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Introduction: Elimination of extensive defects of the larynx and trachea by using musculoskeletal plastics without the use of supporting materials is not always sufficient. Laser modeling of cartilage tissue is a promising technique in modern medicine., Case Report: This article presents a new method for plastic closure of an extensive defect in the larynx and trachea with the help of costal auto-cartilage modeled by an erbium fiber laser with wavelength of 1.56 μm., Conclusions: The presented method allows us to restore the anatomical integrity of the respiratory tract at the final stage of surgical treatment of patients with chronic combined laryngeal and tracheal stenosis. Presented own clinical observation.

Moderate heating of collagenous tissues such as cartilage and cornea by infrared laser irradiation can produce biologically nondestructive structural rearrangements and relaxation of internal stresses resulting in the tissue reshaping. The reshaping results and eventual changes in optical and biological properties of the tissue strongly depend on the laser-irradiation regime. Here, a speckle-contrast technique based on monochromatic illumination of the tissue in combination with strain mapping by means of optical coherence elastography (OCE) is applied to reveal the interplay between the temperature and thermal stress fields producing tissue modifications. The speckle-based technique ensured en face visualization of cross correlation and contrast of speckle images, with evolving proportions between contributions of temperature increase and thermal-stresses determined by temperature gradients. The speckle-technique findings are corroborated by quantitative OCE-based depth-resolved imaging of irradiation-induced strain-evolution. The revealed relationships can be used for real-time control of the reshaping procedures (e.g., for laser shaping of cartilaginous implants in otolaryngology and maxillofacial surgery) and optimization of the laser-irradiation regimes to ensure the desired reshaping using lower and biologically safer temperatures. The figure of waterfall OCE-image demonstrates how the strain-rate maximum arising in the heating-beam center gradually splits and drifts towards the zones of maximal thermal stresses located at the temperature-profile slopes., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nowadays glaucoma is one of the leading causes of irreversible blindness worldwide. The main goal in preservation of vision in glaucoma patients is reducing intraocular pressure (IOP), which is considered the main controlled risk factor for progression of glaucomatous optic neuropathy. The article discusses the effectiveness and safety of various transscleral laser technologies in the treatment of glaucoma. Modern transscleral laser technologies that affect the uveoscleral drainage and scleral hydro-permeability are less traumatic and more gentle making them promising in the treatment of patients with early stages of glaucoma, and not only in terminal glaucoma with pain syndrome resistant to conventional treatment ("last resort surgery").

Moderate heating of such collagenous tissues as cornea and cartilages by infra-red laser (IR laser) irradiation is an emerging technology for nondestructive modification of the tissue shape and microstructure for a variety of applications in ophthalmology, otolaryngology and so on. Postirradiation high-resolution microscopic examination indicates the appearance of microscopic either spheroidal or crack-like narrow pores depending on the tissue type and irradiation regime. Such examinations usually require special tissue preparation (eg, staining, drying that affect microstructure themselves) and are mostly suitable for studying individual pores, whereas evaluation of their averaged parameters, especially in situ, is challenging. Here, we demonstrate the ability of optical coherence tomography (OCT) to visualize areas of pore initiation and evaluate their averaged properties by combining visualization of residual irradiation-induced tissue dilatation and evaluation of the accompanying Young-modulus reduction by OCT-based compressional elastography. We show that the averaged OCT-based data obtained in situ fairly well agree with the microscopic examination results. The results obtained develop the basis for effective and safe applications of novel nondestructive laser technologies of tissue modification in clinical practice. PICTURE: Elastographic OCT-based images of an excised rabbit eye cornea subjected to thermomechanical laser-assisted reshaping. Central panel shows resultant cumulative dilatation in cornea after moderate (~45-50°C) pulse-periodic heating by an IR laser together with distribution of the inverse Young modulus 1/E before (left) and after (right) IR irradiation. Significant modulus decrease in the center of irradiated region is caused by initiated micropores. Their parameters can be extracted by analyzing the elastographic images., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 -7 and (3.3 ± 0.1) × 10 -7 cm 2 /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 2 for exposure times of several seconds. At energies higher than 500 W/cm 2 [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., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The article describes a newly developed and tested diffractive optical element (DOE) that converts non-uniform radiation of the laser output into a homogeneous ring. The Gerchberg-Saxton algorithm is shown to be well suited for achieving annular intensity distribution. Testing this ring transducer on threshold-plasticity cornea demonstrated the reversibility of axisymmetric changes in the cornea. Atomic-Force microscopy of the area of maximum stresses in the corneal periphery showed no significant changes in the structure of the cornea when irradiated in the selected mode. Measurement of Young's modulus of the corneal surface areas after their irradiation also revealed no changes in the elastic properties, while examination of the corneal structure demonstrated the absence of significant structural changes in irradiated samples compared with intact ones.

