[Influence of corneal curvature and peripheral thickness on tonometry readings]. / Vliyanie krivizny i perifericheskoi tolshchiny rogovitsy na rezul'tat tonometrii.

PURPOSE: This study investigates the influence of peripheral corneal thickness (PCT) and its curvature on tonometry readings. MATERIAL AND METHODS: The study included 49 patients (49 eyes) who were indicated for glaucoma surgery. Using bidirectional applanation tonometry, the following parameters were obtained: IOPcc, IOPg - intraocular pressure (IOP) corrected for corneal compensation, taken as the most reliable indicator; IOP converted to Goldmann measurement, taken as the result of applanation tonometry, ΔIOP (IOPcc-IOPg), CH and CRF (corneal hysteresis and corneal resistance factor). During corneal topography, the corneal thickness was studied in the center, PCT at 1.5; 2, 3, 4 and 5 mm from the center in four meridians, as well as ΔPCT (PCT 3 mm - PCT 1.5 mm), the curvature of the anterior and posterior surfaces of the cornea and the depth of the anterior chamber. Aberrometry was used to obtain refractometry data and the curvature of the anterior surface of the cornea. The influence of the studied parameters on ΔIOP was evaluated. RESULTS: ΔIOP correlated with CRF (r= -0.652), CH (r= -0.873), central corneal thickness (r= -0.293), PCT at all distances except 5 mm (r= -0.297; -0.287; -0.302; -0.303), with the strong and weak meridians of the anterior surface of the cornea (r=0.328; r=0.315), with the strong and weak meridians of the posterior surface, as well as the average curvature of the posterior surface (r=0.307; r=0.332; r=0.328). After step-by-step selection of the above parameters for creating a linear regression model for ΔIOP calculation, CH, CRF and PCT1.5mm remained in the model. The model describes ΔIOP with high accuracy (R2=0.974). CONCLUSION: Biomechanical parameters of the cornea are the leading factor of applanation tonometry error. Individual linear dimensions of the cornea (thickness, curvature) have a lesser effect.

[Effect of refractive surgery on Maklakov tonometry results]. / Vliyanie keratorefraktsionnoi khirurgii na rezul'taty tonometrii po Maklakovu.

PURPOSE: The study investigates the influence of changes in keratometric parameters after refractive surgery on the results of Maklakov tonometry. MATERIAL AND METHODS: The study examined a total of 61 people (121 eyes). The patients were divided into a control group with no history of surgery (16 people, 31 eyes), a LASIK group (13 people, 26 eyes), a femtosecond-assisted LASIK (FS-LASIK) group (16 people, 32 eyes), and a photorefractive keratectomy (PRK) group (16 people, 32 eyes). The patients underwent standard examination, keratometry (Km), Maklakov tonometry with a 10 g weight, and elastotonometry with 5, 7.5, and 15 g weights. RESULTS: In the LASIK group, the indentation diameter with 5 and 7.5 g weights correlated with Km in the central and near-paracentral zone (r=0.3-0.5). Tonometry with a 10 g weight did not correlate with anything. Tonometry with a 15 g weight inversely correlated with Km in the paracentral points (4 mm) of the strong meridian (r= -0.5 ... -0.7). In the FS-LASIK group, a significant inverse correlation with Km was observed only for the indentation diameter with a 10 g weight in the paracentral (3-4 mm) zone (r= -0.4 ... -0.5). In the PRK group, weak (r<0.4) correlations were found between Km and the indentation diameter of the 7.5 and 10 g weights for the central zone (1-2 mm). No significant correlations were found for 5 and 15 g weights.In the control group, there were practically no correlations for 5 and 7.5 g weights. The indentation diameter of the 10 g weight evenly correlated with Km at all points (r= -0.38 ... -0.60), the indentation of the 15 g weight correlated mainly with the curvature of the horizontal meridian (r= -0.37 ... -0.49). CONCLUSION: Tonometry readings with the 10 g weight are the most dependent on Km in different groups, and the readings with the 5 g weight are the least dependent. LASIK is characterized by the largest scatter of dependencies for weights of different masses, FS-LASIK - by the smallest. Tonometry readings with the 5 g weight correlated with Km only in the LASIK group, and this was the only direct correlation. Considering the inverse nature of most correlations, higher Km may be associated with an overestimation of tonometry results, and lower Km - with its underestimation.

[Possibilities of physiotherapy in glaucomatous optic neuropathy after glaucoma surgery]. / Vozmozhnosti fizioterapevticheskoi stimulyatsii pri glaukomnoi opticheskoi neiropatii posle antiglaukomnykh operatsii.

