PURPOSE: There are two primary aims of this study:

1. To perform a comparative chemical analysis of aqueous humour (AH), scleral tissue, and trabecular meshwork in patients with primary open-angle glaucoma (POAG).

2. To evaluate the tissue’s chemical composition at the different POAG stages and with in patients with pseudoexfoliation glaucoma (PEG).

METHODS: The concentration of certain chemical elements — carbon (C), nitrogen (N), oxygen (O), aluminum (Al), calcium (Ca), chlorine (Cl), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), silicon (Si), sulfur (S) — was determined in the dried AH residue, trabecular meshwork and sclera biopsy samples obtained from patients with POAG (stage I and II), patients with pseudoexfoliation glaucoma (PEG), and patients with POAG without pseudoexfoliation material (PEM). Samples were analyzed using a scanning electron microscope (SEM) EVO LS 10 (“Zeiss”,Germany). The chemical composition study was performed with an energy-dispersive spectrometer (EDS) Oxford-XMAX-50 (“Oxford”,UK) in a low-vacuum mode (70 Pa) with an accelerating voltage of 21.5 kV.

RESULTS: In the case of POAG (stage I and II) patients, there were significant differences in Cl distribution in dried AH residue and Si distribution in the trabecular meshwork. In the case of pseudoexfoliative glaucoma (PEG) and patients with POAG without PEM, there was a difference in the N distribution in dried AH residue, as well as Ca, Cl, and Na distribution in the trabecular meshwork. During scleral tissue comparative chemical analysis, no significant changes in studied elements’ concentration between patient groups were evident.

CONCLUSION: Changes between stage II of POAG and stage III of POAG patient groups may indicate that there is an increase in the electrolyte and acid-base imbalance associated with the progression of the disease. Differences in chemical elements distribution in patients with PEG and in patients with POAG without PEM result from the molecular structure of PEM. The tissue’s water and salt balance and molecular chemical composition alterations provide the following insights for future research in finding the optimal treatment method for patients with all stages and types of glaucoma.

PURPOSE: To determine the main risk factors of noncompliance in glaucoma patients with different disease duration according to patients’ opinion.

MATERIALS AND METHODS: An analytical, multi-center study was conducted based on a survey of 616 patients with different glaucoma duration. The survey was carried out by 43 doctors from 7 countries. Questionnaires of patients included four main groups of risk factors for noncompliance. The rating of factors was evaluated by the average score, which patients assigned to this factor. The significance of 32 selected factors for non-compliance was evaluated using a point system from 10 (maximum significant factor) to 1 (minimum significant factor).

Analysis program: Statistica 8.0 (StatSoft Inc.,USA).

RESULTS: Data analysis revealed the leading factors for non-compliance according to patients’ opinion. They were factors of behavioral compliance (75%): lack of motivation; a complex instillation regime, changing the common way of life; lack of contact with the doctor; low degree of disease awareness; old and senile age. According to the patients themselves, the first place was occupied by factors related directly to treatment (40%), namely: current employment and employment at work; the number of bottles and the complicated mode of instillations, changing the common way of life; cost of drugs; the presence of side effects.

CONCLUSION: The proportion of low-grade patients, according to the answers of the patients themselves, is 24.4%, medium-sized — 74.4% and high-grade — 1.2%. The average treatment adherence in glaucoma patients was lower than expected. Understanding the main factors for non-compliance helps developing measures to increase it. The role of the joint work of the doctor and patient, aimed at achieving a common goal — improving the quality of treatment, is very important.

PURPOSE: To study the parameters of the foveal avascular zone (FAZ) and its relationship with the functional, structural and hemodynamic macular indicators in patients with primary open-angle glaucoma (POAG) and type 2 diabetes mellitus.

