Inner Segments Of Photoreceptors Research Articles

Reduced contrast sensitivity function is correlated with changes to cone photoreceptors in simple high myopia.

To investigate the contrast sensitivity function (CSF) changes in simple high myopia (SHM) and evaluate the correlations between these changes with the early changes in the retinal microstructure. This prospective study comprised 81 subjects, 20 with emmetropia (EM), 26 with low myopia and moderate myopia (LM/MM), and 35 with SHM. The area under the log CSF curve (AULCSF) and the cut-off spatial frequency (Cut-off SF) were employed as measures of CSF. Adaptive optics (AO) was employed to quantify the cone density, spacing, and regularity. The thickness and blood flow of the retinal sublayers were determined from vertical and horizontal optical coherence tomography angiography (OCTA) A-scans. Swept-source optical coherence tomography (SS-OCT) was employed to analyze the choroidal thickness (CT) and choroidal vascularity using a custom algorithm. Differences in the retinal and choroidal parameters, cone distribution, AULCSF, and Cut-off SF were compared among the three groups. Multivariate linear mixed models were used to elucidate the associations between photoreceptor morphological alterations, retinal and choroidal parameters, and AULCSF. The AULCSF and Cut-off SF were significantly lower in the SHM group compared to the EM and LM groups (p < 0.05). The SHM group had less cone density, larger cone spacing, and lower cone regularity than the EM and LM/MM groups (p < 0.05). Moreover, the thickness of the inner segment of photoreceptors (IS), retinal pigment epithelium (RPE) layer and choroid were reduced, and the outer segment of photoreceptors (OS) was thicker in the SHM group compared to the EM and LM/MM groups (all p < 0.05). A longer axial length (AL) was correlated with decreased AULCSF, cone density, and cone spacing (r = -0.800 to 0.752, all p < 0.050). Additionally, decreased CSF was correlated with lower cone density (r = 0.338, p = 0.035). Decreased contrast sensitivity was observed in patients with SHM and cone density was significantly correlated with reduced AUCSF.

Role of monocarboxylate transporters in AMPK-mediated protection against excitotoxic injury in the rat retina

Activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway protects against N-methyl-D-aspartic acid (NMDA)-induced excitotoxic retinal injury. AMPK activation enhances fatty acid metabolism and ketone body synthesis. Ketone bodies are transported into neurons by monocarboxylate transporters (MCTs) and exert neuroprotective effects. In this study, we examined the distribution and expression levels of MCT1 and MCT2 in the retina and analyzed the effects of pharmacological inhibition of MCTs on the protective effects of metformin and 5-aminoimidazole-4-carboxamide (AICAR), activators of AMPK, against NMDA-induced retinal injury in rats. MCT1 was expressed in the blood vessels, processes of astrocytes and Müller cells, and inner segments of photoreceptors in the rat retina, whereas MCT2 was expressed in neuronal cells in the ganglion cell layer (GCL) and in astrocyte processes. The expression levels of MCT2, but not MCT1, decreased one day after intravitreal injection of NMDA (200 nmol). Intravitreal injection of NMDA decreased the number of cells in the GCL compared to the vehicle seven days after injection. Simultaneous injection of metformin (20 nmol) or AICAR (50 nmol) with NMDA attenuated NMDA-induced cell loss in the GCL, and these protective effects were attenuated by AR-C155858 (1 pmol), an inhibitor of MCTs. AR-C155858 alone had no significant effect on the retinal structure. These results suggest that AMPK-activating compounds protect against NMDA-induced excitotoxic retinal injury via mechanisms involving MCTs in rats. NMDA-induced neurotoxicity may be associated with retinal neurodegenerative changes in glaucoma and diabetic retinopathy. Therefore, AMPK-activating compounds may be effective in managing these retinal diseases.

