[Factors affecting the hypotensive effect of selective laser trabeculoplasty in primary open-angle glaucoma]

PURPOSE

This study analyzes the influence of various factors on the hypotensive effect of selective laser trabeculoplasty (SLT) in patients with primary open-angle glaucoma (POAG).

MATERIAL AND METHODS

A retrospective study of the SLT effect was performed in 582 patients (756 eyes; mean age - 71.9±9.5 years) with POAG stages I-III. The level of intraocular pressure (IOP) decrease was assessed at 1 day, 1, 3, 6, and 12 months after SLT. The relationship between the hypotensive effect and age, gender, glaucoma stage, initial IOP level, number and type of instilled drugs, presence of intraocular lenses, and the surgeon performing the intervention were analyzed.

RESULTS

In the entire sample, the hypotensive effect of SLT after 1 day was 4.1±3.4 mm Hg, after 1, 3, 6, and 12 months - 3.7±4.8; 3.5±3.8; 3.1±3.4 and 2.3±3.8 mm Hg, respectively. The hypotensive effect of SLT was most dependent on the preoperative IOP level (R>0.64, p<0.05). No significant correlation was found between the hypotensive effect and the stage of POAG, gender, age, number of hypotensive drugs, phakia/aphakia, and the surgeon. A weaker hypotensive effect of SLT was found in eyes receiving monotherapy with α2-adrenoceptor agonists (p<0.03) and a combination of four drugs (p<0.02).

CONCLUSION

SLT is an effective method of additional IOP reduction in POAG at any stage and with any hypotensive regimen. At the same time, the results of its use in real clinical practice indicate the need for more careful IOP control after the procedure, especially in eyes with POAG stage III, as well as in eyes without hypotensive therapy and on the maximum drop regimen.

[Multimodal topographically oriented approach to the study of full-thickness macular holes]

PURPOSE

This article studies the relationship between structural changes according to the findings of optical coherence tomography (OCT) and OCT angiography (OCTA), microperimetry (MP), multifocal electroretinography (mfERG) parameters in topographically corresponding areas of the macular region in idiopathic full-thickness macular holes (FTMH).

MATERIAL AND METHODS

OCT, OCTA, MP and mfERG were performed in 14 eyes with FTMH stages I-IV according to Gass. In 13 points at a distance of 0-2.5°, 2.5-5.0°, and 5.0-10.0° from the fixation point, the light sensitivity (LS), amplitude and latency of the P1 component were compared with the size of the hole, the area of cystic changes (CC) at the level of the inner nuclear layer (INL) and the outer plexiform layer and Henle fiber layer complex (OPL+HFL), vessel density in the superficial and deep capillary plexus (SCP and DCP).

RESULTS

LS and P1 component amplitude were significantly reduced at a distance of up to 5.0° from the fixation point. LS correlates with the apical and basal diameter of the hole (R> -0.53), the area of CC in the INL (R> -0.62) and the OPL+HFL complex (R> -0.55), the density of vessels in the SCP at a distance of up to 2.5° from the fixation point (R>0.51) and in the DCP at a distance of up to 5° from the fixation point (R>0.49). The P1 amplitude correlates with the basal diameter of the hole (R= -0.38), the area of CC in the INL and the OPL+HFL complex (R> -0.33) and vessel density in the SCP (R=0.37) at a distance of up to 2.5° from the fixation point, as well as vessel density in the DCP at a distance of up to 5° from the fixation point (R=0.47). Vessel density in the DCP is significantly lower in the presence of CC in the retina (p<0.001).

CONCLUSION

In FTMH, there is a relationship between bioelectrical activity and LS, and structural disorders, capillary perfusion in different layers of the retina. A multimodal topographically oriented approach allows studying the relationship between structural and functional parameters in individual points of the retina and can be used in monitoring of FTMH after surgical treatment.

[Direct assessment of changes in biomechanical properties of the cornea after ReLEx SMILE and FemtoLASIK surgeries]

The aim of this study was to evaluate corneal biomechanical properties in myopic patients after ReLEx SMILE and FemtoLASIK surgeries using the Corvis ST analyzer.

MATERIAL AND METHODS

The SMILE group comprised 23 patients (46 eyes) with spherical refraction -3.8±1.8 diopters (D), the FemtoLASIK group included 18 patients (36 eyes) with spherical refraction -3.5±1.3 D. Analysis of the biomechanical properties of the cornea was carried out using the CORVIS ST device (Oculus, Germany) before and seven days after corneal refractive surgery.