MATERIALS AND METHODS: The study included 103 patients (161 eyes), who were divided into 3 groups: the 1st group — 58 eyes (31 patients) with 1st stage of POAG and diabetes; the 2nd group — 53 eyes (36 patients) with 1st stage of POAG; the 3rd group — 50 eyes (36 patients) with diabetes. The patients underwent a complete ophthalmological examination, including optical coherence tomography with angiography mode using a Cirrus 5000 Angioplex machine (“Carl Zeiss Meditec”). Functional, structural, hemodynamic parameters, FAZ area, FAZ perimeter, circularity index were evaluated.

RESULTS: The lowest functional indicators were noted in the group of patients with a combined course of POAG and diabetes (best corrected visual acuity (BCVA) 0.63±0.19, MD -4.01±1.52 dB, visual field index 94.69±3.09%) and structural indicators (RNFL 79.91±12.66 μm and GCL+IPL 66.33±15.39 μm), accompanied by a decline in blood density and perfusion (wiPD 28.87±9.08%, wiVD 13.15±3.19/mm), a decrease in FAZ area almost by 2 times (0.62±0.03 mm2), an increase in its perimeter to 3.54±1.57 mm. The circularity index was significantly lower in groups 1 and 3 (0.59±0.11 and 0.58±0.09, respectively) compared with the 2nd group (POAG): 0.66±0.1. The results of the correlation analysis showed a statistically significant inverse dependence of the area and perimeter of FAZ on all hemodynamic parameters.

CONCLUSION: The combined course of POAG and diabetes, even in the initial stages of the disease, is accompanied by pronounced structural changes, deterioration of hemodynamic parameters and impaired microcirculation of the macula. Dynamic monitoring of the area and perimeter of the avascular zone, the circularity index is important for the control and early diagnosis of macular microcirculation disorders, risk assessment and the rate of progression of optic neuropathy in patients with glaucoma.

PURPOSE: To assess the impact of trabeculectomy, Ex-PRESS shunt and Ahmed valve implantation on biometrical values of the eye.

METHODS: The study included 196 patients divided in

3 groups: trabeculectomy (TE) group (n=116), Ex-PRESS shunt (EXP) group (n=28) and Ahmed glaucoma valve (AGV) group (n=52). Each patient underwent optical biometry (keratometry, axial length, anterior chamber depth), autorefractometry (Topcon-8800) intraocular pressure (iCare) and standard ophthalmological examination prior to the surgery, 1 month and 6 months after. Preoperative and postsurgical data were compared to assess biometric values changes.

RESULTS: There was a mild decrease of mean keratometry 6 months after AGV implantation (from 44.08±1.06 to

43.94±1.21 D, p=0.023). On the contrary, TE increased corneal refractive power (from 44.39±1.13 to 44.55±1.09 D, p<0.001) 1 month after the surgery. There were no significant changes in EXP group. Steep meridian curvature increases by 0.28±0.59 D (p=0.002) 6 months after TE. EXP implantation induced flattening of weak corneal meridian (by 0.28±0.37 D 6 months after the surgery, p=0.003) as well as AGV group (decrease on 0.14±0.38 D, p=0.036). There were no significant changes in steep meridian axis in TE and EXP groups. However, AGV implantation leads to steep meridian axis bias from

88.6±50.5 to 71.4±48.9° (p=0.057). TE and EXP induced mild axial length (AL) reduction (by 0.09±0.19 mm, p<0.001 and by 0.08±0.1 mm, p<0.001 for groups respectively) 6 months after the surgery. AL shortening in AGV group was insignificant (by 0.08±0.4 mm 6 months after procedure). There was no significant difference in anterior chamber depth (ACD) before and after the surgery for all study groups.

CONCLUSION: Impact of glaucoma surgery on main biometrical values used to IOL power calculation (keratometry, AL, ACD) could lead to refractive errors after phacoemulsification. Thus, biometry for patients who require cataract extraction should be performed not earlier than 6 months after glaucoma surgery.

