Chorioretinal Complex Research Articles

Ultrasonic registration of myopic changes in the eye of Japanese quail chicks raised under the different spectrum of everyday illumination

Abstract High-resolution ultrasound techniques are employed in ophthalmology for detecting age-related changes in the eyeball’s structure, diagnosing tumours and vascular conditions. Meanwhile, acoustic microscopy methods are widely used in laboratory animal research. Our experiments utilised a short ultrasonic pulse (30-80 MHz) and B/Z-scan mode with dynamic focusing. This study utilised these parameters to measure various ocular dimensions, including the longitudinal and transverse size of the eyeball, the thickness of the lens, and the scleral-cornea, vitreous and chorioretinal complex. The sample comprised individuals of varying ages, an adult bird (65 days), and chicks across four age stages (10, 23, 36, 45 days), all studied in situ. The method enabled observation of age-related alterations in ocular structures throughout the ontogenesis of the animal, illuminated daily using an incandescent lamp alongside yellow and blue light filters. The outcomes illustrate that the measurement technique’s sensitivity detects an anterior-posterior axis (APA) escalation of quail eyes with an error range of ±15 microns. The method’s sensitivity adequately analysed the impact of the spectral composition of everyday lighting on deviations in eye development.

Automatic segmentation of layers in chorio-retinal complex using Graph-based method for ultra-speed 1.7MHz wide field swept source FDML optical coherence tomography.

The posterior segment of the human eye complex contains two discrete microstructure and vasculature network systems, namely, the retina and choroid. We present a single segmentation framework technique for segmenting the entire layers present in the chorio-retinal complex of the human eye using optical coherence tomography (OCT) images. This automatic program is based on the graph theory method. This single program is capable of segmenting seven layers of the retina and choroid scleral interface. The graph theory was utilized to find the probability matrix and subsequent boundaries of different layers. The program was also implemented to segment angiographic maps of different chorio-retinal layers using "segmentation matrices." The method was tested and successfully validated on OCT images from six normal human eyes as well as eyes with non-exudative age-related macular degeneration (AMD). The thickness of microstructure and microvasculature for different layers located in the chorio-retinal segment of the eye was also generated and compared. A decent efficiency in terms of processing time, sensitivity, and accuracy was observed compared to the manual segmentation and other existing methods. The proposed method automatically segments whole OCT images of chorio-retinal complex with augmented probability maps generation in OCT volume dataset. We have also evaluated the segmentation results using quantitative metrics such as Dice coefficient and Hausdorff distance This method realizes a mean descent Dice similarity coefficient (DSC) value of 0.82 (range, 0.816-0.864) for RPE and CSI layer.

Optical coherence tomography angiography features of the chorioretinal complex and choriocapillaris perfusion before and after vitrectomy with conventional versus fovea-sparing internal limiting membrane peeling for idiopathic macular hole

Purpose: To assess optical coherence tomography angiography (OCTA)-measured changes in the chorioretinal complex and choriocapillaris perfusion density in the macula before and after vitrectomy with fovea-sparing versus conventional internal limiting membrane (ILM) peeling for idiopathic macular hole (IMH). Material and Methods: Eyes with stage-2 to stage-4 holes as per the classification by Gass received 25-G vitrectomy with conventional or fovea-sparing ILM peeling and gas tamponade with 20% SF6 or 15% С3F8. IMH diameter, foveal avascular zone (FAZ) area in the deep retinal plexus and choriocapillaris perfusion density (CPD) were assessed before and 1 month after surgery. Results: Totally, 70 patients had an IMH surgery in 71 eyes. The mean age ± standard deviation (SD) was 65.7 ± 6.8 years, median IMH duration (interquartile range or IQR), 3.0 (1.0-6.0) months, median best-corrected visual acuity or BCVA (IQR), 0.19 (0.1-0.25), and median maximum IMH diameter (IQR), 673.5 (549.5–1010.5) µm. In eyes with IMH and fellow eyes, the median FAZ area (IQR) was 0.51 (0.15–0.53) mm2, and 0.46 (0.10–0.74) mm2, respectively (р = 0.49), and mean CPD ± SD, 0.11 ± 0.06, and 0.29 ± 0.13 (р = 0.0001), respectively. Thirty-four eyes received conventional ILM peeling and 37 eyes, fovea-sparing ILM peeling, and there was no significant intergroup difference in baseline characteristics. One month after surgery, IMH closure was achieved in 63/71 eyes (i.e., the closure rate was 88.7% for total operated eyes, and 88.2% and 89.2%, respectively, for eyes in conventional ILM peeling and fovea-sparing ILM peeling groups), and median BCVA (IQR) improved to 0.60 (0.4–0.8) (р = 0.00001). After IMH closure, in operated eyes, median FAZ area (IQR) decreased to 0.30 (0.12–0.6) mm2, but the difference was not significant, whereas mean CPD ± SD increased significantly from 0.11 ± 0.06 to 0.25 ± 0.10 (р = 0.0001). No significant difference in OCTA-based retinal microcirculation and choriocappillaris characteristics was observed between the conventional ILM peeling and fovea-sparing ILM peeling groups. Conclusion: The presence of macular hole is accompanied by abnormal perfusion in the choriocapillaris, but the CPD recovers after IMH closure. Postoperative CPD recovery is not influenced by the type (conventional or fovea-sparing) of ILM peeling.

