Application of THz reflectometry to eye cornea hydration measurements

Angeluts, A. A.; Balakin, A. V.; Mishchenko, M. D.; Ozheredov, I. A.; Prokopchuk, Mikhail; Saphonova, T. N.; Shkurinov, A. P.

doi:10.1109/irmmw-thz.2016.7758909

Cited by 4 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The cornea phantom's en-face diameter was 12 mm. Twelve (12) phantoms were fabricated for this work, six 0.58mm thick phantoms and six 0.68-mm thick phantoms. The phantoms are labeled A -L in the order they were measured (Figure 5).…”

Section: Corneal Phantommentioning

confidence: 99%

“…Significant work has been carried out to measure millimeter-wave and THz reflectivity from corneas and corneal phantoms [5], [6], [7], [8], [9], [10], and [11]. Some of the measurement campaigns have characterized corneal tissue reflectivity in a qualitative manner, where a transition is observed when the cornea, e.g., dries or hydrates [12], [13]. The in vivo measurements are easily disturbed by alignment issues due to the subject in constant movement.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Extraction of Thickness and Water-Content Gradients in Hydrogel-Based Water-Backed Corneal Phantoms Via Submillimeter-Wave Reflectometry

Tamminen

Baggio

Nefedova

et al. 2021

IEEE Trans. THz Sci. Technol.

View full text Add to dashboard Cite

Absolute thickness and free water content gradients in gelatinbased corneal phantoms with physiologically accurate radii of curvature, and aqueous backing were extracted via coherent submillimeter wave reflectometry at 220 -330 GHz. Fourier-domain based calibration methods, utilizing temporal and spatial gating, were developed and yielded peak-topeak amplitude and phase clutter of 10 -3 and 0.1°, respectively for signal to noise ratios between 40 dB and 50 dB. Twelve phantoms were fabricated. Calibration methods enabled quantification of target sphericity that strongly correlated with optical coherence tomography-based sphericity metrics via image segmentation. Extracted free water volume fraction varied less than 5 % in the 5 phantoms whose fabrication yielded the most spherical geometry. Submillimeter wave-based thickness accuracy was better than 111 μm (~λ/9) with average of 65 μm (~λ/17) and standard deviation of 44 μm (~λ/25) for phantoms with physiologically relevant geometry. MonteCarlo simulations of measurement noise and uncertainty limits agree with experimental data analysis and indicates a lower thickness accuracy limit of 33 μm, and water content sensitivities of 0.5 % and 11.8 % for the anterior and posterior segments respectively. Numerical analysis suggests measurement fidelity was SNR limited and identified optical path length ambiguities within the cornea where a continuum of thickness/water gradient pairs produce statistically insignificant differences in complex reflection coefficient for finite SNR. This is the first known submillimeterwave measurement technique able to extract both the thickness and water content gradients from a soft-tissue phantom, with a water backing, without the need for ancillary measurements.

show abstract

Section: Corneal Phantommentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extraction of Thickness and Water-Content Gradients in Hydrogel-Based Water-Backed Corneal Phantoms Via Submillimeter-Wave Reflectometry

Tamminen

Baggio

Nefedova

et al. 2021

IEEE Trans. THz Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…В одном из относительно недавних исследований описана модель прибора на основе импульсной терагерцовой рефлектометрии, который предположительно можно использовать для диагностики ССГ [57]. Возможности этого метода проанализированы на модели, максимально приближенной к глазу человека, а также на 3 здоровых волонтерах.…”

Section: Hеинвазивное время разрыва слезной пленкиunclassified

Current methods of tear film stability assessment

2019

Self Cite

View full text Add to dashboard Cite

По результатам проведения Международного симпозиума по cиндрому «cухого глаза» (The 2007 International Dry Eye WorkShop, DEWS) при поддержке Общества специалистов по изучению слезной пленки и глазной поверхности (The Tear Film & Ocular Surface Society, TFOS) в 2007 г. принято решение об официальном введении термина «си-стема глазной поверхности» («Ocular Surface System») в медицинскую номенклатуру. Система глазной поверхности представляет собой непрерывный слой эпителия, покрывающего глазную поверхность (т.е. эпителий роговицы и конъюнктивы) вместе с эпителием ацинусов главной и добавочных слезных желез, мейбомиевых желез и слезных канальцев. Эпи

show abstract

“…Millimeter-wave (mmW)-to-THz frequency mapping of corneal tissue water content (CTWC) continues to generate interest in the high frequency RF and photonics communities with increasing support from ophthalmology and related clinical specialties [1][2][3][4][5][6][7][8]. CTWC is currently difficult to quantify in vivo and abnormal increases in tissue hydration are associated with a number of corneal diseases [9][10][11] and correlated with tissue viability following various surgical procedures [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

Baggio

Dabironezare

et al. 2022

IEEE Trans. THz Sci. Technol.

View full text Add to dashboard Cite

A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing 5 off-axis parabolic mirrors, a thin film beam splitter, and 2-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.

show abstract

Application of THz reflectometry to eye cornea hydration measurements

Cited by 4 publications

References 3 publications

Extraction of Thickness and Water-Content Gradients in Hydrogel-Based Water-Backed Corneal Phantoms Via Submillimeter-Wave Reflectometry

Extraction of Thickness and Water-Content Gradients in Hydrogel-Based Water-Backed Corneal Phantoms Via Submillimeter-Wave Reflectometry

Current methods of tear film stability assessment

650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

Contact Info

Product

Resources

About