The results of analysis, based on corneal hysteresis, revealed a corneal hysteresis parameter, which remains constant during a day for each individual eye. We hypothesize that above-mentioned metric might correlate with biomechanical properties of the cornea without influence of IOP. Full Text: PDF ReferencesMeek KM, Tuft SJ, Huang Y, Gill PS, Hayes S, Newton RH, Bron AJ, "Changes in Collagen Orientation and Distribution in Keratoconus Corneas", Invest Ophthalmol Vis Sci, 2005. 46(6): p. 1948-56. CrossRef Zimmermann DR, Fisher RW, Winterhalter KH, Witmer R, Vaughan L, "Comparative studies of collagens in normal and keratoconus corneas", Exp Eye Res, 1988. 46(3): p. 431-42. CrossRef Andreassen TT, Simonsen AH, and Oxlund H, "Biomechanical properties of keratoconus and normal corneas", Experimental Eye Research, 1980. 31(4): p. 435-441. CrossRef Heijl A, Leske MC, Bengtsson B, Hyman L, Bengtsson B, Hussein M, "Reduction of Intraocular Pressure and Glaucoma Progression", Arch Ophthalmol, 2002. 120(10): p. 1268-79. CrossRef Chauhan BC and Drance SM, "The influence of intraocular pressure on visual field damage in patients with normal-tension and high-tension glaucoma", Investigative Ophthalmology & Visual Science, 1990. 31(11): p. 2367-2372. DirectLink Gelaw Y, "The impact of central corneal thickness on intraocular pressure among Ethiopian glaucoma patients: a cross-sectional study", BMC Ophthalmology, 2012. 12(1): p. 58. CrossRef Doughty MJ and Zaman ML, "Human Corneal Thickness and Its Impact on Intraocular Pressure Measures: A Review and Meta-analysis Approach", Surv Ophthalmol, 2000. 44(5): p. 367-408. CrossRef Liu J, and Roberts CJ, "Influence of corneal biomechanical properties on intraocular pressure measurement: Quantitative analysis", J Cataract Refract Surg, 2005. 31(1): p. 146-55. CrossRef Ehlers N, Hansen FK, and Aasved H, "Biometric Correlations of Corneal Thickness", Acta Ophthalmol (Copenh), 1975. 53(4): p. 652-9. CrossRef Harada Y, Hirose N, Tawara A, "The Influence of Central Corneal Thickness and Corneal Curvature Radius on The Intraocular Pressure as Measured By Different Tonometers: Noncontact and Goldmann Applanation Tonometers", J Glaucoma, 2008. 17(8): p. 619-25. CrossRef Alonso-Caneiro D, Karnowski K, Kaluzny BJ, Kowalczyk A, Wojtkowski M, "Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system", Optics Express, 2011. 19(15): p. 14188-14199. CrossRef Dorronsoro C, Pascual D, Perez-Merino P, Kling S and Marcos S, "Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas", Biomedical Optics Express, 2012. 3(3): p. 473-487. CrossRef Karnowski K, Kaluzny BJ, Szkulmowski M, Gora M, Wojtkowski M, "Corneal topography with high-speed swept source OCT in clinical examination", Biomedical Optics Express, 2011. 2(9): p. 2709-2720. CrossRef A. N. S. Institute, "American National Standard for Safe use of Lasers," (American National Standards Institute, Orlando, FL, 2000) DirectLink David R, Zangwill L, Briscoe D, Dagan M, Yagev R, Yassur Y, "Diurnal intraocular pressure variations: an analysis of 690 diurnal curves", Br J Ophthamlom, 1992, 76(5): p. 280-282 CrossRef Maczynska E, Karnowski K, Szulzycki K, Malinowska M, Dolezyczek H, Cichanski A, Wojtkowski M, Kaluzny BJ, Grulkowski I, Journal of Biophotonics (to be published).

scholarly journals Effects of age on corneal deformation by non-contact tonometry integrated with an ultra-high-speed (UHS) Scheimpflug camera

