Terahertz optical properties of the cornea

Liu, Wenquan; Lu, Yuanfu; Jiao, Guohua; Chen, Xianfeng; Li, Jinying; Chen, Sihai; Dong, Yuanhua; Lv, Jiancheng

doi:10.1016/j.optcom.2015.09.107

Cited by 17 publications

(10 citation statements)

References 30 publications

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“…In their work, the authors used a THz spectrometer with an optimized scanning speed. In another study 23 by the same authors, the method of time-resolved THz spectroscopy was used for in vitro studies of the dependence of the reflection and transmission coefficients of the cornea in the range of 0.1 to 1.5 THz. The results show that the reflection coefficient decreases with increasing radiation frequency, while the absorption coefficient, on the contrary, increases, and it is almost linear.…”

Section: Introductionmentioning

confidence: 99%

Terahertz scanning of the rabbit cornea with experimental UVB-induced damage: in vivo assessment of hydration and its verification

et al. 2021

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. Significance: Water content plays a vital role in the normally functioning visual system; even a minor disruption in the water balance may be harmful. Today, no direct method exists for corneal hydration assessment, while it could be instrumental in early diagnosis and control of a variety of eye diseases. The use of terahertz (THz) radiation, which is highly sensitive to water content, appears to be very promising. Aim: To find out how THz scanning parameters of corneal tissue measured by an experimental setup, specially developed for in vivo contactless estimations of corneal reflectivity coefficient (RC), are related to pathological changes in the cornea caused by B-band ultraviolet (UVB) exposure. Approach: The setup was tested on rabbit eyes in vivo . Prior to the course of UVB irradiation and 1, 5, and 30 days after it, a series of examinations of the corneal state was made. At the same time points, corneal hydration was assessed by measuring RC. Results: The obtained data confirmed the negative impact of UVB irradiation course on the intensity of tear production and on the corneal thickness and optical parameters. A significant (1.8 times) increase in RC on the 5th day after the irradiation course, followed by a slight decrease on the 30th day after it was revealed. The RC increase measured 5 days after the UVB irradiation course generally corresponded to the increase (by a factor of 1.3) of tear production. RC increase occurred with the corneal edema, which was manifested by corneal thickening (by 18.2% in the middle area and 17.6% in corneal periphery) and an increased volume of corneal tissue (by 17.6%). Conclusions: Our results demonstrate that the proposed approach can be used for in vivo contactless estimation of the reflectivity of rabbit cornea in the THz range and, thereby, of cornea hydration.

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Section: Introductionmentioning

confidence: 99%

Terahertz scanning of the rabbit cornea with experimental UVB-induced damage: in vivo assessment of hydration and its verification

et al. 2021

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“…Based on corneal physiology, different factors affecting corneal tissue water content were selected as perturbations, and systematic simulation for the effects on the water distribution and total thickness have been done. Liu et al 20 detected the optical properties of ex vivo rabbit corneal tissues with different water content at THz frequencies and discovered that the absorption coefficient and refractive index of a hydrated cornea were much larger than that of a dehydrated cornea. Recently, researchers from Lomonosov Moscow State University [21][22][23][24] developed THz simplified dielectric permittivity model of water and water-containing media by considering cornea as a homogeneous medium, compared with relatively larger wavelength in THz range, and quantitative calculation of the physiological dynamics of tear film and hydration were reported.…”

Section: Introductionmentioning

confidence: 99%

Terahertz spectroscopy analysis of human corneal sublayers

Zhang

et al. 2021

J. Biomed. Opt.

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“…Recently, terahertz (THz) wave has been proposed as a safe and sensitive method to probe CTWC owing to its low photon energy and high sensitivity to water [17][18][19][20]. Previous reports use THz reflectivity as the key parameter to extract the corneal hydration level.…”

Section: Introductionmentioning

confidence: 99%

Corneal hydration assessment indicator based on terahertz time domain spectroscopy

Yao¹,

Ma²,

Zhao³

et al. 2020

Biomed. Opt. Express

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Terahertz technology has shown broad prospects for measuring corneal water content, which is an important parameter of ocular health. Based on terahertz time-domain spectroscopy, a new indicator named characteristic ratio (CR) of the sum of low (0.2-0.7 THz) and high (0.7-1.0 THz) frequency spectral intensities, for characterizing corneal hydration is introduced in this work. CR is calculated from the real-time reflection spectra after error elimination of ex vivo human corneal stroma samples which is collected during dehydration under natural conditions (temperature: 22.4 ± 0.3°C; humidity: 20.0 ± 3%). The corresponding relationships between CR and corneal water content are reported. Comparing the linear fitting results with the published similar study, the coefficients of variation of the fitting slope and intercept are 39.4% and 27.6% lower, respectively. This indicates that this approach has the potential to achieve corneal water content in-vivo detection in the future.

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Terahertz optical properties of the cornea

Cited by 17 publications

References 30 publications

Terahertz scanning of the rabbit cornea with experimental UVB-induced damage: in vivo assessment of hydration and its verification

Terahertz scanning of the rabbit cornea with experimental UVB-induced damage: in vivo assessment of hydration and its verification

Terahertz spectroscopy analysis of human corneal sublayers

Corneal hydration assessment indicator based on terahertz time domain spectroscopy

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