RESULTS

In the SMILE group, with intraoperative decrease in corneal thickness of 91.43±19.43 µm, a significant increase in the following parameters was observed: deformation coefficient (DA ratio; p=0.0001), peak distance (PD; p=0.02) and inverse concave radius (ICR; p=0.003); a decrease in the stiffness parameter at first applanation (SP-A1; p=0.0001), Corvis biomechanical index (CBI; p=0.0001), intraocular pressure (IOP; p=0.001). In the FemtoLASIK group, with intraoperative decrease in corneal thickness of 75.33±32.3 µm, we observed a significant increase in DA ratio (p=0.0002), PD (p=0.04), ICR (p=0.0002), a decrease in SP-A1 (p<0.0001), IOP values (p=0.0003). In comparison with the FemtoLASIK group, the deformation amplitude DA changed significantly less in the SMILE group (p=0.04). In the FemtoLASIK group, in comparison with the SMILE group, the DA ratio (p=0.0009) and SP-A1 (p=0.0003) significantly increased. Intraoperative corneal thickness change correlates with ICR both in SMILE (R=0.52) and in FemtoLASIK (R=0.65).

CONCLUSION

Corneal biomechanical properties determined with CORVIS ST in eyes with mild to moderate myopia change to a lesser extent after ReLEx SMILE compared to FemtoLASIK.

[Comparative assessment of the accuracy of toric intraocular lens calculations]

PURPOSE

To compare the accuracy of toric intraocular lens (IOL) calculations on three modern toric calculators.

MATERIAL AND METHODS

The study comprised 35 eyes of 35 patients who underwent phacoemulsification with toric IOL implantation (EnVista Toric). Residual postoperative refractive astigmatism was calculated on three calculators: EnVista Toric Calculator, ASSORT Toric IOL Calculator and the Kane formula. Prediction error for each calculator was determined using vector analysis.

RESULTS

The mean absolute deviation of predicted postoperative refractive astigmatism over actual astigmatism in diopters was distributed in the following way: 0.82±0.58, 0.70±0.67 and 0.72±0.76 using EnVista Toric Calculator, ASSORT Toric IOL Calculator and the Kane formula, respectively. Centroid prediction error was 0.08 (EnVista Toric Calculator), 0.06 (ASSORT) and 0.10 (Kane formula). There was a significantly smaller deviation using ASSORT and the Kane formula compared to the online calculator (p<0.05).

CONCLUSIONS

Toric calculators ASSORT Toric IOL Calculator and the Kane formula showed higher accuracy of toric IOL calculation than EnVista Toric Calculator.

Photodynamic Therapy in the Treatment of Choroidal Melanoma. Review

Choroidal melanoma is one of the most malignant tumors of the organ of vision, the development of which is associated with the risk of metastasis and the possibility of death, which indicates the relevance of the search and application of effective methods of treatment of this pathology. To date, in the treatment of choroidal melanoma, preference is given to organ-preserving methods aimed at achieving local control over the tumor. One of the promising organ-preserving techniques is photodynamic therapy, which is a treatment method based on the ability of a photosensitizer to absorb light, receive energy and interact with chemical substances, with the further development of toxic photodynamic reactions in target tissues, the occurrence of which is possible with the simultaneous presence of three components: a photosensitizer, light and oxygen. In our country, there is a number of studies devoted to the treatment of choroidal melanoma with PDT, basically presenting experimental research, pilot studies and demonstrating clinical cases. The purpose of this review is to summarize data on photodynamic therapy and the use of this technique in the treatment of choroidal melanoma.

[Vortex vein varix (clinical observations)]

Varix of the vortex vein ampulla is a rare benign condition that has clinical similarities to more concerning choroidal lesions that pose a threat to vision, in particular choroidal melanoma. The article describes two clinical cases, one of which is unique due to the combination of bilateral lesion and the presence of multiple varices in one eye. A brief review of the literature on this condition is also provided.

[Preventive laser treatment of tractional symptomatic retinal flap tears: long-term outcomes]

Tractional flap tears are the main cause of the development of regmatogenic retinal detachment (RRD). The main immediate treatment method for it is laser retinal coagulation.

PURPOSE

Case monitoring of tractional symptomatic flap tears after laser treatment.

MATERIAL AND METHODS

From 2014 to 2019 we observed 119 patients (130 eyes) with peripheral flap (horseshoe) retinal tears in acute posterior vitreous detachment. Laser coagulation of the retina was performed using Navilas 577s (577 nm), OcuLight GL (532 nm). Laser retinotomy of horseshoe tear flap and dissection of overhanging vessels were performed using Nd:YAG-ultra Q Reflex laser (1064 nm) and controlled with RTVue XR Avanti.

