[Area of the foveal avascular zone in patients with refractive errors]. / Ploshchad' foveal'noi avaskulyarnoi zony pri anomaliyakh refraktsii.

PURPOSE: To investigate the dependence of the area of the foveal avascular zone (FAZ) on axial eye length (AL) and to develop a feasible method for correcting this dependence. MATERIAL AND METHODS: The study involved 209 patients over the age of 18 years (209 eyes), of them 52 patients with AL of 20-22 mm (hyperopia group), 60 patients with AL of 25.5-28.5 mm (myopia group) and 97 patients with AL of 22.5-24.5 mm (emmetropia group). Optical coherence tomography angiography (OCTA) examination was performed on Cirrus HD-OCT 5000 with AngioPlex («Carl Zeiss Meditec¼, Germany). RESULTS: FAZ area was corrected using the Littmann-Bennett formula modified by A.A. Shpak and M.V. Korobkova. FAZ area values both in emmetropic patients and in patients with refractive errors varied over a very wide range. Before correction, AL had a significant influence on the FAZ area (mm2), which compared to the emmetropia group (0.27±0.09) was significantly reduced in the myopia group (0.21±0.07; p<0.000) and increased in the hyperopia group (0.31±0.11; p=0.015). The corrected FAZ area values did not differ in the compared groups. After correction the FAZ area decreased on average by 19% in the hyperopia group and increased by 25% in the myopia group. A chart and an Excel (Microsoft)/LibreOffice Calc program have been developed for correction of the FAZ area depending on the AL. CONCLUSION: Refractive errors, especially high-degree ones, have a significant effect on the FAZ area. This study proposes an original chart and a calculation program for correct interpretation of FAZ area measurements in patients with refractive errors, providing an accessible and quick way to assess the obtained results.

[Natural course of lamellar macular holes]. / Estestvennoe techenie lamellyarnykh makulyarnykh razryvov.

The issue of indications for surgical treatment of lamellar macular holes (LMH) remains debatable, especially considering the different opinions about the possibility of their progression. PURPOSE: To study natural course of LMH and to develop criteria of their progression. MATERIAL AND METHODS: The study analyses retrospective data of patients with LMH observed in S. Fyodorov Eye Microsurgery Federal State Institution from 2013 to 2018 who were examined by optical coherence tomography (OCT) at least 2 times with an interval between the initial and last examinations of at least 6 months. The examinations were carried out to evaluate the types of LMH and epiretinal membrane, the ellipsoid zone of photoreceptors and vitreoretinal interface, as well as calculate the changes in the quantitative parameters of the LMH. RESULTS: One hundred and three patients with LMH were identified; data of 65 patients (65 eyes) was studied in detail. The follow-up lasted 20.5±12.9 months on average. Statistically substantiated criteria for the progression of tractional and degenerative LMH were developed, taking into account the OCT changes most significant for each type of LMH. According to the proposed criteria, signs of marked progression were found in 2 (5.3%) of 38 patients with tractional and 4 (14.8%) of 27 patients with degenerative LMH. Moderate progression was detected in 2 (5.3%) patients with tractional and 2 (7.4%) patients with degenerative LMH. In two patients who were not included in the groups for calculating the criteria for progression, the formation of a full-thickness macular hole has occurred. CONCLUSION: One of the variants of the natural course of LMH can be its progression up to transition into a full-thickness macular hole. The proposed statistically substantiated criteria allows identifying dangerous progression of LMH, which should be taken into account when determining the treatment tactics.

[Effect of cataract extraction with intraocular lens implantation in patients with myopia on optical coherence tomography measurements]. / Vliianie intraokuliarnoi korrektsii na pokazateli opticheskoi kogerentnoi tomografii pri miopii.