Determination of modes for safe application of selective micro-pulse individual retinal therapy of the macular zone using the modeling based on the theory of activated complex

Purpose: to make modeling of various modes of laser radiation, to assess the degree of damage to the retinal pigment epithelium and adjacent structures, and to determine modes and safety conditions of selective micro-pulse individual retinal therapy based on the theory of activated complex. Materials and methods. The authors have modeled the degree of damage to the chorioretinal complex and adjacent structures using the activated complex theory with the Eyring equation. The following definitions were used to determine the regime quality and safety conditions: micro-pulse mode is a mode with fixed values of micro-pulse duration, duty cycle and the number of pulses in the packet; power is a variable parameter. Efficiency is the ratio of the amount of denatured protein inside the retinal pigment epithelium layer to the total amount of protein in it. Selectivity is the ratio of the amount of denatured protein inside the retinal pigment epithelium layer to the total amount of denatured protein. Relative harmfulness is the ratio of denatured protein volume outside the retinal pigment epithelium to the volume of protein in it. Results and discussion. The quality of micro-pulse mode was found as depending on the selectivity value with efficiency equal to 90 %. With the efficiency value less than 50 %, the mode is non-selective, with more than 67 % – selective. Safety conditions for selective micro-pulse modes have been established, taking into account safety of the neurosensory retina and choroid in terms of relative harmfulness which should not exceed 1. Parameters at which micro-pulse modes have high values (more than 90 – 99) of efficiency and selectivity at the same time have been determined as well. It requires single pulse mode, micro pulse duration of 25 microseconds and power from 6 to 8 W. To expand the combination of parameters, it is necessary to be able to freely change them in increments of 1 pulse, 5 microseconds, 100 mW, with long interval and short duty cycle. These technical capabilities can be realized and implemented into clinical practice by manufacturers of laser devices. Conclusion. For selective micro-pulse individual retinal therapy of the macular zone with existing lasers, the following recommendation are to be observed: micro-pulse modes with pulse duration no more than 200 microseconds, short duty cycle less than 5 % and number of pulses in an envelope no more than 5; relative harmfulness less than one, radiation power selection, personalized patient’s characteristics.

Morphometric study of the chorioretinal complex of laboratory animals in an experiment with electrocoagulation of the retina via transvitreal access