RESULTS

At the initial examination before the preventive laser coagulation, the following conditions were found: regmatogenous retinal detachment (RRD) - 8 eyes (6.2%), partial hemophthalmus - 29 (22.3%), preretinal hemorrhage - 15 (11.5%), epiretinal membrane - 9 (6.9%), non-full-thickness macular retinal breaks - 6 (4.6%), peripheral changes: retinal holes - 16 (12.3%), tears with operculum - 5 (3.8%), retinal degenerations - 40 eyes (30.8%). Observation for 5 years after laser retinopexy revealed new pathological changes: flap tears - 13 (10.6%); holes - 9 (7.4%); tears with operculum - 5 (4.1%); vitreoretinal tuft - 6 (4.9%); RRD - 3 cases (2.5%). In 16 patients (16 eyes) with horseshoe tear and pronounced vitreoretinal traction, the flap retinotomy was performed, which eliminated the traction component and prevented the development of RRD.

CONCLUSION

Follow-up of tractional symptomatic flap tears for 5 years after preventive laser retinopexy revealed the appearance of retinal detachment in 2.5% of cases. Laser retinotomy of horseshoe tear after barrier retinopexy eliminated the traction component and helped prevent the development of RRD.

[Dome-shaped macula: features of differential diagnostics with clinical examples]

The phenomenon of dome-shaped macula (DSM) constitutes protrusion of membranes of the posterior pole of the eye toward the vitreous body due to local thickening of sclera layers. The phenomenon was detected using enhanced depth imaging optical coherence tomography (EDI-OCT). In uncomplicated forms of DSM, all layers of the retina are contiguous, but the setting of DSM can involve a number of pathological conditions causing decrease in vision. One of the most often described concurrent conditions in DSM is serous retinal detachment (SRD). Such complicated forms of DSM are often masked as a non-pigmented neoplasm of the choroid, in particular hemangioma (HC).

PURPOSE

To demonstrate the possibilities of differential diagnostics of DSM with HC using modern instrumental diagnostic methods.

MATERIAL AND METHODS

The study involved two clinical cases of patients with DSM and HC, who underwent comprehensive ophthalmological examination including EDI-OCT and OCT angiography, fluorescent angiography (FA), indocyanine-green angiography (ICG) and magnetic resonance imaging of brain and orbits (MRI).

RESULTS

The most simple and highly informative method for differential diagnostic of DSM with HC is currently EDI-OCT. In difficult differential diagnostic cases, it is recommended to use FA and MRI. Additionally, for identification of the cause of SRD in DSM, OCT-angiography and ICG-angiography can be used. Thus, diagnostics of DSM is difficult today primarily because of the low awareness of ophthalmologists about the presence of such macula pathology. Detection of this anatomical feature by means of ophthalmoscopy alone can be difficult and requires special skills and experience. The use of EDI-OCT, as well as FA and MRI in difficult differential diagnostic cases, and correct interpretation of the obtained data can help avoid diagnostic errors.

[Hyalocytes of the vitreous body and their role in ophthalmic pathology]

Hyalocytes of the vitreous body are variety of tissue macrophages that exercise various functions - from ensuring the synthesis of extracellular matrix components and modulating the immune response in the vitreous body to participating in different stages of inflammatory processes. Some aspects of the biology of hyalocytes remain poorly understood and controversial. However, the vitreous cells are starting to be considered a potential point of application in the treatment of diseases of the vitreous body and the retina.

[Effects of urokinase plasminogen activator on cultured human retinal epithelial cells]

AIM

to study the effects of urokinase plasminogen activator (UPA) on the human retinal pigment epithelium (hRPE) cell culture.

MATERIAL AND METHODS

The toxicity of 50 U/ml UPA was studied with the trypan blue exclusion test. Cell migration was assessed by the wound healing and modified Boyden chamber assays. Additionally, cell morphology, trypsin resistance, and Ki67 expression were investigated.

RESULTS

Trypan exclusion test did not reveal any cytotoxicity of 50 U/ml UPA against hRPE cells. The agent appeared able to induce cellular cluster formation and increase the number of spindle-shaped cells (6.4±2.4 cells/field and 67.3±3.2 cells/field in the controls and in the presence of 50 U/ml UPA, respectively, p<0.001). Cell migration in the Boyden chamber also showed a statistically significant increase (1.75-fold, p=0.012). Monolayer wounds were found to heal at an accelerated rate (p<0.05). This effect was dose-dependent, just like the increase in Ki67-positive cells (from 2.5 to 50 U/ml). Moreover, there was a reduction in trypsin resistance of the hRPE cells (the number of resistant cells in the control and 50 U/ml UPA cultures was 5.2±1.7 cells/field and 0.46±0.32 cells/field, respectively, p<0.001).

CONCLUSION

UPA, at concentrations of 50 U/ml or less, demonstrates no cytotoxicity against the hRPE cells. The effects of UPA on hRPE include stimulation of epithelial-mesenchymal transition, migration, proliferation, and intercellular interaction. At that, changes in migratory and proliferative activity are dose-dependent.