INTRODUCTION: One important question for patients with both myopia and glaucoma is comparability of optical coherence tomography (OCT) data obtained before and after a significant change in eye refraction following cataract extraction surgery with implantation of intraocular lens (IOL). PURPOSE: To assess the impact of correcting moderate and high myopia during cataract phacoemulsification with IOL implantation (Phaco/IOL) on the parameters measured by OCT. MATERIAL AND METHODS: OCT was performed in 31 patients (31 eyes) with axial eye length of more than 25.5 mm before and the day after Phaco/IOL. Changes in 17 parameters of the retina, retinal ganglion cells-inner plexiform layer (GCIPL), peripapillary retinal nerve fiber layer (RNFL) and optic nerve head (ONH) were analyzed. RESULTS: Axial eye length was 26.94±1.09 mm in average (25.57-29.39 mm). The average refractive effect of the intervention was 8.44±4.16 D (3.75-19.0 Diopters). Signal strength in all OCT protocols was no lower than 5. Changes in the average values of OCT parameters after surgery were insignificant. They exceeded 1% of the pre-operation values only in 7 cases, including all 5 parameters of the ONH, and were significant only in 5 out of 17 parameters. For GCIPL and RNFL thickness, the changes on average did not exceed 0.9 µm, for retinal thickness in the macular area - 2.1 µm. In relative terms, the largest decrease (an average of -0.03 mm2; -2.5%) was in the optic disc area. CONCLUSION: In patients with high and moderate myopia, the parameters of the retina, RNFL, GCIPL, and ONH, as measured by OCT, changed insignificantly on the first day after Phaco/IOL (considering the signal strength of Cirrus HD-OCT device was not lower than 5).

[Axial ametropias of very high degree]. / Osevye ametropii vysokoi stepeni.

To characterize a complex of disorders developing in patients with extreme values of anteroposterior axis of the eye, it is necessary to create an appropriate nomenclature. As a topic for discussion, authors suggest to supplement the existing classifications of myopia and hyperopia with 'character of ametropia' section (axial, refractive, mixed) and the definition of ametropias of very high (ultra-high/extreme) degree (a criterion for myopia is: <-10 D). In prospect, classification of such ametropias should be based on the length of the anteroposterior axis of the eye.

[Effect of corneal refractive surgery on optical coherence tomography measurements]. / Vliianie keratorefraktsionnykh operatsii na pokazateli opticheskoi kogerentnoi tomografii.

The effect of significant changes in corneal power after refractive surgery on the parameters of optical coherence tomography (OCT) has not been sufficiently studied. PURPOSE: To study effects of corneal refractive surgery on optical coherence tomography (OCT) measurements in patients with moderate and high myopia. MATERIAL AND METHODS: OCT was performed in 62 patients (62 eyes) with myopia over 4 D before and one month after LASIK. The changes in 14 parameters of the thickness of the retina, ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL) were analyzed. RESULTS: The mean refractive effect was 7.07±2.02 D (4.0 to 11.75 D). Postoperative changes in the parameters analyzed were insignificant, averaging not more than 1.3% of the baseline value with the exception of pRNFL thickness in the temporal quadrant (2.2%). Only six of the 14 parameters were statistically significant - retinal thickness in the central subfield and the inner nasal quadrant, average and minimum thickness of GCIPL, and pRNFL thickness (mean and in the temporal quadrant). Individual changes of the parameters in most patients did not exceed the error of method. CONCLUSION: In patients with moderate to high myopia, LASIK operation has only a slight effect on the OCT parameters of the retina and pRNFL. Only in patients with very high myopia, the decrease over 10 D in corneal refractive power creates an optical effect of increasing the average thickness of pRNFL and GCIPL by 2-3 µm. This should be taken into account when examining such patients for glaucoma.

[Functional outcomes of idiopathic macular hole surgeries].