The current primary approach to the therapeutic and surgical management of glaucoma is limited to lowering intraocular pressure (IOP). While normalization of IOP stabilizes some functional parameters, there is still potential for further restoration of lost visual function in the post-operative period while maintaining the "therapeutic window". Neuroprotection refers to the modification of retinal ganglion cells and the neuronal microenvironment to promote their survival and function. Numerous studies have identified effective neuroprotective methods for glaucoma; however, their implementation into clinical practice remains a significant challenge. This review presents the most clinically significant treatment strategies, as well as the latest therapeutic advances in physiotherapy.

[The effect of body position on the results of central and paracentral rebound tonometry]. / Vliyanie polozheniya tela na rezul'taty tochechnoi kontaktnoi tonometrii v tsentre i na periferii rogovitsy.

PURPOSE: This study analyzes the fluctuations of intraocular pressure (IOP) and clarifies the error of paracentral rebound tonometry associated with change in body position. MATERIAL AND METHODS: The study included 45 healthy volunteers aged 25.4±2.1 years. First we performed rebound tonometry in the sitting position in the center of the cornea and 3-4 mm from the temporal and nasal sides (Icare-c, Icare-n, Icare-t, respectively) and bidirectional applanation tonometry (IOPcc - corneal compensated, IOPg - Goldmann tonometry). Then we measured Icare-c, Icare-n, Icare-t in the supine position, and after 5 minutes repeated Icare-c in the supine position. After this, we measured Icare-c, IOPcc and IOPg in the sitting position. RESULTS AND DISCUSSION: Initial IOPcc and IOPg were 4.6±2.8 and 14.8±2.8 mm Hg. Initial Icare-c, Icare-t, and Icare-n measurements amounted to 15.0±1.9, 15.7±1.5 and 16.3±1.3 mm Hg; in the supine position the measurements were 16.4±2.1, 17.2±1.7 and 17.1±1.9 mm Hg. Paracentral measurements differed from Icare-c in both sitting and supine positions; only between Icare-t and Icare-n measured in the supine position there were no significant differences. The results of Icare-c, Icare-t, and Icare-n in body position change were comparable. Icare-c measured after 5 minutes in the supine position increased up to 16.6±2.4 mm Hg. Final IOPcc and IOPg did not differ from the initial measurements. Final Icare-c was lower than the initial result by 0.8±0.2 mm Hg, and lower than both supine Icare-c measurements by 2.1±0.2 and 2.6±0.2 mm Hg. CONCLUSION: Paracentral rebound tonometry findings exceed those of rebound tonometry in central cornea, but in body position change the alteration of measurements in the same points on the cornea are comparable. In the supine position IOP increases on average by 1.0-1.5 mm Hg compared to the sitting position.

[On refraction shift after trabeculectomy]. / K voprosu ob izmeneniyakh refraktsii posle trabekulektomii.

PURPOSE: To determine the factors affecting the shift of refraction after trabeculectomy. MATERIAL AND METHODS: The study included 42 patients who were examined prior to trabeculectomy and at the following timepoints: 1 week, 1 month and 3 months after surgery. Examination included tonometry with assessment of corneal biomechanical properties, keratorefractometry with vector analysis, and biometry. The obtained data was processed for regression analysis and to find the possible correlations. RESULTS: All significant correlations between the measured parameters only occur on week 1. Postoperative spherical component of refraction (sphere) correlates negatively both with preoperative axial length (AL) and anterior chamber depth (ACD) (r=-0.699 and r=-0.458, p<0.05) and postoperative AL and ACD (r= -0.767 and r= -0.415, p<0.011). Dependence of sphere on AL is also expressed as a regression model. The magnitude of AL change depends on the magnitude of intraocular pressure (IOP) change (r=0.729, p<0.0001) and correlates negatively with postoperative IOP (r=-0.454, p=0.009) and baseline corneal hysteresis (CH; r= -0.482, p=0.009). Dependence of AL on IOP is also expressed as a regression model. The magnitudes of sphere and cylinder shifts correlate negatively with each other (r=-0.416, p=0.038). Keratometry reveals that the overall cylinder value correlates with the corneal cylinder, and so do the magnitudes of their shifts (r=0.589 and r=0.574, p<0.0001). Dependence of corneal hysteresis on IOP is expressed as a regression model; however, neither tonometric nor biomechanical corneal properties correlate with refraction. CONCLUSIONS: Sphere correlates negatively with AL and ACD. In turn, AL is related to the reduction in IOP. This dependence is likely the most important one for the refraction shift after trabeculectomy. No correlations were found for the change of astigmatism.