[Role of Chlamydia trachomatis intraocular infection in the development of proliferative vitreoretinopathy (experimental study)]

OBJECTIVE

To study the influence of C. trachomatis infection on proliferative vitreoretinopathy (PVR) stimulation and development in an experimental model.

MATERIAL AND METHODS

Intravitreal C. trachomatis injection was performed in 17 rabbits (right eyes) out of which 8 developed minimal chlamydial damage (1 was further subjected to histopathological examination with pathogen detection in ocular structures and other 7 were included in the study group). The control group consisted of 7 rabbits with no laboratory evidence of chlamydial infection. PVR was induced by 4 peripheral retinal punctures with a 19 G needle. Follow-up methods included ophthalmoscopy, ultrasonography, and PVR grading according to the Fastenberg classification. Histopathological examination, supplemented with pathogen detection by direct immunofluorescence in the study group, was performed at weeks 7 and 20.

RESULTS

PVR rate and severity were higher in the study group as compared with the controls (5 out of 7 rabbits, grade 2-4 vs. 2 out of 7 rabbits, grade 0-1, p<0.01). In the study group, histopathological examination performed before and after the induction of PVR revealed a pronounced lymphocyte and macrophage infiltration, characteristic of infectious inflammation. Similarly, extra- and intracellular chlamydial inclusions could be found in the retina and/or zones of proliferation throughout the whole study period. Inflammation signs (including those of proliferation) were reliably less significant in the controls.

CONCLUSION

C. trachomatis infection of the posterior segment contributes to PVR development due to associated chronic inflammation.

[Pathomorphology of vitreoretinal proliferative membranes: review]

Proliferative vitreoretinopathy (PVR) appears to be one of the main reasons of functional and sometimes also anatomical death of the eye after its damages and diseases as well as is one of the heavy complications of the post operation period at vitreoretinal surgery. PVR is characterized by the occurrence at first glial and then connective-tissue tensions on the fundus of the eye the basis of which is the formation of cellular-fibrillar pre- and subretinal membranes consisting of macrophagal, fibroplastic, glial and pigmentary-epithelial cells as well as of the substrates of extracellular matrix. The basis of the formation of proliferative membranes appears to be the same reparative processes which are observed at the cicatrisation of wound: cellular chemotaxis and mitosis, the synthesis of extracellular matrix, the processes of remodelling and contractions in newly formed cicatricial tissue. According to the data of histological investigations the proliferative membranes consist of: intercellular substances, presented by collagenous and elastinic fibers of different thickness; cellular components - fibroblasts, macrophages, glial cells, pigmentary-epithelial cells, and lymphocytes. The review showed that there are no significant differences in the structure of epi- and subretinal membranes in the patients with PVR develop against the background of principally different diseases which testifies to general genesis of development and formation of proliferative tissue in the cavity of eyeball. The complicated system of intercellular interrelations and interaction in the pathological focus, activates a whole complex of pathogenetic factors which conditions the development and formation of vitreoretinal proliferative membranes.

Mechanisms of recognition of the outlines of “vanishing” optotypes

The aim of the present work was to study the interaction between the optical properties of images of " disappearing" optotypes and their recognition thresholds. The "disappearing" optotypes were figures with complex outlines and had a unique property - they were close to the threshold of recognition and observation, which increases the accuracy of measurement of visual acuity and the subjects' attention to them. The recognition distances of "disappearing" optotypes were measured. A relationship was found between the recognition distance of "disappearing" optotypes and different optical density profiles on the one hand and the spatial and spatial frequency characteristics of the stimuli on the other. The decisive factor determining the threshold of recognition of optotypes in spatial frequency terms is its spatial frequency spectrum; that in spatial terms is the width of the black/white pair or black-white triad in the complex outline. Regardless of the shape of the optotype, one of the most important limiting factors was the concordance of this test with the scattering function of the subject's eye optics.

Objective measurement of human visual acuity by visual evoked potentials

Electrophysiological studies were performed to measure the threshold (upper end of range) spatial frequency using visual evoked potentials and comparison with visual acuity neuron 26 healthy subjects. The aim of the present work was to create a method for objective measurement of visual acuity. This was addressed by initial measurements using a universally accepted method of visual stimulation and processing of electroencephalograms, which allows errors due to individual differences in visual system function to be minimized. These experiments yielded a strong correlation between the threshold spatial frequency of the test grid yielding an evoked potential on presentation and visual acuity, in degrees, expressed as the resolving ability of the visual system for this optotype. A logarithmic relationship was found between these values and an equation allowing automated calculation of visual acuity (resolving ability) from electrophysiological data was derived. The results were independent of the subject's responses and therefore provides a maximally objective assessment of visual acuity.