CHANGES IN THE STRUCTURAL ORGANIZATION OF CELLULAR COMPONENTS IN THE RETINAL LAYERS AND LINKS OF ITS HEMOMICOCIRCULATORY BED DURING THE CHRONIC PERIOD OF EXPERIMENTAL OPIOID EXPOSURE AND THE CORRECTION OF THESE CHANGES AT THE ULTRASTRUCTURAL LEVEL

Over the past twenty years, the experimental direction of research has been the most relevant in morphology to study the dynamics of the course of nosologies. In terms of the dynamics of the occurrence of pathomorphological manifestations at the cellular, tissue, organ, and organism levels, it off ers a larger variety of pathology investigations. The study of the retina in the norm and the processes of modifying its structural reorganisation under the eff ect of various nosologies are accorded high importance in the scientifi c literature written by both domestic and international professionals. Despite these eff orts, the problem of opioid retinopathy on prolonged experimental opioid exposure remains essential. It is still unknown, in particular, if the correction of the chronic period of experimental opioid exposure may stabilise pathomorphological symptoms in the retinal layers and linkages of its hemomycrocirculatory bed. The purpose of the research is to fi nd out the features of structural reorganization in the retinal layers and links of its hemomicrocirculatory bed in the chronic period of experimental opioid exposure and the correction of these changes with pentoxifylline.Material and methods. The research used 34 male, sexually mature, non-breeding rats that ranged in weight from 160 to 270 g and were 4.5 to 7.5 months old as its subject matter. The correction dose of pentoxifylline was 2.857 mg/kg. At the end of the 10th week, the material was taken for ultrastructural examination of the retina. Before the sampling of the experimental site material, the animal was withdrawn from the experiment using diethyl ether. The eyeballs of rats were used as a material for ultrastructural examination. Ultrastructural preparations were prepared according to the generally accepted method. As a result of our research of the retina at the end of the tenth week in rats, which were injected with an opioid for six weeks, and subsequently discontinued for four weeks, the phenomena of degeneration of the pigment epithelium, destruction of the membrane discs of the outer segments of the photoreceptors, degenerative changes in the inner segments of the photoreceptors, degenerative and necrotic changes of individual photoreceptors developed. Degeneration and necrosis processes were detected in bipolar and amacrine neurons. Rats were injected with the opioid for six weeks, with its cancellation and subsequent four-week correction with pentoxifylline. After ten weeks of the experiment, degenerative changes in the apical microvilli of the pigment epithelium, destruction of the membrane discs of the outer segments of the photoreceptors, degeneration of bipolar and amacrine neurons, moderately pronounced discirculatory changes, and reactive processes of glial elements were detected. In rats given an opioid for six weeks, followed by four weeks of an opioid with pentoxifylline administration, fl ushing, stasis, and perivascular oedema in the choroidal arteries were established ten weeks later. Degeneration and necrosis of the pigment epithelium, degeneration and destruction of the membrane discs of the outer segments of photoreceptors with separation of individual outer segments, degeneration of the inner segments of photoreceptors, degeneration and necrotic changes of photoreceptors, degeneration and necrotic changes of bipolar and amacryne neurons, Muller cells, degeneration of ganglion neurons, hyperemia, stasis and perivasal oedema in the vessels of the ganglion layer, the layer of nerve fi bers, in the inner mesh layer.

Dynamics of morphological changes in the cellular layers of retina in the long-term experimental opioid exposure

