On the limiting power of set of knots generated by 1+1- and 2+1- braids

We estimate from above the set of knots, $\Omega(n,\mu)$, generated by closure of n-string 1+1- and 2+1-dimensional braids of irreducible length $\mu$ ($\mu>>1$) in the limit n>>1.Comment: 14 LaTeX pages, 2 PostScript figure

Etiopathogenesis of non-exudative age-related macular degeneration (literature review)

The article presents an overview of modern publications on epidemiology, risk factors, and the main links of the etiology and pathogenesis of age-related macular degeneration (AMD). The nonexudative or “dry” form of age-related macular degeneration is a multifactorial progressive pathological process caused by hereditary predisposition, general and local disorders of lipid metabolism, negative changes in  the blood supply to the eye, age-related destruction of the Bruch’s membrane and retinal pigment epithelium, the appearance of signs of local and systemic inflammation, the development of oxidative stress with the impact of toxic lipoperoxidation products on the structures of the posterior segment of the eye. Recent studies have discovered new ways of retinal pigment epithelial cell death in response to oxidative stress in AMD, in particular necroptosis, which, in addition to classical apoptosis, is considered the main mechanism of this process. It is noted that the development of AMD may be associated with an age-related decrease in the level of estrogen in women. The analysis of the data on the etiopathogenesis of age-related macular degeneration presented in the modern literature indicates the need for further research and generalization of local and general pathological processes developing in the dynamics of retinal visual function disorders by specialists of various scientific disciplines

Results of surgical treatment of ptosis of the upper eyelid by the dosed muscle-conjunctival resection of the upper cartilage

Blepharoptosis is an abnormally low position of the upper eyelid in relation to the eyeball due to its omission. The method of surgical treatment of blepharoptosis depends on the function of the levator.The aim. To analyze the results of surgical treatment of partial blepharoptosis of various etiology by the dosed muscle-conjunctival resection of the upper eyelid cartilage.Material and methods. We operated 78 patients (82 eyes) with blepharoptosis, among them with congenital blepharoptosis – 34 people (36 eyes), with acquired – 44 (46 eyes). The patients’ age was from 6 to 82 years.Inclusion criteria: the function of the upper eyelid levator – more than 5 mm, the width of the palpebral fissure – 3 mm or more.The patients underwent a dosed muscle-conjunctival resection of the upper eyelid cartilage in the period from 2018 to 2021. The follow-up period ranged from 2 months to 2 years.Results. Elimination of blepharoptosis was achieved in all patients. With congenital blepharoptosis, a good result was obtained in 33  people (91.7  %), satisfactory – in three patients (8.3 %), which was associated with the asymmetry of the palpebral fissure, for the correction of which these patients underwent additional intervention. In patients with acquired ptosis of the upper eyelid, a good result was achieved in 91.3 % of cases (42 eyes). One patient underwent repeated surgery due to hypocorrection and asymmetry of the palpebral fissure width after the first surgery.In all patients, the result remained stable throughout the observation period.Conclusion. The use of the method of dosed muscle-conjunctival resection of the upper eyelid cartilage in patients with partial ptosis of the upper eyelid and intact levator function made it possible to obtain a good cosmetic and functional result: with congenital blepharoptosis – in 91.7 % of cases, acquired ptosis of the upper eyelid – in 91.3 % patients

Regional features of the epidemiology of pterygium in the Republic of Bashkortostan

Background. Pterygium is ubiquitous and multifactorial; today, information on  the  prevalence of pterygium, risk factors, the relationship of its development with concomitant pathology and the type of life activity of patients in various regions of Russia is limited. All of the above led to the conduct of this epidemiological study in the Republic of Bashkortostan.The aim of the study: to study the prevalence of pterygium, as well as to identify the relationship of risk factors for its development with the type of life activity and concomitant diseases in the urban and rural population of the Republic of Bashkortostan.Methods. On the basis of the Ufa Research Institute of Eye Diseases, within the framework of the Ural Eye and Medical Study (UEMS) research project, a population study of people living in urban and rural regions of the Republic of Bashkortostan was carried out. The study involved 5899  people, including men – 43.7  % (2585  people), women – 56.3 % (3314 people), urban residents made 42.3 % (2491 people), rural – 57.7 % (3408 people).Results. As a result of our study, pterygium was diagnosed in 138 people (204 eyes – 2.3 %) (95% CI: 2.0–2.7 %). One-way analysis showed a higher prevalence of pterygium associated (p˂0.10) with a number of systemic and ophthalmic parameters. However, according to the results of multivariate analysis, it was revealed that the prevalence of pterygium was significantly associated with older age (p = 0.006), rural area of residence (p = 0.001) and low educational level (p = 0.03).Conclusion. The prevalence of pterygium in Republic of Bashkortostan according to the UEMS study was 2.3 %, or 23 people per 1000 population among people over 40 years old. The nature of the settlement influences the prevalence of pterygium in  the Republic of Bashkortostan. Pterygium was more common among older people among all respondents who took part in the study. In the study, pterygium was not a biomarker of general somatic diseases