Retinal detachment occurs primarily as a result of diabetes, high myopia, and eye injuries. Restoration of the anatomical integrity of the detached retina is performed urgently using methods that allow fixing the displaced layers of the retina in their usual place – cryo-, laser-, and electropexy methods. There is no consensus on which of these methods is better. Our study is devoted to electropexy, namely high-frequency electrocoagulation, and describes an experiment on modeling the restoration of the anatomical integrity of a detached retina on lab rabbits of the chinchilla breed using an instrument of original design – a monopolar coagulator with a 25 G tip. 33 rabbits (66 eyes) were divided into four groups: the control group (6 animals) and 3 groups (9 animals each), which were operated using an electric current with a frequency of 66 kHz, a current of 0.1 A, and voltages of 10–12 V (I group), 12–14 V (II group) and 14–16 V (III group) and transvitreal access. All rabbits were subjected to euthanasia: rabbits of the control group (intact) – at the beginning of the experiment, operated rabbits (I–III groups) – 30 days after the operation. Eyes were enucleated, tissues of chorioretinal structures were stained with hematoxylin-eosin and studied under light microscopy with measurement of retinal thickness using the software "ImageFocusAlpha" (Netherlands) version 1.3.7. The results of morphological and morphometric studies were compared with the results of our other experiment conducted earlier with similar conditions of impact on chorioretinal structures, but with suprachoroidal access. The research and comparison showed that both with suprachoroidal and transvitreal accesses, with a current frequency of 66 kHz and a current strength of 0.1 A, the optimal exposure voltage is 10–12 V, and the best approach is the suprachoroidal access. Keywords: vitreoretinal surgery, retinal detachment, retinal thickness.

Physical modelling to assess the effect of micropulse modes of laser radiation at the chorioretinal complex of the human eye based on the theory of activated complex

Purpose: to construct a physical model based on the theory of activated complex (TAC) with indicators ΔH and ΔS mentioned in works of G.I. Zheltov and his colleagues so as to assess the impact of laser radiation micropulse modes at the chorioretinal complex (CRC), as well as to compare it with models based on the Arrhenius integral and with results of micropulse mode testing using autofluorescence method.Material and methods. Modeling of the degree of damage to CRC and adjacent structures was carried out using Eyring equation. Values of ΔH = 360 000 J/mol and ΔS = 890 J/mol·deg for complex of proteins and other RPE organic structures were determined by G.I. Zheltov and co-authors in vivo in a series of laser experiments on primates. For modeling, absorption coefficient of 460 cm–1 was used, for wavelength 577 nm – 10-micron-thick RPE layer and transmission 37 %. Micropulse mode testing (50 μs, 2.4 %, 10 ms, 100 mkm, 0.4–1.9 W) was performed using Navilas 577s navigation laser in patients aged 35–46 with appearance of types 2–3 by the Fitzpatrick scale; results of this testing were assessed using short-wave autofluorescence (488 nm) method.Results. A physical model based on TAC and Eyring integral was constructed. Results of modeling of the degree of RPE injury depending on power coincide with the results of testing of micropulse mode in patients according to autofluorescence method. The average RPE absorption coefficient equal to 440 cm–1 for patients aged 35–46 years and with appearance of type 2–3 by the Fitzpatrick scale was clarified.Conclusion. The computer modeling based on TAC using the Eyring equation with ΔH and ΔS for a complex of proteins and other RPE organic structures, which are described in works of G.I. Zheltov and his co-authors, has shown a high degree of compliance with the results of micro-pulse mode testing in real patients. Modeling does not require adjustment of any free parameters unlike approaches based on the Arrhenius equation; it also allows to find absorption coefficients for a small sample of patients and to assess the level of laser radiation damage to RPE and adjacent structures.

The impact of scheduled hemodialysis on clinical-functional and morphometric ophthalmological status of patients with a terminal kidney disease

The literature review discusses the impact of scheduled hemodialysis on the state of the anterior part of the eye, the chorioretinal complex, the central and peripheral vision. The hemodialysis procedure is accompanied by a decrease in basal tear production, quickening of the tear film break-up, and an abnormal ocular surface disease index. Thinning of the corneal center is not accompanied by significant keratometric changes. Intradialytic thinning of the choroid and reduction of ocular perfusion pressure may be involved in the progression of ischemic eye diseases. Lower visual acuity is associated with the instability of the lens and choroid thickness. The impact of hemodialysis on the peripheral vision has not been sufficiently investigated. The correlations of ophthalmic changes with systemic effects of the dialysis are ambiguous. The inconsistency of the research results requires that the research should be continued.