AIM: To study the dynamics of visual status and its correlation with morphological changes in patients operated for idiopathic macular hole (IMH). MATERIAL AND METHODS: The study enrolled 78 patients (82 eyes) whose ocular media remained transparent throughout the whole follow-up period that started 1 month after a successful IMH surgery and lasted for no less than a year. Two equivalent subgroups, 29 patients (30 eyes) each, were then formed and designated as «transparent media¼ (pseudophakic patients or those who remained free of cataract over the follow-up period) and «comparison¼. RESULTS: Only patients from the «transparent media¼ subgroup have consistently improved their visual functions by the end of the first year after surgery. Positive correlation has been found between an increase in best corrected visual acuity (BCVA) and a decrease in the size of the hyporeflective defect within the so called ellipsoid zone (correlation coefficient r=-0.50, p<0.01). The correlation was the strongest at months 3 and 12 (r=-0.57, p<0.01). It was also noticed that the lower BCVA at baseline the greater the treatment effect (ETDRS chart; r=-0.93, p<0.000). As a result, at the end of the follow-up period, BCVA varied little, reaching 0.5--1.0 in 76 cases and 0.3--0.4 in the remaining 6 cases. CONCLUSION: Modern IMH surgery ensures restoration of the outer retinal structure and high visual functions in most patients over a long term (more than a year of follow-up) on the only condition of transparent ocular media. Thus, the prediction of postoperative VA is of low significance in these patients.

[Combined assessment of early-stage primary open-angle glaucoma progression].

A total of 92 patients (92 eyes), including 52 patients with early-stage primary open-angle glaucoma and 40 glaucoma suspects, were enrolled in the study and followed up during 25.5 +/- 3.3 months on the average by means of computer perimetry, optical coherence tomography and Heidelberg retinal tomography. The prognoses for POAG progression made on the basis of these tests using both conventional (conservative) and extended (liberal) evaluation criteria demonstrated poor correspondence. It is suggested to consider glaucoma progression confirmed if characteristic changes are registered by at least two of the three methods.

[Evaluation of the macular ganglion cell layer by spectral-domain optical coherence tomography in diagnosis of early-stage glaucoma].

The new Cirrus HD-OCT software was used to measure the thickness of ganglion cell and inner plexiform layers (GCIPL) in macular region in 56 patients (56 eyes) with early-stage primary open-angle glaucoma (POAG) and 53 healthy controls (53 eyes). The diagnostic value of the best parameters of GCIPL for POAG detection was insignificantly lower as compared to the best parameters of the peripapillary retinal nerve fiber layer and optic nerve head.

[The effect of yellow filter intraocular lens on the macula after cataract phacoemulsification in patients with age macular degeneration].

Macula changes diagnosed with optical coherence tomography (OCT) within a year after cataract phacoemulsification (PE) with intraocular lens implantation with and without yellow filter are presented. 32 patients (36 eyes) with early stages of age macular degeneration (AMD) were included into the experimental group and 35 patients (36 eyes) served as controls. IOLs with yellow filter were implanted in 21 eyes, and in 15 cases IOLs without filter were used in each group. According to OCT data thickening of fovea and increasing of macula volume developed within 6 months after cataract PE. Implantation of yellow filter IOLs reduced the intensity of these changes after surgery in patients with AMD. The progression of early AMD into advanced stages within a year after PE was not observed.

[Optical coherence tomography in patients with foveal hypoplasia and high visual acuity].

Two clinical cases of children with foveal hypoplasia and high visual acuity examined using optical coherence tomography are presented. Genetic examination found oculocutaneous albinism type 1 in one patient. Potential causes and functional value of foveal hypoplasia are discussed.

[Evaluation of stereometric parameters of optic disc and nerve fiber layer using HRT III. Report 1: reproducibility and intraobserver variability coefficients].

29 patients with initial primary open angle glaucoma were examined using Heidelberg retinal tomograph III (HRT III). In one visit 2 observers took 2 measurements. Intra- and interobserver errors (reproducibility and intraobserver variability coefficient) were calculated for 13 stereometric parameters of optic disc and retinal nerve fiber layer (RNFL). Rim area, cup depth (mean, maximum) and linear cup/disc ratios showed to be minimally variable. Cup area and volume, disc/cup area ratio were found to have greater variability. When performed by different observers (each entering his own contour) reproducibility was 1,4 fold lower compared with intraobserver reproducibility.