[Iris shape change and risk of anterior chamber angle closure]. / Izmenenie formy raduzhki i risk zakrytiya ugla perednei kamery.

Potential obstruction of the anterior chamber angle by iris root is a key factor of the pathogenesis of angle-closure glaucoma. Development and adoption of ultrasound biomicroscopy and optical coherence tomography in clinical practice have significantly expanded the capabilities of studying the structures of the anterior eye segment in terms of angle closure risk factors through improving visualization depth and quality of examination, including different variants of iris structure and potential changes of its shape in mydriasis. The article reviews various studies dedicated to the progression of primary angle-closure glaucoma and its dependence on the biometric parameters of the eye and changes in pupil size.

[Continuous anti-glaucoma drug therapy as a risk factor of dry eye]. / Dlitel'naia terapiia protivoglaukomnymi preparatami kak faktor riska razvitiia sindroma sukhogo glaza.

A preservative is a mandatory component of the eye drops designed to prevent microbial contamination in an opened bottle. Most of the preservative agents are either detergents, or oxidants; the most widely used and well-studied preservative - benzalkonium chloride - is a detergent. Due to regular usage of glaucoma eye drops, cytotoxic impact of the preservatives on anterior eye surface is considered the principal cause of its pathology, which leads to a decrease in quality of life. The high cost of preservative-free pharmacological forms and the complicated process of developing new preservatives make the usage of eye drops with minimal required concentration of preservative agent and a moistening component a good compromise. The most commonly utilized moistening component is polyvinyl alcohol - synthetic polymeric hydrogel, which is also used in artificial tears and bioengineering.

[Refractive shift after glaucoma surgery]. / Izmeneniia refraktsii posle antiglaukomnoi khirurgii.

Filtering glaucoma surgery can affect certain biometric features of the eye: it can change the axial length and anterior chamber depth, while redistribution of mechanical tensions in the fibrous tunic can alter the shape of the cornea. Among these changes that affect refraction, reshaping of corneal curvature is the principle one. Contrary to the expectations, and in contrast to changes associated with cataract surgery, glaucoma surgery led to decrease in vertical corneal radius (steepening) and development of the with-the-rule astigmatism. A number of studies helped reveal the features of corneal astigmatism that appears after glaucoma surgery: its power, duration, possibility of horizontal meridian flattening, influence of topical cytostatic drugs and drainage devices, etc. Potential reasons of astigmatism development were suggested: conjunctival incisions and sutures in the limbal area, quantity and strength of flap sutures, intraocular pressure level, shift of fistula edges, tissue contraction after cauterization, etc. The key role in pathogenesis of the refractive shift due to change of corneal curvature may belong to particularities of wound healing in the cornea and sclera: healing in sclera is similar to one of connective tissue - its ultrastructure undergoes aging process followed by change of rigidity. At the same time, the main reason for the development of corneal astigmatism after glaucoma surgery remains unclear.

[XEN-45 Gel Stent implant in glaucoma treatment]. / Mikroshunt XEN-45 dlia lecheniia glaukomy.

The XEN-45 drainage implant is a hypotensive device made of hydrophilic gelatin and stabilized by glutaraldehyde. The implant is designed for modern Microinvasive Glaucoma Surgery (MIGS). Being installed ab interno, the stent drains aqueous fluid from the anterior chamber into the subconjunctival space. According to indications, XEN-45 can be used in treatment of primary open angle glaucoma, pseudoexfoliation or pigment glaucoma with uncompensated intraocular pressure amid maximum tolerated hypotensive therapy, and refractory glaucoma including cases with history of unsuccessful surgery. The implant can also be effectively used in combination with phacoemulsification. The article describes the structure and implantation process of the XEN drainage and reviews existing clinical trials on its effectiveness. The article also presents results on hypotensive efficacy of the implant, as well as characteristics and complications of postoperative management.

[Optical coherence tomography for examination of glaucoma surgery site]. / Vozmozhnosti opticheskoi kogerentnoi tomografii v issledovanii zony khirurgicheskogo vmeshatel'stva antiglaukomnoi operatsii.