State of microcirculation in the retina and choroid according to optical coherence tomography with angiography data in children with posterior and panuveitis

AIM: Retinal and choroidal microvascular changes analysis in children with posterior and panuveitis using optical coherence tomography with angiography (OCTA) and determination of the possibility of using this method in activity assessment and disease monitoring.
 MATERIAL AND METHODS: 24 children with uveitis were examined. The age of children was from 8 to 18 years old (38 affected eyes). All included patients were divided into two groups: with posterior uveitis (27 eyes) and with panuveitis (11 eyes). In each of the groups, subgroups with active and inactive uveitis were identified. In addition to the standard examination OCTA was performed. Foveal avascular zone (FAZ) area, perfusion density in the superficial and deep vascular plexuses of the retina (SVRP, DVRP) and also in the layers of choriocapillaries and large and medium vessels of the choroid were studied. The control group consisted of 10 paired healthy eyes.
 RESULTS: Аll eyes with posterior and panuveitis were characterized by the irreversible decrease in perfusion density in DVRP. In eyes with active chorioretinitis was also detected the reversible decrease in perfusion density in SVRP, layers of choriocapillaries and large and medium vessels of the choroid. The formation of choroidal neovascular membranes (CNM) in patients with panuveitis with choroiditis was accompanied by the decrease in perfusion density at all levels studied. In eyes with chorioretinitis and CNM the decrease in perfusion density was detected in DVRP and the area of FAZ increased.
 CONCLUSION: The features of microcirculation in the chorioretinal complex identified using OCTA in children with posterior and panuveitis can improve the diagnosis and monitoring of these diseases.

Spatio-temporal optical coherence tomography provides full thickness imaging of the chorioretinal complex.

Despite the rapid development of optical imaging methods, high-resolution invivo imaging with penetration into deeper tissue layers is still a major challenge. Optical coherence tomography (OCT) has been used successfully for non-invasive human retinal volumetric imaging invivo, advancing the detection, diagnosis, and monitoring of various retinal diseases. However, there are important limitations of volumetric OCT imaging, especially coherent noise and the limited axial range over which high resolution images can be acquired. The limited range prevents simultaneous measurement of the retina and choroid with adequate lateral resolution. In this article, we address these limitations with a technique that we term spatio-temporal optical coherence tomography (STOC-T), which uses light with controlled spatial and temporal coherence and advanced signal processing methods. STOC-T enabled the acquisition of high-contrast and high-resolution coronal projection images of the retina and choroid at arbitrary depths.

Сканирующая лазерная офтальмоскопия в диагностике ламеллярного макулярного разрыва с эпиретинальной пролиферацией

Optical coherence tomography (OCT) technology has determined the possibility of in vivo study of morphostructural and morphometric changes in the central zone of the retina, including epiretinal proliferation. Scanning laser ophthalmoscopy (SLO) allows assessing changes in the vitreoretinal interface and chorioretinal complex "at different depths", the use of this method for lamellar macular holes (LMR) can be used not only for diagnosis, but also for assessing changes and the extent of the process. Purpose. To determine the possibilities of SLO in diagnosing and assessing the prevalence of epiretinal proliferation in lamellar macular holes in comparison with OCT data. Material and methods. In a study conducted on the basis of S. Fyodorov Eye Microsurgery Federal State Institution, Saint Petersburg branch, 48 patients with an established diagnosis of LMR were included, while epiretinal proliferation was diagnosed in 27 (52.6%) patients by OCT. SLO was performed in 21 patients with epiretinal proliferation diagnosed by OCT. Results. The best visualization of epiretinal proliferation was achieved by processing the image with a decrease in the intensity of red and an increase in blue and green. With epiretinal proliferation, there was a lower maximum correctable visual acuity and pronounced structural changes in the retina: a foveolar tubercle in 6 (12.5%) patients, a violation of the ellipsoidal zone in 10 (20.8%) of 48 patients, while its length was 110.26±19.85 µm. An inverse correlation was established between the values of the epiretinal proliferation area and the index of the minimum retinal thickness (R=-0.7, P=0.005), which indirectly confirms the gradual loss of retinal tissue during LMR due to the development of epiretinal proliferation. Conclusion. The performance of SLO allows visualization of epiretinal proliferation and determination of its area, which can be useful both in the dynamic observation of LMR and in planning surgical treatment for this pathology.

