Corvis ST tonometer and the possibility of analysing corneal deformation dynamics during intraocular pressure measurement

2019 ◽  
Author(s):  
Robert Koprowski
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement ◽  
Corvis St ◽  
Corneal Deformation ◽  
Deformation Dynamics

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.

Intraocular pressure measurement with Corvis ST in comparison with applanation tonometry and Tomey non-contact tonometry

2019 ◽  
Vol 39 (11) ◽  
pp. 2517-2521
Author(s):  
Jan Luebke ◽  
L. Bryniok ◽  
M. Neuburger ◽  
J. F. Jordan ◽  
D. Boehringer ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement ◽  
Applanation Tonometry ◽  
Corvis St

scholarly journals Repeatability of the Novel Intraocular Pressure Measurement From Corvis ST

2019 ◽  
Vol 8 (3) ◽  
pp. 48 ◽  
Author(s):  
Masato Matsuura ◽  
Hiroshi Murata ◽  
Yuri Fujino ◽  
Mieko Yanagisawa ◽  
Yoshitaka Nakao ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement ◽  
The Novel ◽  
Corvis St

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.

A COMPARISON OF INTRAOCULAR PRESSURE MEASUREMENT IN VARYING LATERAL AND MEDIAL GAZES

1994 ◽  
Vol 71 (Supplement) ◽  
pp. 106
Author(s):  
Wendy Kumata ◽  
John H. Nishimoto ◽  
Cherilyn Lai ◽  
Paul N. DeLand
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurement
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