The article reviews the results of using optical coherence tomography (OCT) - a non-invasive non-contact examination method for obtaining a tomographic slice image of the site of glaucoma surgery. The method helped reveal the functional relationships between the newly created outflow pathways and various parameters of the filtering bleb such as its linear dimensions, wall structure, presence of microcysts, position of drainage, etc. Due to its high resolution and noninvasiveness, OCT can be reliably used to examine the structure of aqueous outflow pathways in different postoperative periods with accuracy close to morphometric. The amount of data that had been obtained with the method has allowed the creation of new classifications and clarification of OCT-relevant prognostic signs for glaucoma surgery site.

[The role of fixed dose combinations in the treatment of primary open-angle glaucoma]. / Rol' fiksirovannykh kombinatsii lekarstvennykh sredstv v lechenii otkrytougol'noi glaukomy.

A great number of patients with primary open-angle glaucoma require combination therapy with several hypotensive drugs of different pharmacological groups to efficiently compensate the intraocular pressure (IOP) and prevent further development of glaucoma. Although glaucoma treatment usually starts with monotherapy, several preparations administered simultaneously have stronger hypotensive effect further increased by their additive action. However, the increased frequency of instillations may lead to drug washout and decreased patient compliance. Fixed dose combinations (FDCs) are a pharmacological form of eye drops that combines two or more active drugs in a single dosage form. The frequency of FDCs administration does not exceed two per day, which is convenient for long-term application and helps improve patient compliance. FDCs tolerability tends to be higher than that of simultaneous instillations of separate monotherapy drugs, while the hypotensive in clinical trials is comparable, in some real practice trials is superior. A review of existing studies showed that FDCs are superior to monotherapy in terms of cost-effectiveness. The use of FDCs was found to be beneficial for glaucoma treatment from the viewpoints of both reaching the target IOP for preserving visual functions in glaucoma patients, and minimizing the long-term treatment costs.

[Influence of cataract phacoemulsification on eye hydrodynamics in patients with prior trabeculectomy]. / Vliianie fakokhirurgii na gidrodinamiku glaza posle predshestvuiushchei sinustrabekuléktomii.

At present, phacoemulsification and trabeculectomy are the most widespread surgery methods in cataract and glaucoma treatment, generally recognized as the gold standard. Among elderly patients, comorbid glaucoma and cataract are extremely prevalent, so the order of the two surgeries and the time interval between them are pivotal choices when planning treatment strategy. The reason for it is that almost any eye surgery is considered a risk factor for long-term trabeculectomy effectiveness. In attempts to solve this problem, numerous studies have been conducted on the impact of cataract surgery on filtration bleb scarring. The problem of determining the time interval between surgeries, as well as other treatment nuances, remains relevant despite the long history of research and publications. Some results are cited as general recommendations on treatment tactics (increasing the time interval between operations, using antimetabolite and anti-inflammatory therapy, minimizing intraoperative traumatism). However, currently there are no specific recommendations for one of the most important factors - the time interval between cataract extraction and trabeculectomy.

[Hypotensive efficacy of bimatoprost in monotherapy of primary open-angle glaucoma]. / Gipotenzivnaia éffektivnost' bimatoprosta v monoterapii pervichnoi otkrytougol'noi glaukomy.

PURPOSE: To study the effectiveness of monotherapy with bimatoprost in patients with decompensated intraocular pressure (IOP). MATERIAL AND METHODS: 90 patients (132 eyes) with stage I-II glaucoma and decompensated IOP previously treated with timolol, latanoprost and travoprost were included in the study. Average IOP at the beginning of the study was 25.4±2.5 mmHg. All patients had their hypotensive medications substituted by bimatoprost. The patients were examined during the initial appointment, as well as after 4 and 12 weeks. RESULTS: IOP decrease was highest in the group of patients who had been treated with timolol: initially IOP was 26.2±1.8 mmHg, after 4 weeks - 21.0±2.2 mmHg, after 12 weeks - 20.8±1.9 mmHg (p<0.001). The initial IOP of patients who had been treated with latanoprost was 24.8±2.9 mmHg, 21.8±2.4 mmHg after 4 weeks, and 21.6±2.3 mmHg after 12 weeks (p<0.001). Patients who had been treated with travoprost had 25.6±2.2 mmHg initially, 23.0±2.5 mmHg after 4 weeks, and 23.2±2.6 mmHg after 12 weeks (p<0.001). By the end of the study IOP has decreased by 5.4, 3.2 and 2.4 mmHg in the groups of patients who had been treated with timolol, latanoprost and travoprost, respectively. CONCLUSION: Bimatoprost can be used as monotherapy if another hypotensive drug in monotherapy is insufficient for IOP compensation.