PURPOSE: To establish the hypotensive effectiveness of the appointment of monotherapy with prostaglandin analogues/prostamide as the «starting» therapy for clinic stages of primary open-angle glaucoma (POAG) and the feasibility of combining them with local carbonic anhydrase inhibitors to correct the treatment regimen if necessary.

METHODS: A multicenter analytical cohort sample scientific prospective dynamic study was conducted on 30 scientific and clinical bases in 4 countries from December

2019 to February 2020. The study included patients with primarily diagnosed glaucoma (different stages, except terminal stage) — 60 patients (60 eyes). The eyes with the most pronounced glaucoma changes were the main focus of the study. Gender distribution: male — 31 (51.7%), female — 29 (48.3%), average age — 64 years. POAG diagnosis was verified by static computer perimetry, intraocular pressure (IOP) values and morphometric data of the optic disc. Measurement of the central thickness of the cornea in the optical zone and the thickness of the retinal nerve fibre layer via оptical coherence tomography was additional. We studied the tonometric and pneumotonometric IOP at the day of glaucoma diagnosis verification, one day after, 14 and 30 days after the therapy start. Monotherapy with prostaglandin analogues was offered to all patients as starting therapy. Local carbonic anhydrase inhibitors were used as additive therapy if necessary. Treatment correction was carried out 14 days after the therapy start.

RESULTS: The average IOP in all stages was 27.5 [24; 31] mm Hg, and 2 weeks after the appointment of prostaglandin analogues, it decreased to 20 [19; 21] mm Hg. IOP decrease percentage amounted to 26.9% [33.3; 19.1] of the initial values. Optimal IOP has achieved in 46 of 60 patients (76.7%). These were mainly patients with an early stage of POAG. By the end of the second week of treatment, 14 patients (25%) needed additional hypotensive therapy using local carbonic anhydrase inhibitors. On day 30 without the use of additional therapy, IOP level reduced by 28.8% [33.3; 19.2], and in patients with combination therapy by 32.75% [41.9; 23.7].

CONCLUSION: This study confirmed the feasibility of using a differentiated («stepwise») approach to the treatment of patients with different clinical stages of first-time diagnosed POAG.

PURPOSE: To assess keratometric changes after trabeculectomy (TE), Ex-PRESS shunt (EXP) and Ahmed glaucoma valve (AGV) implantation.

METHODS: The study included 196 patients divided in 3 groups: TE group (n=116), EXP group (n=28) and AGV group (n=52). Each patient underwent keratometry (Topcon-8800) and corneal topography (Tomey RT-7000) proir to the surgery, 1 month and 6 months after intervention. Preoperative and postsurgical data were compared to assess keratometric values changes.

RESULTS: Corneal astigmatism (CA) magnitude increased by 0.3 D 6 months after TE and EXP. There was a significant correlation between CA magnitude and uncorrected visual acuity (UCVA) in TE and EXP groups (r=-0.497, p=0.002; r=-0.405, p=0.006, respectively). AGV implantation did not lead to significant changes in CA magnitude. Steep corneal meridian increased from 44.79±1.79 to 45.08±1.12 D  (p=0.002) 6 months after TE. EXP implantation decreased flat meridian from 44.28±1.01 to 44.0±1.09 D (p=0.002). There was a decrease of flat corneal meridian from 43.59±1.04 to 43.44±1.19 D (p=0.036), as well as a change of the steep meridian axis from 88.6±50.5 to 71.4±48.9 deg (p=0.057) in AGV group.

CONCLUSION: Decline of UCVA is associated with an increased CA magnitude after TE and EXP. Thus, patients should be informed that prescribing new spectacles or toric intraocular lens implantation due to upcoming phacoemulsification is a frequent perspective after these types of glaucoma procedures. Nevertheless, AGV implantation has no significant impact on CA magnitude and does not affect UCVA.

PURPOSE: To analyze pathological alterations of the parameters of the optic disc as well as peripapillar and macular zones of the retina in preperimetric glaucoma patients.

