Publications by authors named "S E Avetisov"

215 Publications

[State of corneal nerve fibers after laser-assisted in situ keratomileusis].

Vestn Oftalmol 2021 ;137(3):39-48

Research Institute of Eye Disease, Moscow, Russia.

Purpose: To assess the state of corneal nerve fibers (CNF) based on quantitative parameters after laser correction of myopia using LASIK.

Material And Methods: The study examined 141 eyes - 80 eyes with myopia and 61 emmetropic eyes. In 47 cases a microkeratome was used to form a corneal flap, and in 33 cases a femtosecond laser was used (LASIK and FemtoLASIK, respectively). Confocal microscopy was performed before, as well as 1, 3, and 6 months after correction. Objective analysis of CNF involved automatic calculation of the anisotropy () and symmetry () coefficients of CNF orientation in the Liner 1.2S software.

Results: Lower values of were revealed in myopia as compared to emmetropia. Regardless of the method of flap formation, no CNF could be detected in the central cornea 1 month after myopia correction. In all cases after FemtoLASIK and in 2 cases after LASIK, CNF in the central cornea were first visualized after 3 months, and after 6 months CNF could be detected in all cases. At a similar observation time, CNF were visualized both after LASIK and after FemtoLASIK in the superior and inferior peripheral portions of the cornea. Analysis of long-term postoperative changes in and revealed a decrease in the former and an increase in the latter.

Conclusion: Evaluation of the state of CNF after corneal refractive correction should take into account the initial changes in CNF in myopia that are possibly associated with an increase in axial eye length. A more dynamic restoration of innervation was noted in cases where the flap was formed with the femtosecond laser, which may be explained by the fact that the mechanism of tissue separation when using this type of coherent radiation is gentler. Considering the changes in the quantitative indicators characterizing the state of CNF, the question of «completeness» of the restored CNF as a result of reinnervation remains open.
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http://dx.doi.org/10.17116/oftalma202113703139DOI Listing
June 2021

[Results of a two-year clinical study of myopia control with bifocal defocus-inducing soft contact lenses].

Vestn Oftalmol 2021 ;137(3):5-12

National Myopia Institute, Moscow, Russia.

The development of methods for myopia control remains one of the most topical trends in modern ophthalmology. Optical approaches to myopia control employ the induction of peripheral myopic defocus, which can be done with the use of multifocal soft contact lenses (SCLs).

Purpose: To review the results of a two-year multicenter clinical study of myopia control with bifocal defocus-inducing SCLs.

Material And Methods: The two-year study enrolled 100 patients aged 8 to 16 years who had mild or moderate bilateral myopia with spherical equivalent of (-)0.25 to (-)5.75 D. Based on the degree of myopia and the method of its correction, patients were divided into two main and two control groups. Multifocal SCLs with +4.0 D add power and monofocal SCLs were used for myopia correction. The results were evaluated by the clinical data of refraction, axial length and state of accommodation. The observation times were 3, 6, 12, 18 and 24 months.

Results: After 12 months of bifocal SCLs usage, signs of stabilization of myopia progression were identified in 72 and 73.5% of subjects of both main groups, after 24 months - in 54 and 79.5% of subjects, respectively. Statistically significant reduction in axial elongation amounting to 87-88% was also observed in patients using bifocal SCLs. A significant increase in positive relative accommodation (PRA) was observed in all groups.

Conclusion: The study indicates the effectiveness of bifocal soft contact lenses in slowing the progression of mild and moderate myopia.
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http://dx.doi.org/10.17116/oftalma20211370315DOI Listing
June 2021

[Radial keratotomy: history and current state].

Authors:
S E Avetisov

Vestn Oftalmol 2021 ;137(2):123-131

Research Institute of Eye Diseases, Moscow, Russia.

Results of clinical use of the radial keratotomy (RK) surgery are presented in the format of a lecture and a summary. The analysis encompasses the mechanism of changes in corneal refraction, immediate intra- and postoperative complications, so-called secondary symptoms and long-term effects (addition of various pathological processes, influence of corneal changes on the results of diagnostic tests and treatment methods) of the surgery.
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http://dx.doi.org/10.17116/oftalma2021137021123DOI Listing
April 2021

[Assessment of age-related changes in lens capsule biomechanics using atomic force microscopy].

Vestn Oftalmol 2021 ;137(1):28-34

Institute for Regenerative Medicine of the Sechenov University, Moscow, Russia.

Studies devoted to the assessment of lens capsule biomechanics can be divided into fundamental and applied. The former are oriented towards analysis of various indicators characterizing elasticity of the capsule as a basal membrane that maintains and changes the shape of the lens, and the latter deal with widespread introduction of modern microinvasive methods of phaco surgery into clinical practice.

Purpose: To assess age-related changes in lens capsule biomechanics based on atomic force microscopy (AFM).

Material And Methods: The study included 50 central fragments of the anterior capsule of the human lens obtained intraoperatively during ultrasonic phacoemulsification by continuous circular capsulorhexis. The measurements were carried out in the Fast Force Volume (FFV) mode. The force curves were processed in the Nanoscope Analysis software (Bruker, USA) using the Hertz model that allows calculating the Young's modulus of the capsule sample based on the dependence of the force on the puncture depth.

Results: There was no statistically significant difference in the «stiffness» of the inner and outer surfaces before and after removal of the subcapsular epithelium (=0.25). In all cases, the inner surface of the capsule turned out to be «harder» than the outer one. In this case, the ratio of Young's modulus of the inner and outer surfaces has a significant dependence on age (<0.001). With an increase in age from 50 to 90 years, this ratio decreased from ~7 to ~1.5. This was due to a simultaneous change in Young's modulus of the opposite nature: an increase in the stiffness of the outer surface and its decrease in the inner one.

Conclusion: It is possible to assess lens capsule biomechanics using AFM if the subcapsular epithelium is present. In this case, the objects of study are the areas of the capsule free of epithelium, and the epithelial cells themselves can be used to identify the inner surface of the capsule. Regardless of age, the stiffness of the inner surface of the anterior lens capsule significantly exceeds that of the outer surface.
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http://dx.doi.org/10.17116/oftalma202113701128DOI Listing
February 2021

Biomineralization of Trabecular Meshwork in Open-Angle Glaucoma.

Dokl Biochem Biophys 2020 Nov 25;495(1):307-310. Epub 2020 Dec 25.

Research Institute of Eye Diseases, Moscow, Russia.

A new form of open-angle glaucoma has been identified, in which calcification and silicification of the trabecular meshwork is a potentially significant component of outflow obstruction. It is noted that the mineralization of this area is promoted by various disturbances in the acid-base balance in the tissue. The role of melanosomal enzymes in the initiation of the formation of mineral calcium phosphate in trabecular tissue in open-angle glaucoma is considered.
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http://dx.doi.org/10.1134/S1607672920060083DOI Listing
November 2020
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