Relevance of research. There is enough information in the foreign and domestic specialized literature on the issue of morphological reorganization of cells and tissues during experimental opioid exposure and other types of toxic effects on the body today. At present, the issue of structural reorganization in the layers of the retina and disruption of its blood supply processes during subchronic and chronic periods of experimental opioid exposure remains unclear. That is why we decided to supplement, expand and deepen information about these processes by conducting our own research in this direction. The purpose of the study is to clarify the dynamics of pathomorphological changes in the layers of the retina and the links of its hemomicrocirculatory channel in the long term of experimental opioid exposure.Material and methods. The research material was sexually mature, outbred, white male rats, 56 animals in number, weighing 160-270 g, aged 4.5-7.5 months. The initial dose of nalbuphine during the first 2 weeks was 0.212 mg/kg, the next 2 weeks (III-IV weeks) – 0.225 mg/kg, the next (V-VI weeks) – 0.252 mg/kg, the next (VI-VIII weeks ) – 0.260 mg/kg, the next (VIII – X weeks) – 0.283 mg/kg, the next (X – XII weeks) – 0.3 mg/kg, and during (XII – XIV weeks) – 0.45 mg/ kg. Before taking the material of the experimental site, the animal was removed from the experiment with the help of diethyl ether. Rat eyeballs were used as a material for ultrastructural research, considering the preservation of the topographic ratio of the eye membranes. Ultrastructural preparations were prepared according to the generally accepted method. Research results. At the end of the eighth week and the tenth week, persistent hyperemia of the choroidal vessels, degenerative and necrotic changes in the cells of the pigment layer, degeneration of the outer segments of photoreceptors, shortening and fragmentation of mitochondrial cristae of the inner segments of photoreceptors, necrotic changes in the nuclei of individual photoreceptors, degeneration of axons of the outer and inner reticular layers, as well as degenerative and necrotic changes of bipolar and amacrine cells, hypertrophy of processes of Müller cells, degeneration of ganglion cells, hyperemia and perivascular edema of vessels of the outer and inner reticular layers were revealed. After twelve and fourteen weeks, the initial stages of development with subsequent progression of sclerotic changes of Bruchʹs membrane were first detected. The phenomena of degenerative and necrotic changes in the cells of the pigment layer, destruction of the membrane of the outer segments of photoreceptors, degenerative changes in the axons of the outer and inner reticular layers and the layer of nerve fibers, degenerative and necrotic changes in bipolar and amacrine cells, hypertrophic changes in processes of Muller cells, hyperemia and stasis gradually increased, perivascular swellings in the vessels of the inner reticular layer, ganglionic layer and layer of nerve fibers, reactive changes in Muller cells and protoplasmic astrocytes. Conclusion. In the long-term course of experimental opioid exposure, irreversible pathomorphological changes occurred and subsequently progressed, which were caused by an increase in dyscirculatory manifestations in the superficial and deep vascular networks of the retina, causing the deepening of edema phenomena with further compression and hypoxia in the thickness of the retinal layers.

Evaluation of Photobiomodulation and Boldine as Alternative Treatment Options in Two Diabetic Retinopathy Models.

Diabetic retinopathy causes progressive and irreversible damage to the retina through activation of inflammatory processes, overproduction of oxidative species, and glial reactivity, leading to changes in neuronal function and finally ischemia, edema, and hemorrhages. Current treatments are invasive and mostly applied at advanced stages, stressing the need for alternatives. To this end, we tested two unconventional and potentially complementary non-invasive treatment options: Photobiomodulation, the stimulation with near-infrared light, has shown promising results in ameliorating retinal pathologies and insults in several studies but remains controversial. Boldine, on the other hand, is a potent natural antioxidant and potentially useful to prevent free radical-induced oxidative stress. To establish a baseline, we first evaluated the effects of diabetic conditions on the retina with immunofluorescence, histological, and ultrastructural analysis in two diabetes model systems, obese LepRdb/db mice and organotypic retinal explants, and then tested the potential benefits of photobiomodulation and boldine treatment in vitro on retinal explants subjected to high glucose concentrations, mimicking diabetic conditions. Our results suggest that the principal subcellular structures affected by these conditions were mitochondria in the inner segment of photoreceptors, which displayed morphological changes in both model systems. In retinal explants, lactate metabolism, assayed as an indicator of mitochondrial function, was altered, and decreased photoreceptor viability was observed, presumably as a consequence of increased oxidative-nitrosative stress. The latter was reduced by boldine treatment in vitro, while photobiomodulation improved mitochondrial metabolism but was insufficient to prevent retinal structural damage caused by high glucose. These results warrant further research into alternative and complementary treatment options for diabetic retinopathy.

