Microstructural changes in sclera under thermo‐mechanical effect of 1.56 µm laser radiation increasing transscleral humor outflow

Abstract

It is shown, for the first time, that thermo-mechanical effect of pulse repetitive laser irradiation results in pores formation in sclera. That can be a basis of a novel, safe, and effective technique for IOP normalization due to enhancing of uveoscleral outflow under non-destructive laser irradiation of the sclera.

Hybrid optoacoustic and ultrasound biomicroscopy monitors’ laser-induced tissue modifications and magnetite nanoparticle impregnation

“…Ten laser spots of 0.6 mm in diameter, instantaneous power of 0.9 W, pulse duration of 200 ms, and pulse repetition rate of 2 Hz were applied on the sclera at a distance of approximately 1-2 mm from the eye limb. As previously reported, this particular laser setting provided the thermo-mechanical effect necessary for efficient formation of pores, which resulted in a substantial increase of hydraulic permeability in the sclera [4]. This unique effect was further employed for a new type of safe and effective intraocular pressure (IOP) normalization technique relying on the enhancement of uveoscleral outflow under nondestructive laser irradiation of the sclera [4].…”

“…By imaging tissues impregnated with NP of specific size distribution, one can target for early diagnostics of arthritis and other cartilage-related diseases which otherwise cannot be manifested today using MRI and other conventional imaging methods. It was recently established that laser-induced formation of pores in the sclera may serve as a basis for new approaches toward IOP normalization in glaucoma [4], however, no monitoring approach currently exists that can deliver an efficient feedback necessary for determining settings for optimal pore formation in IOP normalization procedures. The hybrid OA and US microscopy was able to visualize laser-induced formation of pores in the eye sclera, which can be potentially used to dynamically adjust the laser irradiation settings in order to prevent undesirable modification of the sclera structure.…”

“…Yet, safety and efficacy of laser modification technologies rely on efficient feedback control systems to accurately monitor the changes in tissue structure. To this end, laser-induced structural alterations have been mainly studied ex-vivo using conventional microscopic techniques applied to thin specimen, including histological methods [3], atomic force microscopy and electron microscopy [4,5]. Various non-destructive techniques, including light scattering measurements [5,6], optical coherence tomography (OCT) [7], and ultrasound imaging [8,9], have been also applied to study laser-treated tissues.…”

“…In the context of laser treatments, ultrasoundbased imaging might further become a promising candidate for monitoring of laserinduced formation of submicron size pores in cartilage matrix, which has been recently established as one of the factors promoting regeneration of cartilaginous tissues [3]. Similarly, formation of gaseous pores in laser-treated sclera allows substantially increasing its water permeability, serving as a basis for new types of glaucoma therapies [4]. By means of a optoacoustic imaging approach, which uses intense short-duration laser pulses to induce ultrasonic responses in deep tissues layers [10], a real-time feedback capability during laser treatments was recently showcased, yet only reported for monitoring of destructive laser ablation procedures [11].…”

Interplay of temperature, thermal‐stresses and strains in laser‐assisted modification of collagenous tissues: Speckle‐contrast and OCT‐based studies

“…Laser treatment of tissues is a rapidly developing field of biophotonics and medical physics in general. Biologically, nondestructive laser‐induced modification of several types of collagenous tissues, such as cartilaginous tissue , sclera and cornea, is a perspective branch of this field. For example, the laser‐induced temperature and thermal‐stress fields allow for changing the cartilaginous sample shape, which can be used for manufacturing allo‐ and autoimplants.…”