Olga V. Beznos

The purpose of the work was to study the effect of bandage scleroplasty (BSP) on the level of dopamine (DA) in the tear fluid and choroidal thickness (CT) in patients with high progressive myopia. Material and methods . Fifty patients (50 eyes) aged 13.1 ± 1.7 years were examined and divided into 3 groups: Group 1 — children with congenital myopia (spherical equivalent (SE) = 14.5 ± 3.4 D), Group 2 — with acquired myopia (SE = 8.3 ± 1.5 D); Group 3 (control) — with emmetropia and low hyperopia (SE = +0.25 ± 0.7 D). In addition to the routine examination, the children’s eye axial length (AL), choroidal thickness (CT) using the SLO/OCT Mirante multimodal platform (Nidek, Japan), and retinal light sensitivity (RLS) in the macular area using the MP-3 microperimeter (Nidek, Japan) were determined. Biochemical studies of tear fluid were also performed to determine the DA concentration before and 1 month after BSP. Results. In congenital myopia, DA after BSP decreases (by an average of 77 pg/mg protein), while in acquired myopia, it tends to increase (by an average of 20 pg/mg protein) with an increase in CT (by 13.0–20.3 %) in both groups. In patients with congenital myopia and initially low DA values, no normalization of hormone concentrations was observed after BSP, despite improved choroidal blood filling. However, with initially elevated DA levels, its concentration in tears decreased after BSP, accompanied by an increase in CT. Conclusion . BSP promotes an increase in CT in both acquired and congenital myopia. In congenital myopia, DA decreases after BSP, while in acquired myopia, it increases, which may be due to the preservation of retinal dopaminergic cells capable of synthesizing DA.

This review presents literature data indicating that tear fluid composition in keratoconus reflects the course of metabolic processes in this disease. In keratoconus, tear fluid shows changes in the activity of lysyl oxidase, prolidase, and heparanase, which participate in corneal structure remodeling. Tear fluid also shows enhanced free radical reactions, reduced intensity of energy processes, and disturbances in the protease-inhibitor balance and cytokine status. Despite the absence of visible signs of inflammation, tear fluid changes confirm the role of inflammation in the pathogenesis of keratoconus. Significant correlations between clinical study findings and tear levels of markers of these metabolic processes allow their use as biomarkers for detecting early stages of keratoconus, assessing disease severity, predicting progression, identifying therapeutic targets, and objectively evaluating treatment effectiveness, including after corneal cross-linking.

In patients with progressive myopia, there is an imbalance between the processes of lipid peroxidation and antioxidant protection, which is confirmed by changes in the level of hypoxia markers and the activity of the antioxidant enzyme superoxide dismutase (SOD) in the tear fluid (TF). Purpose: to study the SOD activity in the TF of patients with moderate and high progressive myopia after sclera-strengthening treatment. Material and methods. We examined 82 patients (82 eyes) aged 8 to 17 years with progressive myopia (ave 9.1 ± 0.3 D), divided into two main groups: in the 1st group (47 patients), minimally invasive scleroplasty (MIS) was performed using a biologically active graft, in the 2nd group (35 patients) — bandaging scleroplasty (BSP) according to the Snyder-Thompson technique using homoscleral graft. The control group consisted of 12 unoperated patients aged 7–13 years with low hyperopia (0.25 D to 1 D). At various times after MIS and BSP, SOD activity (by inhibition of quercetin autoxidation) and total protein concentration according to Lowry were determined. Results. SOD activity in the TF before surgery in patients of group 1 (32.0 ± 5.3 U/mg protein) and group 2 (24.7 ± 6.4 U/mg protein) was in generally significantly higher than in the control group (20.0 ± 3.2 U/mg protein). At the same time, in some patients with initially low SOD values, enzyme activity significantly increased 1 month after surgery (p < 0.01) and exceeded the control level by 4.3–5.2 times. In case of initially elevated SOD activity, on the contrary, the enzyme concentration significantly decreased (p < 0.01) — 3.5 times with BSP and 1.9 times with MIS. After 6 months, in patients of the MIS group with the initial level of SOD activity below the norm, the enzyme activity remained 2 times higher than normal values (p < 0.01). All other patients showed a decrease in SOD values to the control level, and in some cases below it. Conclusion. Sclero-strengthening treatment has a normalizing effect on SOD activity in the TF, which contributes to the correction of metabolic disorders caused by progressive myopia and confirms the importance of scleroplasty as a method activating bioregulation and normalizing oxidation-reduction processes in the eye tissues.

