[Transpupillary laser photocoagulation of ocular fundus: history, the present, and the future]. / Transpupillyarnaya lazernaya fotokoagulyatsiya tkanei glaznogo dna: proshloe, nastoyashchee i budushchee.

The present review covers the use of chorioretinal photocoagulation, which is now a popular treatment for many diseases of the ocular fundus. The review includes a detailed 50-year history of the technology with account to both Russian and foreign achievements. The current state of the field is shown through Russian and foreign literature data. A particular emphasis is placed on subthreshold, pattern, and navigated techniques. Breakthrough solutions, such as optoacoustic monitoring, that ensure high precision of the procedure, maximum saving of tissues, and high therapeutic effectiveness are described.

[Results of infrared diode laser application for iris reconstruction in cases of pupillary deformity and displacement in pseudophakic eyes].

The article studies application possibilities and potency of near infrared coagulative radiation of a diode laser for correction of postoperative iris defects followed by pupillary deformities and displacement. It is found that the use of near infrared diode laser radiation at 0.810 microm enables visual improvement through pupil enlargement or its shift to the optical centre. The use of the wavelength specified does not cause severe atrophic or cosmetic changes in the iris.

Experimental study on the mechanical strain of corneal collagen.

Currently, investigations of biomechanical properties of the fibrous tunic are becoming even more topical, especially for diagnosis of corneal ectatic disease, as well as correct interpretation of intraocular pressure (IOP) parameters, particularly in patients with prior surgery on cornea. The study principle is based on the ability of substances to change optical anisotropy depending on mechanical strain applied to them. An experimental set-up was constructed which allows assessment of polarization degree of light which is emitted during luminescence of strained collagen. The study was performed on 18 corneoscleral discs of chinchilla rabbit eyes at 15 and 50mm Hg pressure, among them in 6 cases before and after making radial incisions, and in 6 cases before and after conducting the mechanical cornea abrasions that were asymmetrical by depth until reaching the local zone of iatrogenic keratectasia. Corneal collagen mechanical strain mappings were formed on 3 experimental models (intact cornea, cornea post radial keratotomy and keratectasia) under intra-chamber pressure of 15 and 50mm Hg. Corneal collagen mechanical strain is evenly allocated in the intact cornea. After radial keratotomy the main mechanical loading was concentrated over the middle part of corneal periphery, particularly in the bottom of keratotomic incisions. The increased intra-chamber pressure made the strain rise in those models. Upon cornea abrasion the main straining is distributed within the thinning zone, and the increase of intra-chamber pressure only increases the load over residual stroma. A new principle of corneal biomechanical properties investigation based on assessment of degree of light polarization emitted during luminescence of strained collagen, has been proposed and experimentally tested.

[Comparative experimental morphological study of efficacy and safety of near-infrared and visible wave-length laser iridoplasty].

The features of interaction of laser radiation with iris tissue were determined in experimental morphological study. The potential of laser irradiation with different spectral characteristics for pupil ectopia correction is estimated. The results of morphometry showed effectiveness of near-infrared diode laser radiation, that presents as an iris contraction in coagulation region with minimal tissue trauma. This fact allows us to propose a near-infrared diode laser radiation as a treatment option for correction of pupil form and location. Alternatively visible wave-length laser showed to be less effective and more traumatic.

[Fibrous tunic biomechanics and biometric indicies. Report 1. The impact of axial length, thickness and corneal curvature].

The degree of impact of several fibrous tunic biomechanical parameters on biomechanical indices was studied using multifactor correlation analysis. In patients with "normal" cornea corneal thickness was found to be the most significant factor influencing corneal hysteresis, corneal resistance factor, elasticity coefficient and elasticity rise, hence values of corneal biomechanical properties prevail over all other biomechanical indices studied in this work. However influence of significant changes in scleral biomechanics (e. g. in high myopia) on these factors (especially corneal hysteresis and elasticity rise) can not be excluded.

[Fibrous tunic biomechanics and biometric indicies. Report 2. The impact of topographic features in keratoconus].

The potential relation of biomechanical indices with topographic features in keratoconus was studied using multifactor correlation analysis. Topographic features in keratoconus were found to have influence on biomechanical measurements in the central zone of the cornea. If the zone of ectasia is distant from the central part of the cornea the central biomechanics can remain normal. Elasticity coefficient was found to be the most sensitive and keratoconus topography-dependent biomechanical index compared with other biomechanical parameters studied in this work.

[Test device for estimation of viscoelactic properties of biological tissues].

The results of development of test device for estimation of viscoelactic properties of biological tussues are presented. Special software provides opportunity to make a graph representing intension within tested material. A high correlation between acoustic density and lens viscoelactic properties was found when isolated lenses after extracapsular cataract extraction were tested.

[Polaroid oscopic diagnosis of early corneal dystrophic changes in dry eye syndrome].

The current methods widely used in ophthalmology to examine patients to diagnose the dry eye syndrome and to trace the course of a process are invasive. Both the Norn test using stains and the Schirmer test with the filter paper strips being inserted are stimuli that affect the rate of tear generation, which misrepresents the data obtainable. The developed procedures for examining the eye in polarized light permit one to considerably reduce the invasiveness of patient examination. The study indicated the high efficiency and diagnostic value of the proposed procedures in the examination of patients with the dry eye syndrome. Polarization filters available in the standard kit of up-to-date slit lamps make it possible to use the proposed procedures without any modification of ophthalmological equipment in wide clinical practice.

[A new principle in the investigation of the biomechanical properties of the cornea (a preliminary communication)].

A new principle in the determination of mechanical stress distribution in the cornea is proposed on the basis of estimation of the polarization of light emitted by luminescence of strained collagen. It has been found, collagen fiber stress is inversely proportional to corneal stress on the intact cornea of a rabbit, and absolute values are determined by intraocular pressure values. After applying keratotomic incisions, the stress distribution map changes, at the same time, the major stress falls on the residual thickness of the stroma at the bottom of a keratotomic scar and close to this area and the central corneal region is subject to the least pressure.

[Investigation of the biomechanical properties of the cornea by bidirectional applanation: new approaches to interpreting the results].

This study deals with the biomechanical properties of the cornea, which is essential in solving different problems of clinical ophthalmology, specifically in predicting the potential complications of keratorefraction operations, in early diagnosing keratoconus, and interpreting the measurements of intraocular pressure. The investigations confirmed the efficiency of using bidirectional applanation of the cornea to define its strength characteristics. A procedure has been also developed to estimate the elasticity coefficient which reflects the elastic properties of the cornea irrespective of intraocular pressure values.

[Experimental (in vivo) study of the capacities of use of radachlorine (chlorine E-6) for photodynamic therapy in ophthalmology].

To study the capacities of ophthalmological application of the photosensitizer Radachlorine (0.35% solution for intravenous injection), the authors carried out a series of in vivo experiments on rabbits. They studied the time parameters of distribution of the agent in the chorioretinal complex and the reaction of newly formed vessels to photodynamic therapy. Radiation of a diode laser at a wavelength of 0.662 microm was used to stimulate the photosensitizer. A video micro-camera adapted to the ocular of a split lamp was applied to fluorescence fixation. Superficial corneal vascularization was used as a model of the neovascular membrane in response to the application of a non-penetrating silk suture. The findings suggest that photodynamic therapy using Radachlorine is safe and effective in treating ocular tissue neovascularization.