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Iomdina, E. N.; Seliverstov, S. V.; Sianosyan, A. A.; Teplyakova, K. O.; Rusova, A. A.; Goltsman, G. N. |
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Title |
Terahertz scanning for evaluation of corneal and scleral hydration |
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Journal Article |
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Year |
2018 |
Publication |
Sovremennye tehnologii v medicine |
Abbreviated Journal |
STM |
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10 |
Issue |
4 |
Pages |
143-149 |
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Keywords |
BWO; Golay cell; medicine; cornea; sclera; THz radiation; corneal hydration; backward-wave oscillator; avalanche transit-time diode; IMPATT diode |
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Abstract |
The aim of the investigation was to study the prospects of using continuous THz scanning of the cornea and the sclera to determine water concentration in these tissues and on the basis of the obtained data to develop the experimental installation for monitoring corneal and scleral hydration degree.Materials and Methods. To evaluate corneal and scleral transmittance and reflectance spectra in the THz range, the developed experimental installations were used to study 3 rabbit corneas and 3 scleras, 2 whole rabbit eyes, and 3 human scleras. Besides, two rabbit eyes were studied in vivo prior to keratorefractive surgery as well as 10 and 21 days following the surgery (LASIK).Results. There have been created novel experimental installations enabling in vitro evaluation of frequency dependence of corneal and scleral transmittance coefficients and reflectance coefficients on water percentage in the THz range. Decrease in corneal water content by 1% was found to lead to reliably established decrease in the reflected signal by 13%. The reflectance spectrum of the whole rabbit eye was measured in the range of 0.13–0.32 THz. The study revealed the differences between the indices of rabbit cornea and sclera, as well as rabbit and human sclera. There was developed a laboratory model of the installation for in vivo evaluation of corneal and scleral hydration using THz radiation.Conclusion. The preliminary findings show that the proposed technique based on the use of continuous THz radiation can be employed to create a device for noninvasive control of corneal and scleral hydration. |
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1315 |
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Iomdina, E. N.; Seliverstov, S.; Sianosyan, A.; Teplyakova, K.; Rusova, A.; Goltsman, G. |
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Title |
The prospects of using the radiation for the assessment of corneal and scleral hydration |
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Abstract |
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2016 |
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Acta Ophthalmol. |
Abbreviated Journal |
Acta Ophthalmol. |
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94 |
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BWO, avalanche transit‐time diode, medicine, biology |
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Abstract |
Purpose
An adequate water balance (hydration extent) is one of the basic factors of normal eye function, including its external shells – the cornea and the sclera. THz systems creating images in reflected beams are likely to become ideal instruments of noninvasive testing of corneal and scleral hydration degree as THz radiation is highly sensitive to water content. The paper aims at studying the transmittance and reflectance spectra of the cornea and the sclera of rabbit and human eyes, as well as those of the whole rabbit eye, in the frequency range of 0.13–0.32 THz.
Methods
The experiments were carried out on 3 corneas and 3 rabbit scleras, 2 whole rabbit eyes, and 3 human healthy adult scleras using a specially developed THz system based on reliable and easy‐to‐use continuous wave sources: a backward‐wave oscillator and an avalanche transit‐time diode.
Results
The transmittance spectra of the cornea and the sclera and the dependence of the reflection coefficient of these tissues in THz range on water percentage content were determined. Comparison of the rabbit cornea hydrated from 73.2% to 76.3% concentration by mass demonstrated an approximately linear relationship between THz reflectivity and water concentration. The decrease of free water concentration by 1% leads to a drop of the reflectance coefficient by 13%. The parameters studied displayed noticeable differences between the sclera and the cornea of rabbits and between rabbit sclera and human sclera.
Conclusions
Preliminary results demonstrate that the proposed technique, based on continuous THz radiation, may be used to create a device for noninvasive testing of corneal and scleral hydration, which has good potential of wide‐scale practical application.
The work was supported by the Russian Foundation of Basic Research (grant No.15‐29‐03843) |
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1755375X |
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1333 |
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Iomdina, E. N.; Goltsman, G. N.; Seliverstov, S. V.; Sianosyan, A. A.; Teplyakova, K. O.; Rusova, A. A. |
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Study of transmittance and reflectance spectra of the cornea and the sclera in the THz frequency range |
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Journal Article |
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2016 |
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J. Biomed. Opt. |
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J. Biomed. Opt. |
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21 |
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9 |
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97002 (1 to 5) |
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BWO, IMPATT diode, Schottky diode, medicine, animals, cornea, physiology, humans, rabbits, sclera diagnostic imaging, physiology |
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An adequate water balance (hydration extent) is one of the basic factors of normal eye function, including its external shells: the cornea and the sclera. Adequate control of corneal and scleral hydration is very important for early diagnosis of a variety of eye diseases, stating indications for and contraindications against keratorefractive surgeries and the choice of contact lens correction solutions. THz systems of creating images in reflected beams are likely to become ideal instruments of noninvasive control of corneal and scleral hydration degrees. This paper reports on the results of a study involving transmittance and reflectance spectra for the cornea and the sclera of rabbit and human eyes, as well as those of the rabbit eye, in the frequency range of 0.13 to 0.32 THz. The dependence of the reflectance coefficient of these tissues on water mass percentage content was determined. The experiments were performed on three corneas, three rabbit scleras, two rabbit eyes, and three human scleras. The preliminary results demonstrate that the proposed technique, based on the use of a continuous THz radiation, may be utilized to create a device for noninvasive control of corneal and scleral hydration, which has clear potential of broad practical application. |
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Moscow State Pedagogical University, Department of Physics, 29 Malaya Pirogovskaya Street, Moscow 119435, Russia |
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English |
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1083-3668 |
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PMID:27626901 |
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1335 |
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Gol’tsman, G. N. |
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Terahertz technology in Russia |
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Conference Article |
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1994 |
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24th European Microwave Conf. |
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24th European Microwave Conf. |
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1 |
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113-121 |
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BWO, HEB mixers |
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The presentation consider the parameters and operating peculiarities of unique microwave generators of the terahertz range which have been created in Russia – the backward wave oscillators – as well as certain devices based on these generators, such as high resolution. spectrometers and time-resolving spectrometers with picosecond temporal resolution. Most resent BWO-based studies are illustrated by a project devoted to superconductive hot-electron. bolometers which are of great independent value for the terahertz technology as high-sensitive picosecond detectors and low noise broad-band mixers. |
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24th European Microwave Conference |
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1635 |
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Aksaev, E. E.; Gershenzon, E.M.; Gol'tsman, G. N.; Mirskij, G. I.; Semenov, A. D. |
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Submillimetric spectrometer-relaxometer based on backward-wave tubes with picosecond time resolution |
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1991 |
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Pribory i Tekhnika Eksperimenta |
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Pribory i Tekhnika Eksperimenta |
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34 |
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2 |
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125-131 |
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BWO, applications |
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The high-sensitive automatic spectrometer-relaxometer based on backward-wave tubes in the range of 4÷0.25 mm was described permitting to study the response kinetics of sample under investigation in any point of this range with the resolution time of 10-11 s. The relaxation measurements were conducted using oscillation beats of two adequate tubes, the frequency of one of them was fixed, while that of the other one was changeable. The amplitude-frequency characteristic of the response under the conditions of synchronous reception was recorded at beat frequency variation from 107 to 1010 Hz. The high sensitivity was reached by decreasing the device recording band down to 100 Hz in the whole measuring range. |
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0032-8162 |
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