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., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The review covers different aspects of the impact of femtosecond laser-assisted cataract surgery on the state of the macular zone of the retina. Literature search has revealed inconsistency of the published data and indicated the need for a more detailed study of this problem.

Background and Objective: Laser reshaping of cartilage is a prospective technique which can be applied for manufacturing the natural implants for otolaryngology and reconstructive surgery. Optical properties and optimal laser settings for laser reshaping of costal cartilage depend on its thickness, water content, and structural anisotropy of the tissue, in particular, the distinct orientation of collagen packing. The aim of the work is to study the effect of different collagen orientation, thickness, and drying of costal cartilage on its interaction with laser radiation., Materials and Methods: Costal cartilage was cut along and crosswise the distinct collagen orientation. The dried and normal cartilage was used for the comparative analysis. The collagen package was studied using atomic force microscopy. The dried tissue was analyzed with thermogravimetry-differential scanning calorimetry (TG-DSC) analysis to reveal the residual water content. The optical transmittance was measured for two wavelengths λ: 1,560 and 532 nm. The reshaping of cartilage of 1-3 mm in thickness was performed with infrared laser with λ = 1560 nm while, the radiation with λ = 532 nm was used to determine the location of the IR beam., Results: The transmittance of 532 nm radiation does not depend on collagen orientation and tissue drying. The IR radiation transmits better along the distinct collagen direction in dried cartilage while in normal cartilage the intensity of transmitted IR radiation increases intermittently passing crosswise and does not change dramatically with time along the collagen orientation., Conclusions: The effect of structural anisotropy of costal cartilage reveals itself in the increasing scattering of IR radiation with λ = 1,560 nm passing crosswise the collagen orientation when tissue water content is decreased. The radiation with λ = 1,560 nm is effective to perform the reshaping for cartilage of 1-3 mm in thickness; however, for 3 mm, the residual mechanical stress should be taken into account. Lasers Surg. Med. 48:887-892, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background and Objective: Magnetic nanoparticles with the ability to absorb laser radiation are the perspective agents for the early diagnostics and laser therapy of degenerative cartilage. The effect of starch stabilized magnetite nanoparticles (SSNPs) on the cartilage structure components has never been studied before. The aim of the work is to establish the Erbium:glass laser effect on costal and articular cartilage impregnated with SSNPs., Materials and Methods: Porcine articular and costal cartilage disks (2.0 mm in diameter and 1.5-2 mm in thickness) were impregnated with SSNPs and irradiated using a 1.56 μm laser in therapeutic laser setting. The one sample group underwent the second irradiation after the SSNPs impregnation. The samples were analyzed by the means of histology, histochemistry and transmission electron microscopy (TEM) to reveal the alterations of cells, glycosaminoglycans and collagen network., Results: The irradiated cartilage demonstrates the higher content of cell alterations than the intact one due to the heat and mechanical affection in the course of laser irradiation. However the alterations are localized at the areas near the irradiated surfaces and not dramatic. The impregnation of SSNPs does not cause any additional cell alterations. For both costal and articular cartilage the matrix alterations of irradiated samples are not critical: there is the slight decrease in acid proteoglycan content at the irradiated areas while the collagen network is not altered. Distribution and localization of impregnated SSNPs is described: agglomerates of 150-230 nm are observed located at the borders between matrix and cell lacunas of articular cartilage; SSNPs of 15-45 nm are found in the collagen network of costal cartilage., Conclusions: It was shown that SSNPs do not appreciably affect the structural components of both articular and costal cartilage and can be safely used for the laser diagnostics and therapy. The area of structural alterations is diffuse and local as the result of the mechanical and heat effect of laser impact. SSNPs reveal the areas of the structural alterations of cartilage matrix and give information about the size of the pores and defects., (© 2015 Wiley Periodicals, Inc.)