Morphological changes in eyes after suprachoroidal high-frequency electrosurgical treatment of the retina

A variety of methods and approaches are used for the surgical treatment of retinal detachment, among which high-frequency electrocoagulation through the suprachoroidal access has attracted the attention of researchers. The research question concerned the selection of the optimal mode of electrocoagulation with the help of a monopolar instrument of the original design, during which a strong chorioretinal adhesion occurs in a short period of time after surgical intervention, there is no need for tamponade, and the destruction of cells of chorioretinal structures is minimized, which is associated with the temperature factor of electrocoagulation. The study was conducted on 52 rabbits (104 eyes), which were divided into 4 groups: Group I – exposure voltage 10–12 V, frequency 66 kHz, current strength 0.1 A (16 animals, 32 eyes); Group II – exposure voltage 12–14 V, other parameters are identical (16 animals, 32 eyes); Group III – exposure voltage 14–16 V, other parameters are identical (16 animals, 32 eyes); Group IV– 4 intact rabbits, 8 eyes (control). The animals were euthanized, the eyes were enucleated. Fragments with areas after electrocoagulation were fixed on a device of the original design, which measured the strength of the chorioretinal adhesion on an electronic jewelry scale by pulling a thread tied to the sample until the sample ruptured. The tissues of the chorioretinal complex were also studied by light microscopy after staining histological sections with hematoxylin-eosin. According to indicators of chorioretinal junction strength, the optimal exposure voltage was 10–12 V. Destruction of cells of the chorioretinal complex at this voltage did not differ from destruction using voltages of 12–14 V and 14–16 V, but the strength of chorioretinal junction was the greatest after 1 hour. 1 week and 2 weeks after surgery. Keywords: high-frequency electrocoagulation, chorioretinal surgery, retinal detachment, strength of chorioretinal adhesion.

Mixed (combined) phenotype of the late stage of age-related macular degeneration

With multimodal visualization of the chorioretinal complex structures using modern research methods, it was possible to isolatea mixed, or combined, phenotype of the late stage of age-related macular degeneration (AMD). Early detection of this AMD form is of vital importance not only for accurate diagnosis, but for choosing optimal management tactics for patients. The paper presents two clinical cases with different variants of the development of the mixed phenotype of the late AMD stage. In one case, the long-lasting “geographic atrophy” (GA) was complicated by the development of choroidal neovascularization, while in the other case GA appeared during the treatment of wetAMD.

Ультраструктурні зміни елементів хоріоретинального комплексу щурів після моделювання деприваційної осьової міопії, діабетичної ретінопатії та при їх поєднанні

Ультраструктурні зміни елементів хоріоретинального комплексу щурів після моделювання деприваційної осьової міопії, діабетичної ретінопатії та при їх поєднанні

Ультраструктурні зміни клітин хоріоретинального комплексу очей щурів у віддалені строки після ін’єкції суміші 40% етанолу і 100% метанолу

Ультраструктурні зміни клітин хоріоретинального комплексу очей щурів у віддалені строки після ін’єкції суміші 40% етанолу і 100% метанолу

Возможность оптоакустического мониторинга для термометрического контроля субпорогового лазерного воздействия на структуры хориоретинального комплекса

Возможность оптоакустического мониторинга для термометрического контроля субпорогового лазерного воздействия на структуры хориоретинального комплекса

Biomechanical properties of optic nerve and retrobulbar structures with 2D and 3D shear wave elastography in patients affected by glaucoma

This study consists of an elastosonography evaluation of both eyes of 40 glaucomatous patients and 40 healthy subjects.We used shear wave elastography with a one-dimensional-array probe to capture two-dimensional images in order to study the optic nerve near the papilla, chorioretinal complex, lateral rectus muscle, and periorbital fat tissue. Furthermore, we used a two-dimensional array probe to capture three-dimensional images to study the optic nerve in toto with multilevel sampling. We obtained qualitative and quantitative data (“absolute” stiffness values). Then, we have investigated these tissue also measuring the “stiffness ratio” values.Statistically significant differences (p < 0.05), between glaucomatous patients and healthy patients, were noted in “absolute” stiffness values in the two-dimensional analysis at the emergence of the optic nerve and chorioretinal complex, and in the three-dimensional analysis at the emergence of the optic nerve (level I°). This result was supported by the statistically significant differences in the “stiffness ratio” values between the optic nerve and the adjacent adipose tissue, obtained both in two- and three-dimensional analyses.Data were subsequently compared with diagnostic tests currently used for glaucoma, which showed a sensitivity of 83% and specificity of 80% relative to those of elastosonography.We propose the use of elastosonography to verify the existence of pathological changes in the mechanical and elastic properties of peri-ocular structures and their variations as a complementary tool in the diagnosis of glaucoma and for follow-up during treatment.

