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

Abstract

. 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.

A Review of Feasible Applications of THz Waves in Medical Diagnostics and Treatments

“…The relationship between corneal pathology changes due to B-band ultraviolet (UVB) radiation and parameters derived from the THz reflection coefficient of rabbit cornea has been investigated. 53 In an in vivo test, the amount of water in the cornea was measured simultaneously with the RC reflection coefficient. In general, corneal hydration can be determined with the help of the THz reflection coefficient, which can be effective in eye pathology.…”

Investigating the Impact of Synchrotron THz Radiation on the Corneal Hydration Using Synchrotron THz-Far Infrared Beamline

“…For instance, Iomdina et al, reported on the study of transmittance and reflectance of the cornea and sclera in the range of 0.13 to 0.32 THz followed by exposure to a backward-wave oscillator (BWO) with an effective bandwidth frequency of 10 MHz [ 13 ]. In another study, they explored the THz scanning of hydration of corneal tissue followed by damage caused by B-band ultraviolet (UVB) exposure at 50 Hz [ 14 ], while some studies have investigated THz sensing of ocular tissues, no studies have previously reported on the use of synchrotron continuous THz radiation source for both exposing and evaluating biological changes in corneal tissues or other ocular tissues. Furthermore, the mentioned studies do not contain the frequencies under consideration for this paper.…”

Cellular effects of terahertz waves

“…1 ), has been observed during the past few decades, 1 – 5 driven by rapid progress in THz technology. 6 , 7 Numerous research papers demonstrate the potential of THz technology in label-free early noninvasive, least-invasive, and intraoperative diagnosis of malignant and benign neoplasms with different nosologies and localizations, 3 , 4 , 8 – 18 sensing of glycated tissues and blood in the context of diabetes diagnosis, 1 , 19 – 21 determining the degree of traumatic injuries, 22 – 25 hydration levels, 26 – 29 and viability 30 of tissues. Along with the diagnostic applications, THz technology holds strong potential in therapeutics, 31 , 32 for example, in nonthermal regulation in expression of genes associated with cancer and inflammatory diseases.…”