Crosslinking of Thin Corneas: a Modern Vision of the Problem. Literature Review

Ultraviolet crosslinking is a pathogenetically oriented method of treating primary and secondary corneal ectasias that cause irregular astigmatism and visual impairment. Advanced stage of the disease, when the initial thickness of the cornea is below 400 mc, is a contraindication to the use of the standard «Dresden» protocol of the procedure. In such cases, it is possible to use modified UV crosslinking protocols. This article presents the modern crosslinking methods used for progressive keratoconus in advanced stages with a thin cornea. The presented methods are combined taking into account principled approaches – using additional tools and without them. Both approaches are based on a temporary artificial increase in the thickness of the cornea during the procedure in order to reduce the likelihood of damage to the deep layers of the cornea. The evolution of crosslinking protocols for thin corneas began with the use of hypoosmolar solutions that increase the thickness of the cornea to safe values. However, such an approach was not stable and the change in pachymetry parameters during the procedure created difficulties in its standardization. The use of different staff to increase the thickness of the cornea by providing an additional layer like a contact or biological lens seemed more encouraging. At the same time, the low permeability of these additional layers to oxygen, much needed for the UV crosslinking process of macromolecules, limited the overall effectiveness of the procedure. As a result of the progressive development of technologies and  the improvement of devices, the logical continuation of the trend of modifying the crosslinking protocol was the  introduction of an individual approach to customization of the protocol. The described modified protocols, taking into account the different principles of the surgical approach in ultraviolet radiation, set forth the results, evaluate their effectiveness and safety when applied to patients with a thin cornea

Implantation of the First IMT Macular Lens in Age-Related Macular Degeneration (Literature Review)

This review presents the characteristics and results of clinical studies of patients with age-related macular degeneration implanted with the developed for this purpose first macular IOL – intraocular macular telescope (IMT). This lens was designed specifically for patients with the most severe or terminal form of age-related macular degeneration and is designed for monocular implantation to provide central vision while maintaining peripheral vision of the paired eye, which is important for maintaining the balance and orientation of patients. This device allows patients to see both in dynamic and static situations in the near, intermediate and far ranges. The disadvantages of this lens are a decrease in the visual field and depth of focus (which excludes its bilateral implantation), the need for a large (10–12 mm) incision for implantation, which can cause an increase in corneal astigmatism and the risk of complications, in particular, the pupillary block with an increase in intraocular pressure. There are also difficulties in the study of the fundus after its implantation to assess the small changes in the macula or to identify possible postoperative complications after cataract surgery (macular oedema, etc.). Also after the implantation of this lens, there is need for special programs of visual rehabilitation. The patient’s commitment to the rehabilitation measures for the adaptation of the central visual field of the operated eye with the peripheral vision of the second eye is crucial for success of the IMT macular telescope implantation procedure

The prevalence of cataract surgery and the assessment of postoperative visual function in the population of the Republic of Bashkortostan

Purpose. Studying the prevalence and functional results of cataract surgery and factors that negatively affect postoperative visual functions in the population of the R epublic of Bashkortostan.Material and methods. The study was carried out on the basis of a pilot descriptive population study – Ural Eye and Medical Study (UEMS), conducted on the basis of the Ufa Research Institute of Eye Diseases. This analysis included 5 885 people aged 40 and over with data on performing cataract surgery. Poor visual outcome after cataract surgery was defined with uncorrected visual acuity below 0.3. Statistical data analysis was performed using the IBM SPSS Statistics application package.Results. The prevalence of cataract surgery was 6.1% (95% confidence interval (95% CI) 5.5–6.8%). A higher frequency of operations was associated with the age factor (odds ratio – OR 1.13, 95% CI 1.11– 1.15%, p<0.001), male gender (OR 1.92, 95% CI 1.43–2.59, p=0.003), urban living (OR 1.37, 95% CI 1.04–1.80, p=0.02) and widowhood (OR 1.57, 95% CI 1.13–2.17, p=0.006). Low visual results after cataract surgery, considering the maximum postoperative correction, were found in 16.1% of cases (81 eyes). The main reasons for the low postoperative outcome: refractive error (40.4%), macular degeneration (18.5%), glaucoma (16.0%), posterior capsule opacification (13.6%) and diabetic retinopathy (12.3%).Conclusion. The obtained results of good postoperative uncorrected visual acuity amounted to 73.1% and turned out to be quite close to international standards (80%). The main reasons for the low visual results of cataract surgery were refractive error and age-related macular degeneration

