Laser reshaping of costal cartilage for transplantation

Self Cite

We describe the use of elastographic processing in phase-sensitive optical coherence tomography (OCT) for visualizing dynamics of strain and tissue-shape changes during laser-induced photothermal corneal reshaping, for applications in the emerging field of non-destructive and non-ablative (non-LASIK) laser vision correction. The proposed phase-processing approach based on fairly sparse data acquisition enabled rapid data processing and near-real-time visualization of dynamic strains. The approach avoids conventional phase unwrapping, yet allows for mapping strains even for significantly supra-wavelength inter-frame displacements of scatterers accompanied by multiple phase-wrapping. These developments bode well for real-time feedback systems for controlling the dynamics of corneal deformation with 10-100 ms temporal resolution, and for suitably long-term monitoring of resultant reshaping of the cornea. In ex-vivo experiments with excised rabbit eyes, we demonstrate temporal plastification of cornea that allows shape changes relevant for vision-correction applications without affecting its transparency. We demonstrate OCT's ability to detect achieving of threshold temperatures required for tissue plastification and simultaneously characterize transient and cumulative strain distributions, surface displacements, and scattering tissue properties. Comparison with previously used methods for studying laser-induced reshaping of cartilaginous tissues and numerical simulations is performed.

Section: Discussionsupporting

confidence: 62%

Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape

Zaitsev

Matveyev

Matveev

et al. 2017

Self Cite

“…Laser‐induced modification of cartilaginous tissue for medical applications uses the moderate energy modes when the tissue is heated on tens of degrees for short times below the thresholds of thermal alterations of the tissue components . In some cases like cartilage reshaping the needed temperature for stress relaxation may exceed the equilibrium denaturation temperature, however, at short pulses the tissue cooling is much faster than the phase transformation has time to occur.…”

Section: Resultsmentioning

confidence: 99%

“…A perspective technology of infrared (IR) laser reshaping of cartilage in larynx stenosis surgery implies the usage of autologous costal cartilage implants to be extracted from the patient rib, irradiated to obtain stable semicircle shape and implanted to cover the trachea defect during a single operation procedure . IR laser‐induced temperature of around 70 °C is the critical parameter needed for effective relaxation of internal mechanical stress and obtaining of a new shape .…”

Section: Introductionmentioning

confidence: 99%

Control of optical transparency and infrared laser heating of costal cartilage via injection of iohexol

Alexandrovskaya

Evtushenko

Obrezkova

et al. 2018

Self Cite

Infrared (IR) laser impact has no analogues for rapid and safe cartilage reshaping. For better penetration of radiation optical clearing agents (OCAs) can be applied. In present work, the effect of low-osmolality agent iohexol on costal cartilage is studied. Specifically, it is shown that ½ of total increase of optical transparency occurs in 20 minutes of immersion. Maximally, cartilage transparency on 1560 nm can be increased in 1.5 times. Injection of iohexol results in increased tissue hygroscopicity, lower drying rate and higher percentage of bound water. Effective diffusion coefficients of water liberation at 21°C are (5.3 ± 0.4) × 10 and (3.3 ± 0.1) × 10 cm /s for untreated and iohexol-modified tissue, respectively. Raman spectroscopy of irradiated iohexol solution reveals its photo and thermo-stability under clinically used IR laser energies up to 350 W/cm for exposure times of several seconds. At energies higher than 500 W/cm [Correction added on 5 September 2018, after first online publication: This unit has been changed] decomposition of iohexol occurs rapidly through formation of molecular iodine and fluorescent residue.

“…Analyzing the obtained effect for implants of different thickness we showed that well‐controlled heating through the whole thickness of an implant is crucial for the new shape stability . Simultaneously, the very local heating of cartilage by separate laser spots is needed to avoid thermal injury of matrix and cells . But the attempts to heat the deep tissue layers of thicker implants may cause the superficial burn and substantially disturb the safety of the procedure.…”

Section: Introductionmentioning

confidence: 99%

Controlling the near‐infrared transparency of costal cartilage by impregnation with clearing agents and magnetite nanoparticles

Alexandrovskaya

Sadovnikov

Sharov

et al. 2017

Penetration depth of near-infrared laser radiation to costal cartilage is controlled by the tissue absorption and scattering, and it is the critical parameter to provide the relaxation of mechanical stress throughout the whole thickness of cartilage implant. To enhance the penetration for the laser radiation on 1.56 μm, the optical clearing solutions of glycerol and fructose of various concentrations are tested. The effective and reversible tissue clearance was achieved. However, the increasing absorption of radiation should be concerned: 5°C-8°C increase of tissue temperature was detected. Laser parameters used for stress relaxation in cartilage should be optimized when applying optical clearing agents. To concentrate the absorption in the superficial tissue layers, magnetite nanoparticle (NP) dispersions with the mean size 95 ± 5 nm and concentration 3.9 ± 1.1 × 10 particles/mL are applied. The significant increase in the tissue heating rate was observed along with the decrease in its transparency. Using NPs the respective laser power can be decreased, allowing us to obtain the working temperature locally with reduced thermal effect on the surrounding tissue.