The purpose of the work was to study the activity of the acute phase inflammation protein alpha-2-macroglobulin (α2-MG) in the tear fluid (TF) of patients with different morphological variants of lacrimal gland tumors (LGT). Material and methods. The study included 33 patients with morphologically verified diagnosis of LGT. The control group (healthy individuals) was additionally recruited for comparative evaluation. TF was collected from both eyes before surgery using filter paper. The activity of α2-MG was determined by enzymatic method. Results. It was revealed that in epithelial tumors of the LG — pleomorphic adenoma and lacrimal gland carcinoma, there was an increase of α2-MG activity in the TF on the side of the lesion compared to the control group. At the same time, in 67 % (n = 4) of LG carcinoma cases there was a tendency to increase α2-MG activity also on the healthy side. In LG lymphomas, no significant differences from the norm in α2-MG activity in the TF both on the tumor side and on the healthy side could be detected. The α2-MG activity did not depend on the tumor volume and clinical features. In patients with LG carcinoma with a history of more than 10 months, high values of α2-MG activity in the TF on the contralateral healthy side were detected. Conclusion. For the first time we evaluated the activity of α2-MG protein in the TF and showed characteristic features in different morphologic variants of LGT. The search for biochemical markers in TF opens new opportunities for studying the pathogenesis of this category tumors, which may contribute to the development of personalized therapy. The obtained data allow to improve diagnostics of LGT and can be applied in clinical practice in the system of complex diagnostics at the stage of preoperative preparation.

The review is devoted to the changes in tear composition in the most widespread retinal disorders: diabetic retinopathy, age macular degeneration, retinopathy of prematurity, acute blood circulation disorders, vitreoretinal pathology and also in the experimental transplantation of induced pluripotent stem cells in the model of retinal pigment epithelium dystrophy. Despite the fact that retina and tear fluid are not in touch, there is a connection between the retinal state and tear fluid metabolism due to the common regulatory pathways. Tear composition display the local physiological changes in the eye even more than blood one. Correlation between concentration of certain metabolites in tears but not in blood and stage of the pathological process in retina was revealed. The review represents data about changes of a number of metabolites playing the key role in pathogenesis of retinal diseases — factors participating in the inflammation, angiogenesis, apoptosis, hemostasis, oxidative stress. The connection between these changes in tear composition and progress of the diseases are specially highlighted because it can be used for the early diagnostics and prediction of complications that is critical for the development of optimal therapeutic strategy. Tear fluid is recently often regarded as a body fluid used for the liquid biopsy that serves for the non-invasive investigation of pathological process. Easy and non-invasive way of tear fluid collection is one more preference of the method. Progress in the detection technology that allows using of very small samples makes it possible to introduce tear fluid analysis for biomarkers to the clinical practice.

The etiology of uveitis, choroid inflammation, is diverse, the disease is often recurrent, difficult to treat, and frequently results in disability at a young age. Studies investigating the tear fluid composition in uveitis have revealed promising biomarkers relevant for prognosis and treatment optimization. This review presents literature data on changes in the tear fluid content of proteins involved in local immune responses, intercellular interactions, proteolytic and free radical processes, nitric oxide metabolism, and other metabolic pathways in different forms of uveitis. The paper also demonstrates the significance of assessing these changes for prognosis and for a pathogenetically based, personalized treatment approach, and identifies specific alterations associated with different uveitis etiologies, offering insight into the mechanisms underlying this pathology.