[Evaluation of stereometric parameters of optic disc and nerve fiber layer using HRT III. Report 2: factors influencing reproducibility].

29 patients with initial primary open angle glaucoma were examined using Heidelberg retinal tomograph III (HRT III), factors influencing measurements reproducibility and variability were studied. The following factors were found to cause outliers in stereometric parameters of the optic nerve head and retinal nerve fiber layer: standard reference height showing large difference of measurements or very high values, significant difference of scan depth, small optic disc, astigmatism, old age, interobserver variability of disc area (contour line position). Considering these factors one can determine indications for control examination thus improving method accuracy.

[Evaluation of stereometric parameters of optic disc and nerve fiber layer using HRT II. Report 3: measurement error of spectral-domain optical coherence tomography compared with Heidelberg retinal tomograph III].

The aim was to study reproducibility and variability of measurements of retinal nerve fiber layer (RNFL) using spectral-domain optical coherence tomography (SOCT) and to compare with error of Heidelberg retinal tomograph (HRT). 29 patients with initial primary open-angle glaucoma were examined using Heidelberg retinal tomograph III (HRT III) and SOCT (Cirrus HD-OCT). Intra- and interobserver errors (reproducibility and intraobserver variability coefficient) for mean RNFL thickness and its thickness in temporal, upper, nasal and inferior quadrants. Mean RNFL thickness measured with SD-OCT showed the highest intra- and interobserver reproducibility and minimal variability. Intraobserver variability coefficient was 3 times lower as compared with the best parameter measured with HRT (rim area) and it was 7 fold lower as compared with mean RNFL thickness measured with HRT. Thus study of RNFL using SD-OCT showed high reproducibility and low variability particularly for mean RNFL thickness. The measurement error of SOCT is lower as compared with HRT and provides the most accurate study of RNFL.

[Errors of classical and spectral optical coherence tomography in the measurement of retinal nerve fiber layer in healthy individuals].

Two similar groups of healthy individuals were examined by optical coherence tomography (OCT) on a Stratus OCT 3000 (Carl Zeiss Meditec, Inc. USA) (n = 26) and by spectral OCT on a 3D OCT-1000 (Topcon, Japan) (n = 25). Each of two operators made two peripapillary retinal nerve fiber layer measurements during a session. The measurement error indicators (intraindividual standard deviation and repeatability rate) were determined for each of the operators and in the comparison of the latter. Spectral OCT ensured a reduction in the measurement error indicators as compared with classical OCT, which was significant when the measurement was made by a rather skilled operator.

[Brain-derived neurotrophic factor in diabetic retinopathy and asymptomatic edema of the optic nerve head].

Thirteen healthy individuals and 27 patients with diabetic retinopathy were examined (23 patients (23 eyes) with diabetic retinopathy being selected for analysis). The proposed indicator of optic nerve head (ONH) edema from the data of optical coherence tomography could more frequently diagnose asymptomatic ONH edema due to the detection of its early forms on 5 of the 23 eyes versus 3 eyes, as evidenced by biomicroophthalmoscopy (slit-lamp ophthalmoscopy). The patients were found to have a drastic reduction in the level of brain-derived neutrotrophic factor (BDNF) in plasma and lacrimal fluid. The most marked decrease in plasma BDNF was observed in patients with asymptomatic ONH edema. The tear content of BDNF was particularly low in patients with increased neuroretinal rim volume.

[Diagnostic capacities of optical coherent tomography in central serous chorioretinopathy].