MATERIALS AND METHODS: 57 patients with preperimetric glaucoma (33 eyes) and control group (24 eyes) were examined. We used HRT and OCT methods and computer software to perform color-coding of all pathological parameters.

RESULTS: Pathologically similar parameters that showed different relations between HRT and OCT results were divided into 3 subgroups: a) with equivalent results according to both methods; b) with the advantage of HRT method; c) with the advantage of OCT method.

CONCLUSIONS: When examining the parameters of OD and attached retina, HRT and OCT methods complemented each other, which allowed a better understanding of the processes occurring in glaucoma.

The literature review dwells on the role of nicotinamide (vitamin B3) in providing neuroprotective and antioxidant protection of the retina in glaucoma optic neuropathy. It presents the data of foreign studies on its positive influence on the condition of retinal ganglion cells and axons of the optic nerve. There is a revival of interest to nicotinamide use in glaucoma in foreign literature of recent years. This is due to its active influence on metabolic processes. As a cofractor of enzymes, it is involved in cell metabolism, tissue respiration, gene expression, redox processes and the repair of deoxyribonucleic acid. Due to direct neuroprotection nicotinamide prevents and slows down the processes that cause apoptosis, such as ischemia, oxidative stress, inflammation, mitochondrial dysfunction, excitotoxicity, impaired axonal transport and loss of neurotrophins. In the central nervous system, vitamin B3 is recognized as a key mediator of the development and survival of neurons. It promotes the differentiation of nerve cells from embryonic stem cells into mature neurons, increases the synaptic plasticity of neurons and promotes the growth of axonal processes. It also shows significant anti-inflammatory, antioxidant and anti-apoptotic effects in various cells and tissues. Nicotinamide counteracts amyloid toxicity and the formation of reactive oxygen species, and its bioavailability plays a crucial role in normal functioning of neurons and in the prevention of neurodegeneration processes.

Particular attention is paid to the antioxidant and neuroprotective role of niacin, as well as its deficiency in neurodegenerative diseases, and other neuropathological conditions. Plasma nicotinamide deficiency was also detected in glaucoma. This allowes suggesting that nicotinamide supplements could be the future therapeutic strategy for glaucoma (as an adjunctive to antihypertensive therapy). It was found that oral administration of niacin has a pronounced neuroprotective effect, protects retinal ganglion cells in chronic ocular hypertension. Niacin consumption correlats with an improvement of vascular endothelium and an oxidative stress reduction. Thus, nicotinamide can be a valuable addition to the antihypertensive therapy of glaucoma and other neurodegenerative diseases, as well as conditions associated with aging.

Glaucoma is the leading cause of irreversible blindness worldwide. There are many varieties of glaucoma surgery. Among the complications of glaucoma surgery, an important place is occupied by the detachment of the choroid, which can develop both intraoperatively and in the postoperative period. In the CIS countries, prophylactic posterior trepanation of the sclera (PTS) is widespread in order to prevent ciliochoroid detachment. The results of recent clinical trials presented in this review demonstrate the lack of evidence for the implementation of PTS to prevent the development of choroid detachment. The implementation of this surgical intervention is justified in the postoperative period by the development of ciliochoroidal detachment in the absence of the effect of drug therapy.

This review summarizes the results of studies dedicated to analyzing the ocular surface condition and the patients’ quality of life after filtration surgery (mainly sinus trabeculectomy). Intraocular pressure is the only modifiable factor in the treatment of primary open-angle glaucoma (POAG). Usually POAG treatment starts with antihypertensive eye drops, the components and active substances of which can affect the ocular surface, and lead to iatrogenic dry eye syndrome (DES). The symptoms of DES impair the quality of life of glaucoma patients and reduce adherence to treatment. It is worth noting that advanced stages of the disease require surgical treatment, which also effects the ocular surface.