2013 ◽  
Vol 76 (4) ◽  
pp. 229-232 ◽  
Author(s):  
Bruno Freitas Valbon ◽  
Renato Ambrósio-Jr. ◽  
Bruno Machado Fontes ◽  
Milton Ruiz Alves
Keyword(s):  
High Speed ◽  
Scheimpflug Camera ◽  
Ultra High Speed ◽  
Corneal Deformation

scholarly journals Quantitative Assessment of the Impact of Blood Pulsation on Intraocular Pressure Measurement Results in Healthy Subjects

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Robert Koprowski ◽  
Lei Tian
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement ◽  
Pulse Oximeter ◽  
Healthy Subjects ◽  
Pressure Measurements ◽  
Left Hand ◽  
Corneal Deformation ◽  
Measurement Results ◽  
The Moment ◽  
The Impact

Background. Blood pulsation affects the results obtained using various medical devices in many different ways. Method. The paper proves the effect of blood pulsation on intraocular pressure measurements. Six measurements for each of the 10 healthy subjects were performed in various phases of blood pulsation. A total of 8400 corneal deformation images were recorded. The results of intraocular pressure measurements were related to the results of heartbeat phases measured with a pulse oximeter placed on the index finger of the subject’s left hand. Results. The correlation between the heartbeat phase measured with a pulse oximeter and intraocular pressure is 0.69±0.26 (p<0.05). The phase shift calculated for the maximum correlation is equal to 60±40° (p<0.05). When the moment of measuring intraocular pressure with an air-puff tonometer is not synchronized, the changes in IOP for the analysed group of subjects can vary in the range of ±2.31 mmHg (p<0.3). Conclusions. Blood pulsation has a statistically significant effect on the results of intraocular pressure measurement. For this reason, in modern ophthalmic devices, the measurement should be synchronized with the heartbeat phases. The paper proposes an additional method for synchronizing the time of pressure measurement with the blood pulsation phase.

Method for prediction of development of neurodegenerative diseases withgamma-sinuclein dysfunction using pressure measurement after ocularinstallations of dopaminergic system on the intraocular pressure

2020 ◽  
pp. 78-79
Author(s):  
V.S. Ogorodnik ◽  
◽  
T.A. Pavlenko ◽  
A.V. Grigoryev ◽  
O.V. Beznos ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Neurodegenerative Diseases ◽  
Pressure Measurement ◽  
Dopaminergic System

Актуальность. Патологическая агрегация γ-синуклеина, одного из членов семейства синуклеинов, ассоциирована не только с болезнью Паркинсона, боковым амиотрофическим склерозом, но и с развитием глаукомы. Данный белок, являясь синаптическим, участвует в процессе везикулярного транспорта и высвобождении медиаторов, в частности дофамина. Цель. Обоснование возможности прогнозирования нарушения функции γ-синуклеина по влиянию регуляторов дофаминергической системы на уровень ВГД. Материал и методы. У 15 мышей (30 глаз) синактивированным геном, кодирующим γ-синуклеин (γ-KO) из лаборатории V. Buchman (TheJackson Laboratory – B6.129P2-Sncgtm1Vlb/J и008843) и у 20 контрольных мышей дикого типа (40глаз) того же возраста (2,5-3,5 месяцев) проводили измерение внутриглазного давления (ВГД) до и после однократной инстилляции по 10 мкл в оба глазарегуляторов дофаминергической системы (мелатонина 0,1%, Галоперидола 0,2%, дофамина 10%).Мышам проводили измерение ВГД через каждые30 минут в течение двух часов. Для каждого препарата-регулятора формировалась отдельная группа мышей. Результаты. У мышей γ-KO выявлено снижение ВГД в течение 2 часов более, чем на 4-5 ммрт. ст в ответ на инстилляцию мелатонина 0,1%(р<0,03), Галоперидола 0,2% (р<0,03) и дофамина10% (р<0,03) по сравнению с мышами дикого типа, где наблюдалось незначительное снижение уровня ВГД соответствующих регуляторов. Выводы. Предложенный способ измерения ВГД после инстилляции препаратов, влияющих на метаболизм дофамина, позволяет выявлять и прогнозировать развитие недостаточности функции γ-синуклеина и его влияние на регуляцию ВГД и формировать группы риска для динамического наблюдения и выбора превентивных лечебных мероприятий.

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