Background. The global prevalence of dry eye disease (DED) continues to rise. Alterations in the composition of the tear film are a key factor in the development of this condition. In recent years, a growing body of evidence has emerged on the underlying mechanisms of DED pathogenesis, driven by increasing interest in tear fluid as a material for clinical and diagnostic studies. Purpose: to outline the main research directions concerning tear biomarkers of DED, as well as their role in prognosis, development of novel treatment approaches, and monitoring therapeutic effectiveness. Materials and methods. A literature search was conducted in PubMed for articles published from 2000 to 2024. The selection was carried out using a comprehensive sampling method with the following keywords: tear, dry eye disease, Sjögren’s syndrome, biomarkers, cytokines, oxidative stress, enzymes, extracellular vesicles, microRNAs, NETosis. A total of 60 articles were included in the review. Results. Literature data on tear composition changes in DED indicate the presence of both general inflammatory alterations and disease-specific features. The review summarizes findings on tear content changes involving oxidative stress markers, apoptosis-related factors, proteases and their inhibitors, cytokines, lipids, and nucleic acids. Tear hyperosmolarity is a hallmark of DED, contributing to the enhancement of inflammation, recruitment of neutrophils into the tear film, and the formation of neutrophil extracellular traps (NETs). Elevated levels of inflammation markers such as matrix metalloproteinase-9, lactoferrin, myeloperoxidase, and elastase are indicative of disease severity. Differences in tear composition between Sjögren-related and non-Sjögren DED have diagnostic potential. Furthermore, tear microRNAs show promise as severity markers and differential diagnostic tools in DED. Conclusion. Available literature convincingly demonstrates that tear components can serve as biomarkers for diagnostic, prognostic, and therapeutic monitoring purposes in dry eye disease. The investigation of DED biomarkers paves the way for personalized approaches to the treatment of this condition.

AIM: To investigate the role of proteolytic enzymes and their inhibitors in endogenous uveitis in children and develop new diagnostic criteria. MATERIAL AND METHODS: A total of 76 children (135 eyes) aged 3 to 17 years with uveitis were examined. All children underwent standard ophthalmological examination, posterior segment optical coherence tomography (OCT) was performed if required. Location, course, and activity of uveitis were assessed as per criteria developed by the International Uveitis Study Group. All patients underwent tear and serum biochemistry analysis, aqueous humor was tested if surgical treatment was required. Alpha-2-macroglobulin (α2-MG), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinases 1 (TIMP-1), urokinase-type plasminogen activator (uPA), and plasminogen (PG) levels were determined. Concentrations of α2-MG were measured by an enzymatic method using a specific substrate Nα-benzoyl-DL-arginine 4-nitroanilide (DL-BAPNA). MMP-9, TIMP-1, uPA, and PG levels were determined using an enzyme linked immunosorbent assay (ELISA). A total of 64 children (84.2%) were followed-up. The analysis included 1143 tear, 283 serum, and 79 aqueous humor samples. RESULTS: Active uveitis was found to be associated with activation of proteolytic enzymes and their inhibitors resulting in increased tear uPA levels, as well as increased uPA, MMP-9, and TIMP-1 levels in aqueous humor. Tear uPA level exceeds 80.7 pg/mL in active uveitis, ranges from 46.6 to 80.6 pg/mL in moderate/subactive disease, is less than or equal to 46.5 pg/mL in inactive phase/remission; it is one of the objective criteria to determine uveitis activity. In patients with panuveitis, tear MMP-9, PG, and α2-MG levels were higher compared to the children with anterior and peripheral uveitis. CONCLUSION: New data on the role of the proteolysis system in the pathogenesis of endogenous uveitis in children have been obtained. New criteria for assessing uveitis activity and severity have been established based on proteolytic enzymes and their inhibitors levels in tear fluid. The obtained results can be used to develop targeted therapy.