ULTRASTRUCTURAL ORGANIZATION OF THE RETINA LAYERS OF THE RAT IN NORM

The use of experimental animals with the aim of studying the dynamics of morphological changes requires deep knowledge of the initial indicators of the structure of the studied object in norm. In scientifi c medical literature, great importance belonges to the study of the retina in norm and the processes of changes in its structure under the infl uence of various nosologies. Considering the complexity of the retina structure and its role in the receiving information from the surrounding environment, it is important to understand the peculiarities of its layered organization in order to create a morphological basis for further comparing the experimental material and comparing it with the initial indicators of the norm with the results obtained at diff erent periods of the experimentally reproduced pathology. The aim of the study was to fi nd out the peculiarities of the layered structure of the cellular elements of the retina on the ultrastructural level in norm. Material and methods. The research material was 10 sexually mature, purebred male rats, weighing 160 g, aged 4.5 months. Before taking the material of the experimental area, the animal was removed from the experiment with the help of diethyl ether. Rat eyeballs were used as material for ultrastructural research. Ultrastructural samples were prepared according to the generally accepted method. As a result of our study of the retina of an intact group of animals, its layers preserved a clear stratifi cation architecture. The layer of the pigment epithelium was localized on Bruch’s membrane, choroidal vessels contained single erythrocytes and blood plasma. The nuclei of the pigment epithelium were preserved, the basal folds of the plasmolemma were clearly contoured. Small phagosomes were located in the cytoplasm of the pigment epithelium in one or two rows. The apical microvilli of the pigment epithelium were preserved, the interphotoreceptor space was hermetic. The membrane discs of the outer segments of the rods were clearly contoured. The cytoplasmic isthmus between the outer and inner segments of photoreceptors was intact. The outer boundary membrane was intensively osmophilic, preserved. Photoreceptor nuclei in the outer nuclear layer, clearly contoured. The synaptic zone of the outer reticular layer contained synaptic membranes and synaptic vesicles. The nuclei of horizontal and bipolar cells, the nuclei of Mьller cells and the nuclei of amacrine cells were located in the inner nuclear layer. The lumens of the vessels of the inner reticular layer were not dilated, they contained single erythrocytes. Nuclei and perikaryons of ganglion cells were arranged in one or two rows. Cytoplasmic structures of large gangloinary cells were preserved.

The medaka mutant deficient in eyes shut homolog exhibits opsin transport defects and enhanced autophagy in retinal photoreceptors.

Eyes shut homolog (EYS) encodes a proteoglycan and the human mutation causes retinitis pigmentosa type 25 (RP25) with progressive retinal degeneration. RP25 most frequently affects autosomal recessive RP patients with many ethnic backgrounds. Although studies using RP models have facilitated the development of therapeutic medications, Eys has been lost in rodent model animals. Here we examined the roles for Eys in the maintenance of photoreceptor structure and function by generating eys-null medaka fish using the CRISPR-Cas9 system. Medaka EYS protein was present near the connecting cilium of wild-type photoreceptors, while it was absent from the eys-/- retina. The mutant larvae exhibited a reduced visual motor response compared with wild-type. In contrast to reported eys-deficient zebrafish at the similar stage, no retinal cell death was detected in the 8-month post-hatching (8-mph) medaka eys mutant. Immunohistochemistry showed a significant reduction in the length of cone outer segments (OSs), retention of OS proteins in the inner segments of photoreceptors, and abnormal filamentous actin network at the base of cone OSs in the mutant retina by 8 mph. Electron microscopy revealed aberrant structure of calyceal processes, numerous vesiculation and lamellar interruptions, and autophagosomes in the eys-mutant cone photoreceptors. In situ hybridization showed an autophagy component gene, gabarap, was ectopically expressed in the eys-null retina. These results suggest eys is required for regeneration of OS, especially of cone photoreceptors, and transport of OS proteins by regulating actin filaments. Enhanced autophagy may delay the progression of retinal degeneration when lacking EYS in the medaka retina.

Retinal clinical and morphofunctional changes in high myopia in combination with age-related macular degeneration of different stages