On the Epidemiology of Diabetic Retinopathy in the Republic of Bashkortostan

Aim. To study of the prevalence of diabetes and diabetic retinopathy in the Republic of Bashkortostan among people over 40 years of age, depending on the stage of the disease, gender and the nature of the settlement of the respondents. Materials and methods. A population-based study “Ural Eye and Medical Study” on the basis of the Ufa Research Institute of Eye Diseases covered 5899 people, of whom 2581 (43.7 %) were men, 3318 (52.3 %) were women. There were 2501 (42.3 %) urban residents, 3398 (59.7 %) rural residents. Statistical data analysis was performed using the IBM SPSS Statistic application package.Results. According to the study, diabetes was observed in 687 people, among them – 221 (32.2 %) men, 466 (67.8 %) women; urban residents – 378 (55.0 %) people, rural – 309 (45.0 %) people. The prevalence of diabetes is 11.6 %. Diabetic retinopathy was observed in 102 people (27 men – 26.5 %, and 75 women – 73.5 %), urban residents – 60 (58.8 %), rural – 42 (41.2 %). The prevalence of diabetic retinopathy among the entire study population was 2.1 %, or 14.8 % in the diabetic population. Conclusions. The prevalence of diabetes in the Republic of Bashkortostan according to the results of the Ural Eye and Medical Study was 11.6 % among people over 40 years old. The prevalence of diabetic retinopathy in the general population of the republic was 2.1 %, and in the population with diabetes it was 14.8 %, which is, in general, less than the global average

Comparative characteristics of the outcomes of the use of multidirectional intravitreal pharmacotherapy in the treatment of diabetic macular edema

Purpose. To conduct a comparative analysis of the effectiveness of intravitreal injection of dexamethasone-containing implant and aflibercept in macular edema in patients with diabetes mellitus.Material and methods. The study involved 80 patients (80 eyes) with macular edema. The group 1 included 38 patients (38 eyes) who underwent a single intravitreal injection of dexamethasone-containing biodegradable implant «Ozurdex» in a dose of 0.7 mg according to the standard technique. In the group 2, 42 patients (42 eyes) received 5 loading doses of aflibercept with an interval of one month. All patients underwent monthly spectral optical coherence tomography (OCT) of the macular area, as well as visometry and tonometry during the observation period.Results. One month after intravitreal injection of the studied drugs in both groups, no inflammatory reactions were detected in any case. According to OCT data, cystic edema of the macular area with a tendency to decrease the thickness in the fovea was preserved. After treatment with aflibercept, the average retinal thickness in the macula was 186.4±15.1 μm, and visual acuity averaged 0.48±0.05 in 85.7% of patients. During therapy with intravitreal injection of Ozurdex, an increase in visual acuity was noted in 89.4% of patients.Conclusion. This study found that intravitreal pharmacotherapy with an angiogenesis blocker and a dexamethasone implant in patients with diabetic macular edema are comparable in its effectiveness – 85.7 and 89.4% respectively. If systematic anti-angiogenesis therapy is not possible for a number of reasons, it is advisable to use a prolonged dexamethasone implant

Intravitreal Dexamethasone Implant for the Treatment of Patient with Resistant to Anti-VEGF Diabetic Macular Edema

Purpose. To evaluate the effectiveness of intravitreal injection of biodegradable intravitreal implant containing dexamethasone (Ozurdex) in patients with resistant diabetic macular edema (DME).Material and methods. The study was conducted of 24 patients with diabetic macular edema resistant to therapy with angiogenesis inhibitors (3-5 intravitreal injections without a positive structural and functional result) on the background of compensated type 2 diabetes mellitus. A biodegradable intravitreal implant containing dexamethasone (Ozurdex) was injected once according to standard method at a dose of 0.7 mg. The follow-up period was 6 months.Results. According to optical coherence tomography of the macular area, within 6 months after intravitreal injection of Ozurdex implant, the retinal thickness in the fovea decreased on average from 558.4 ± 25.1 μm to 188.3 ± 18.4 μm, with partial restoration of the foveolar cavity. The maximum corrected visual acuity increased on average from 0,04±0,01 to 0,3±0,09, intraocular pressure did not exceed 18.0 mm Hg.Conclusion. If the anti-angiogenic therapy of DME is ineffective, the use of the biodegradable intravitreal implant containing dexamethasone (Ozurdex) is considered as an effective treatment method that provides a significant and stable (prolonged) improvement of the structural and functional parameters of the eye in 86,6% cases