The process of manufacturing a matrix-gel biochip is modelled by means of laser fused deposition of a layer of polymer microparticles, containing a sensitive peptide element, onto a glass substrate. The limits of acceptable ranges and the optimal values of laser parameters, at which the melting of the polymer coating occurs without damaging the sensitive elements of the biochip, are theoretically determined. The results of the experiments on laser fused deposition of a layer of microparticles having the size 3-4 mu m confirm the conservation of the functions of the biological complexes at optimal irradiation regimes. The parameters of the laser impact affecting the possible minimal separation between the zones of laser fused deposition are investigated. The essential role of heat conductivity and thermoplasticity of the polymer in increasing the size of the melted droplet is demonstrated. Using the laser radiation with the wavelength 532 nm focused into a spot with the diameter 6 mu m (the laser pulse duration being 10 ms) the laser fused deposition density of 110000 spots per 1 cm(2) is achieved. The maximal estimated density of laser fused deposition for the studied system amounts to 250000 spots per 1 cm(2).

The manufacturing of biochips by heating a multicomponent layer of polymeric microparticles that contain sensitive elements is simulated. Heating is performed up to the stage of polymer shell melting without damage to the sensitive elements. The corresponding thresholds of laser parameters (radiation power density) are detected. The preservation of biological complex functionality under these parameters is experimentally shown.

Optical transmission and ablation mechanisms in the secondary cataract films under the impact of 1.06-mu m laser radiation are studied. The comparison of incident and transmitted (paraxial) radiation power at different values of the power density is carried out for two types of the eye lens capsule tissue (hard and soft) possessing different optical and mechanical properties. It is found that the effective attenuation coefficient for soft films is almost five times as large as that for the hard ones. The obtained measurement data on the transparency variation in the process of laser action allow the temperature evaluation and the determination of dominant mechanism of laser ablation, as well as the development of recommendations, providing the prevention or reduction of possible side effects. The obtained results can be used to optimise the regimes of laser impact in the process of the opacified lens capsule removal.

PURPOSE: Investigation of nondestructive influence of pulse-periodic laser emission (wave length 1.56 μm) on microstructure changes in human sclera (in vitro), it's hydropermeability in rabbit sclera (in vivo) and also hypotensive effect in treatment of resistant form of primary open-angled glaucoma in preliminary clinical trials. METHODS: We used two types of ophthalmological laser devises: 1) diode laser ophthalmocoagulator «LAHTA-МILON» (St-Petersburg, Russia) with wave length 1.56 mμ, 2) diode laser ophthalmocoagulator OcuLight SLx («Iridex», USA) with wave length 0.83 mμ. Morphological investigation was carried out in 16 rabbit eyes by means of semifine section method and atom force microscopy (NаnoScope Veeco Instruments, cantilever Nanosensors ATEC-NC-50, USA). Clinical trials included 76 patients (76 eyes) aged 27-91 years (32 males and 44 females), who were divided into two groups depending on the used technology - traditional or original. RESULTS: Our study revealed laser-induced restructuring of the sclera and formation of submicron pores in collagen tissue promoting local increase of hydropermeability. The first-time presented clinical results prove the proposed laser technology capable of producing a stable hypotensive effect for the 12-month follow-up period. CONCLUSION: The new technology based on the thermomechanical effect of laser radiation on the microporous structure of the human sclera has an advantage over the acclaimed technologies of laser cyclodestruction applied in the treatment of resistant forms open-angled glaucoma.

The optical properties of costal cartilage and their variation under the action of laser radiation with the wavelength are studied. The laser action regime corresponds to that used for changing the cartilage shape. The dynamics of the passed scattered laser radiation was studied by means of the optical fibre system, and the optical properties of the cartilage tissue (on the basis of Monte Carlo modelling of light propagation) – using the setup with two integrating spheres. Under the influence of radiation, the characteristics of which corresponded to those used for the cartilage shape correction, no essential changes in the optical parameters were found. The results obtained in the course of studying the dynamics of optical signals in the process of costal cartilage irradiation can be used for developing control systems, providing the safety and efficiency of laser medical technologies.

Optical properties of cornea and sclera of the eye and their alterations under the effect of 1.56-μm laser radiation are studied. The laser settings corresponded to the laser treatment regimens used (1) to correct the shape of the cornea and change the refraction of the eye and (2) to improve the hydraulic permeability of the sclera in glaucoma cases. A fiber-optical system to investigate the dynamics of the reflected and transmitted scattered laser radiation and a setup with a double integrating sphere to determine the optical properties of the ocular tissues on the basis of the Monte-Carlo simulation of the propagation of light was used. When the radiation characteristics corresponded to the treatment regimens for correcting the shape of the cornea, no noticeable changes were detected in its optical properties. When irradiating the sclera in conditions corresponding to the treatment regimens for improving its hydraulic permeability, the optical characteristics of the tissue showed definite changes. The results obtained as to the dynamics of the optical signals during the course of laser irradiation of the cornea and sclera create prerequisites for designing test systems to be used with novel medical laser techniques for correcting visual abnormalities.

Background and ObjectivesPores in the sclera are a candidate pathway for aqueous transport and therefore can be utilized to decrease the intraocular pressure (IOP) in glaucomatous eyes. Since pore formation is a well-known mechanism for stress relaxation in solids, laser-induced creation of pores in cartilage increases hydraulic permeability and promotes tissue regeneration. The aim of this paper is to demonstrate the thermo-mechanical effect of non-destructive laser irradiation on microstructural changes in sclera, in particular pore formation, resulting in substantial increase of water permeability of eye tissues that can be a novel approach to normalize the IOP.Materials and MethodsExperiments were performed ex vivo on eight eyes of four mini-pigs and in vivo on eight eyes of four rabbits using pulse repetitive laser radiation of 1.56 mu m in wavelength. Twenty laser spots of 0.6mm in diameter with laser settings (power 0.9W, pulse duration of 200milliseconds, pulse repetition rate of 2Hz) resulting in substantial increase of sclera hydraulic permeability were applied on the sclera at 1-2mm from the eye limb. Sclera and underlying structures (choroid and ciliary body) of the rabbits' eyes were examined histologically in 1 and 45 days after laser irradiation, atomic force microscope (AFM) was applied before and after laser irradiation.ResultsHistological and AFM examinations have clearly recognized laser-assisted stable structural alterations: rarefication of the collagen structure in the laser irradiated zone and formation of sub-micron pores. Laser-induced alterations in the structure of ciliary bodies were small in size and mainly reversible. We have proposed a possible mechanism of the arising pores stabilization due to formation of small stable gas bubbles in sclera tissue.ConclusionsIt 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. Lasers Surg. Med. 46:46-53, 2014. (c) 2013 Wiley Periodicals, Inc.

Increase of scleral water permeability due to formation of porous structure after exposure of pulsed periodic radiation of erbium-glass optical fiber laser with wave length 1,56 pm was demonstrated in experimental study of cadaver human eyes in vitro and eyes of experimental animals (rabbits) in vivo. Simultaneous complex laser exposure of pars plana and ciliary processes results in summation of morphological changes that provide decrease of aqueous humor secretion, uveal drainage and extension of suprachoroid space. A base for new noninvasive technology of nondestructive laser exposure in glaucoma treatment is established.