Purpose: an analysis of clinical and morphofunctional changes of the retina in high myopia combined with age-related macular degeneration (AMD) of various stages.Materials and methods. We examined 45 patients (87 eyes, mean age 60 years) with high myopia (ave. spherical equivalent (SE) of refraction -11.0 D [-15.0; -7.125]) and the “dry” form of AMD, categories AREDS 1, 2, 3. Additionally, we formed three control groups of the same age range: group 1 consisted of 30 healthy subjects (58 eyes) with a SE between -0.25 D and +0.5 D and no retinal changes; group 2 included 20 patients (38 eyes) with isolated high myopia (SE +0.5 D and no retinal changes; group 2 included 20 patients (38 eyes) with isolated high myopia (SE ³ 6.5 D) and group 3 included another 20 patients (36 eyes) with the “dry” AMD form (AREDS 2, 3). We evaluated the best corrected visual acuity (BCVA), indicators of retinal photosensitivity (MD, PSD) according to computer perimetry data, and morphological characteristics: central retinal thickness (CRT), the anteroposterior axis of the eyeball, the condition of the macular region of the retina according to optical coherence tomography (OCT) in the β-scan mode and autofluorescence (AF).Results: in case of the combined pathology, we detected a reliable reduction of average BCVA to the level of 0.5 [0.3; 0.7] (p &lt; 0.001) and a reduced factor of retinal photosensitivity as compared to the control: MD to -4.36 dB (р&lt;0.001), PSD to 2.97 dB (р &lt; 0.001). CRT was 235 μm (p = 0.122), which showed no statistically significant differences to the control. Morphological changes of the retina corresponded to high myopia and AMD: a dome-shaped profile, lacquer cracks, paravascular retinal microcysts, paravascular lamellar ruptures; myopic maculopathy in the form of an epiretinal membrane, vitreomacular traction due to incomplete vitreoretinal cleavage, myopic foveoshisis; patchy chorioretinal atrophy, areas of diffuse RPE atrophy, damage of the junction line of the outer and inner segments of photoreceptors. The increase in the number and size of drusen depended on the stage of AMD. Normal autofluorescence of the fundus was absent. Pathological AF included minimal changes patterned as focal hypo- and hyperautofluorescence, reticular pattern, focal pattern, linear pattern, lace-like pattern, areas of geographic atrophy with pronounced hypoautofluorescence.Conclusion. Changes in OCT and visual field parameters (MD, PSD) in comorbid pathology (AMD combined with high myopia) were revealed. The morphofunctional indicators were compared for different AMD stages, and the diagnostic significance of AF was established.

Visible Light Optical Coherence Tomography Reveals the Relationship of the Myoid and Ellipsoid to Band 2 in Humans.

PurposeWe employ visible light optical coherence tomography (OCT) to investigate the relationship between the myoid, ellipsoid, and band 2 in the living human retina. Rather than refute existing theories, we aim to reveal new bands and better delineate the structures at hand.MethodsAn upgraded spectral/Fourier domain visible light OCT prototype, with 1.0-µm axial resolution, imaged 13 eyes of 13 young adult human subjects (23–40 years old) without a history of ocular pathology. The external limiting membrane (band 1) and band 2 edges were segmented. Reflectivity was examined along the inner segment (IS), defined as extending from band 1 to the band 2 center, and within band 2 itself.ResultsImages highlight a nearly continuously resolved extrafoveal internal limiting membrane, the peripheral single-cell thick ganglion cell layer, and the peripheral photoreceptor axonal fiber layer, a peripheral division of band 2 into bands 2a and 2b, and a reflectivity-based division of the IS into “m” and “e” zones.DiscussionTopography and transverse intensity variations of the outermost band 2b suggest an association with rods. The “m” and “e” zone border is consistent with the myoid–ellipsoid boundary, even recapitulating the well-documented distribution of mitochondria throughout the IS at the foveal center. Theories of outer retinal reflectivity in OCT must adequately explain these observations.Translational RelevanceFindings support that band 2 does partially overlap with the ellipsoid in transversally averaged OCT images due to photoreceptor IS length dispersion but argue that the inner ellipsoid must be inner to band 2, as suggested by prior quantitative measurements.

Ablation of pigment epithelium‐derived factor receptor, PEDF‐R, causes photoreceptor degeneration