Ocular vascular changes during pregnancy: an optical coherence tomography angiography study.

Pregnancy is a period presenting with many physiological adaptation mechanisms. One of the structures in which these mechanisms are observed is ocular tissues. The cornea, lacrimal and meibomian glands, and chorioretinal complex are all among the structures affected by changes during pregnancy. In this study we aimed to evaluate the macular and optic disc vessel density(VD) changes by Optical Coherence Tomography Angiography (OCTA) imaging in pregnancy. A total of 248 eyes from 124 pregnant women and 80 eyes from 40 healthy control women were involved. Vessel densities of macula were evaluated for superficial capillary plexus (SCP) and deep capillary plexus (DCP) in whole macula, foveal, parafoveal and perifoveal region. Peripapillary and whole optic disc VDs were also evaluated. Vessel densities of macula and optic disc were compared between control individuals and pregnant women. Vessel densities in different trimesters were also evaluated. Modest but significant differences in VDs of whole macula of SCP and DCP were observed in pregnancy group. Additionally, perifoveal and parafoveal region of SCP, whole disc and radial peripapillary capillary VD were significantly higher in pregnancy group. There was no correlation between VD ratios of macula and optic disc and pregnancy weeks and trimesters. This is the first study focusing on the OCTA parameters in pregnant individuals. These findings suggest that physiological changes during pregnancy are not limited to the cornea, eyelids and the choroid but also to the retinal and optic disc vasculature.

Структура хориоретинальногокомплекса глаз кролика после витрэктомии. Сообщение 3. Ирригация витреальной полости раствором температурой 36°С

Структура хориоретинальногокомплекса глаз кролика после витрэктомии. Сообщение 3. Ирригация витреальной полости раствором температурой 36°С

Экспериментальное обоснование оптоакустического контроля субпорогового лазерного воздействия на структуры хориоретинального комплекса

Экспериментальное обоснование оптоакустического контроля субпорогового лазерного воздействия на структуры хориоретинального комплекса

The Personalized Approach to the Chronic Central Serous Chorioretinopathy Treatment Based on the Navigated Micropulse Laser Technology

The Purpose— to develop the technology and to evaluate the clinical results of personalized laser treatment of patients with chronic central serous chorioretinopathy (CSC) in a micropulse mode with individual selection of energy parameters on the navigation system Navilas 577s.Patients and Methods. 19 patients (22 eyes) with CSC after micropulse laser treatment were analyzed. The initial best corrected visual acuity (BCVA) was 0.4 to 1.0. According to OCT, the height of the detachment of the neurosensory retina varied from 83 to 259 microns. Retinal sensitivity of the central zone was from 20.2 to 29.7 dB. Before laser treatment were individually selected the optimal energy parameters for each patient. The treatment was performed on a Navilas 577s laser system. The follow-up were 1 and 3 months.Results. 1 month after treatment the positive dynamics of functional and anatomical results in all patients was observed. Mean BCVA increased in the group to 0.81 ± 0.04. The central retinal sensitivity raised on average in the group up to 25.7 ± 0.6 dB. After 3 months, mean BCVA was 0.96 ± 0.02. Mean central retinal sensitivity increased to 26.4 ± 0.57 dB. The study revealed a high correlation between visual acuity and the central retinal thickness (0.72) and medium correlation between foveal retinal sensitivity and central retinal thickness in fovea (0.60), respectively. The correlation among visual acuity, retinal sensitivity and the symptom’s duration of the disease is negative medium (-0.63) and significant (-0.72), respectively.Conclusions. The developed personalized technology of laser treatment of chronic central serous chorioretinopathy with a micropulse mode with an individual selection of energy parameters on the Navilas 577s navigation system showed high clinical efficiency and safety. It has been established that in the course of the longstanding duration of the disease irreversible changes in the chorioretinal complex structure occured, thinning of the foveal photoreceptors layer leading to a decrease in the central retinal sensitivity and visual acuity, which substantiate the necessity for early and maximally functional-saving treatment.