It is believed that in degenerative diseases of the retina, photostimulation by fractal dynamics signals activates neuroplasticity, thereby increasing the efficiency of visual rehabilitation. Previously, we showed a positive effect of fractal phototherapy (FF) on the electroretinogram (ERG) of healthy rabbits and demonstrated the safety of long-term photostimulation courses for the retina. The purpose of this work is to study the effect of FF on the functional activity and morphology of the retina in rabbits with a model of retinal pathology. Material and methods. We modelled an atrophy of retinal pigment epithelium (RPE) on both eyes of 50 rabbits. 30 days after the administration of bevacizumab, the animals were divided into two groups of 25 animals each. In the main group, photostimulation was performed using a device for FF, while in the control group incandescent lamps were used that create radiation of constant intensity. In both groups, 20-minute binocular light stimulation sessions were performed daily, five times a week. ERG and optical coherence tomography of the retina were performed before and after courses of treatment which lasted 1 week, 1 and 3 months. Results. Long-term courses of FF were shown to be safe for the morphology of the retina of animals with the RPE atrophy model. In all periods of observation, biochemical studies revealed no statistically significant changes in the content of norepinephrine and dopamine in the tear as compared with baseline values. In the main group, a slight positive effect of FF on rod and cone ERG was found after 5 FF sessions, while a significant increase in the amplitude of the transient and steady-state pattern-ERG (PERG), most pronounced after a 1-month FF course, was observed. Conclusions. A positive effect of FF on the functional activity of retinal ganglion cells (RGC) may suggest that prescribing a course of FF lasting up to 1 month (20 sessions) in diseases accompanied by a pathology of RGC is advisable, whereas for patients with a pathology of the macular region, such as AMD, an effective improvement in the activity of photoreceptors and bipolar cells could probably be achieved through a 1-week course of FF, conducted under the control of electroretinography.

Purpose: to develop a model of the early stage of retinal neurodegeneration via an intravitreal injection of the dopaminergic neurotoxin. Material and methods. The experiment was carried out on 20 Chinchilla rabbits. The experimental groups received intravitreal injection of 0.1 ml of 6-hydroxydopamine (6-OHDA) in NaCl 0.9 % with 0.5 % ascorbate, containing 0.25 or 0.5 mg 6-OHDA. The control group received injections of 0.1 ml of NaCl-ascorbate solution without neurotoxin. On the 7^th and the 14^th days after the injection, intraocular pressure (IOP), pupillary light reaction and ocular blood flow were estimated and the fundus was examined. On the 7^th day after an injection of 0.25 mg 6-OHDA, we used ELISA to measure dopamine concentration in retinal homogenates, while on the 14^th day after an injection of 0.5 mg 6-OHDA, the concentrations of dopamine, norepinephrine, TNF-a and endothelin-1 were measured by the same method. Results. On the 7^th day after a 0,25 mg injection of neurotoxine, we revealed a decrease of dopamine in the retina (0.043 ± 0.130 pg/mg protein compared with 0.10 ± 0,03 pg/mg protein in the controls, р < 0.01). On the 14^th day, dopamine and norepinephrine levels showed a fourfold increase (р < 0.05). An injection of 0.5 mg of 6-OHDA caused a threefold increase of dopamine (р < 0.05) and a fivefold increase of norepinephrine (р < 0.01) concentration in comparison with the controls. On the 14^th day, endotheline-1 level was 65 % higher than in the controls after a 0.25 mg 6-OHDA injection (р < 0.01) and 45 % higher after a 0,5 mg injection (рConclusion. A single intravitreal injection of dopaminergic neurotoxin 6-OHDA in the amount of 0.25 or 0.5 mg per eye leads to a neuroinflammation and vascular disorders, which are the main pathogenetic pathways of neurodegeneration. To model its early phase, the 0.25 mg dose is preferable as it causes less dramatic functional disorders. The latter model can be useful for the investigation of retinal neurodegeneration pathogenesis, the search for early diagnostic and prognostic markers thereof and the estimation of therapy effectiveness.