Optic coherent tomography (OCT) was used to examine 123 patients with central serous chorioretinopathy (CSC) first detected in one eye; spectral OCT (SOCT) was also performed in 36 patients. According to SOCT data; CSC was characterized by preservation of the external borderline membrane and a drastic optic density reduction, and no coupling of the external and internal segments of photoreceptors; when the disease was prolonged, there were pronounced changes in external segments of photoreceptors--a notched contour, fragmentation, etc. OCT revealed pigment epithelium alterations (detachment or deformity) in 40.8% of cases whereas SOCT in all cases, including changes in small sizes, located at the periphery of the macular area. A coincidence of PE alterations was established from the data of SOCT and the points of fluorescein leakage on the angiograms. It is suggested that SOCT may be used to determine the localization of liquid filtration points in patients having contraindications to fluorescence angiography of the fundus of the eye.

[Role of optical coherent tomography in the detection of epiretinal membranes in unilateral idiopathic macular ruptures].

Two hundred and four patients (408 eyes) with unilateral idiopathic macular ruptures (IMR) were examined by optical coherent tomography (OCT), of them 39 patients also underwent spectral OCT (SOCT). The latter much more frequently revealed epiretinal membranes (ERMs): in the eye with IMR in 32 cases versus 10 cases; in the paired eye in 23 cases versus 6 cases by OCT. According to the SOCT data, ERMs had peripheral localization (further 3 mm from the center of the macular area) in 14 of the 32 eyes with IMR and in 13 of the 23 paired eyes; in 12 of the 23 patients, ERMs in the paired eye were detected in the absence of lamellar ruptures or any other foveal pathology. It is suggested that the tangential tractions developing in the presence of contracted ERMs are of possible importance as an additional and, in some cases, major factor in the pathogenesis of IMR.

[Comparative analysis of the results of microperimetry and conventional computed perimetry in health].

Twenty-one healthy volunteers aged 21 to 37 years (21 eyes) were examined on a MP-1 microperimeter and a Humphrey HFA II-750i perimeter by the 10-2 program. The standard stimulation parameters used on the microperimeter revealed a wide plateau in the central visual field due to the limited stimulus intensity range of MP-1. The comparable data on both perimeters could be obtained only with small-sized stimuli (Goldmann I). However, quantitative comparison demonstrated significant differences in the reduction of differential light thresholds from 2 degrees to 10 degrees from the fixation point. The studies have indicated that the technical characteristics of the MP-1 microperimeter does not allow one to elaborate algorithms for recounting the data to compare with those obtained on the Humphrey perimeter. It has been ascertained that the MP-1 microperimeter should not be used to solve the problems of conventional computed perimetry.

[Optical coherence tomography in the diagnosis of retinal alterations in the presence of pigmented choroidal tumors].

Optical coherence tomography (OCT) was used to examine 33 patients (33 eyes) with choroidal melanoma and 39 patients (39 eyes) with choroidal nevus. The magnitude of changes in the retina and its pigment epithelium above the pigmented choroidal neoplasms was found to be largely in proportion to their sizes. When primarily detected, choroidal melanomas had larger sizes and were significantly more frequently attended by neuroepithelial detachment, retinal edema, and evident impairments in the normal architectonics of the retina and its pigment epithelium above the tumor, neuroepithelial detachment in the foveal area, and these tumors tended to show a higher rate of pigment epithelial detachments above the tumor and foveal edema. However, in the presence of small neoplasm sizes (from 1 mm, but less than 2 mm), the patients with choroidal melanomas were observed to have more frequently neuroepithelial detachment and to tend to have a higher rate of retinal edema above the tumor.

[Role of optic coherent tomography in monitoring the efficiency of laser treatment for the exudative form of involutional macular degeneration].

Optic coherent tomography was used to monitor three cases of successful laser retinal coagulation in involutional macular degeneration followed by transsudative retinal detachment of the pigment epithelium and neuroepithelium to give rise to a subretinal neovascular membrane. The technique was shown to be of high informative value in providing an accurate localization of abnormal macular changes and in monitoring their state. The application of optic coherent tomography could reduce the number of control angiographies and, in a number of cases, to obviate a necessity of performing angiographic studies.