Photoreceptor cells produce a receptor protein for pigment epithelium‐derived factor (PEDF‐R), which is encoded by the PNPLA2 gene of the patatin‐like phospholipase domain‐containing 2 family. PEDF‐R is a membrane‐linked lipase detected in the inner segments of photoreceptors. We aim to reveal the physiological role of PEDF‐R in photoreceptors by characterizing CRISPR Pnpla2 knock‐out mouse lines.CRISPR‐derived Pnpla2 knock‐out mouse lines were generated in a C57BL/6 and rd8 free background. RT‐PCR was performed from dissected retinas. Mice were evaluated for fundoscopy, electroretinography and angiography. Organs of the thorax were harvested and imaged using a LEICA microscope. Plasma was collected for lipid analyses. Eyes were enucleated and processed for histology, immunofluorescence, confocal microscopy, and transmission electron microscopy. Pnpla2‐/‐ mice had undetectable retinal Pnpla2 expression levels, enlarged whiter hearts, and lower plasma free fatty acids and triglycerides levels than their Pnpla2+/+ littermate controls. Their retinal pigment epithelial cells accumulated lipid droplets and their photoreceptors were deformed. Fundi of Pnpla2+/‐ eyes had white spots. The optic nerve area of Pnpla2‐/‐ and Pnpla2+/‐ mice had an excess of pigment. The a‐wave in Pnpla2‐/‐and Pnpla2+/‐ mice, and b‐wave in Pnpla2+/‐ mice were attenuated relative to controls. Retinal rhodopsin and opsin gene expression of Pnpla2‐/‐and Pnpla2+/‐ were lower than in controls. The immunofluorescent intensities of rhodopsin and opsin antibodies decreased in Pnpla2+/‐and Pnpla2‐/‐ photoreceptors relative to controls. The immunofluorescence of PKCα and synaptophysin antibodies (markers for bipolar cells and ribbon synapse) in the Pnpla2+/‐ retinas were lower than in controls. Ablation of Pnpla2 in mice causes malformation of photoreceptors and affects photoreceptor performance, identifying PEDF‐R as an important component for photoreceptor structure and function. These findings suggest that the absence of PEDF‐R in photoreceptor cells interrupts PEDF neurotrophic action, thereby heightening degeneration in the mice.

Evaluation of lead toxicity on the retina of pregnant rats and their pups: the possible ameliorative role of pomegranate juice

Background: Lead (Pb) exposure even at a low dose can induce functional and structural impairments in both humans and experimental animals. The present study evaluated the potential ameliorative role of pomegranate juice (PJ), as a powerful antioxidant fruit against histopathological and ultrastructural changes caused by Pb in the retina of pregnant rats and their neonates. Methods: 24 pregnant female rats were selected and randomly divided into four groups (n=6): control, PJ supplemented (100 μL PJ), Pb treated (18.5 mg / kg B.Wt), and Pb co-supplemented alternatively with PJ group. After birth, the mother rats, as well as their neonates at different ages (7, 14, and 21 days old), were dissected and the eyes were removed for histological, ultrastructural, and immunohistochemical investigation of the retina. Results: The obtained results revealed deleterious histological and ultrastructural lesions in all retinal cell layers of Pb-treated female rats and their offspring. Such lesions included hypertrophied cells of retinal pigmented epithelium (RPE) with pronounced vacuolated mitochondria and fragmented Bruch's membrane. The outer and inner segments of photoreceptors appeared fragmented and detached from the RPE. Additionally, the outer nuclear layer (ONL) and inner nuclear layer (INL) appeared disorganized with vacuolated cytoplasm and pyknotic nuclei. The immunohistochemical results displayed glial fibrillary acidic protein (GFAP) weak expression and P53 strong expression in the retinal sections of the Pb-treated group of female rats and their neonates if compared with control. Conclusions: PJ successfully alleviated the deleterious histological and ultrastructural as well as immunohistochemical changes induced by lead.

New COL6A6 Variant Causes Autosomal Dominant Retinitis Pigmentosa in a Four-Generation Family.

PurposeTo report that variants in the gene for a large lamina basal component protein, COL6A6 (collagen type VI alpha 6 chain, Col6α6), linked to chromosome 3p22.1 causes retinitis pigmentosa (RP) in patients with autosomal dominant transmission (adRP).MethodsA positional-cloning approach, whole exome sequencing, and modeling were used. The proband and several affected family members have been phenotyped and followed for over 12 years.ResultsA heterozygous missense variant, c.509C>G (p. Ser170Cys) in exon 2 of COL6A6 (comprised of 36 exons and 2236 amino acids), was observed in a four- generation family and is likely to cause the adRP phenotype. It was identified in 10 affected members. All affected family members had a distinct phenotype: late-onset rod cone dystrophy, with good retained visual acuity, until their late 70s. Immunohistochemistry of human retina showed a dot-like signal at the base of the inner segments of photoreceptors and outer plexiform layer (OPL). The structural modeling of the N7 domain of Col6α6 suggests that the mutant might result in the abnormal cellular localization of collagen VI or malformation of collagen fibers resulting in the loss of its unique filament structure.Conclusions COL6A6 is widely expressed in human tissues and evolutionary conserved. It is thought to interact with a range of extracellular matrix components. Our findings suggest that this form of RP has long-term useful central visual acuity and a mild progression, which are important considerations for patient counseling.

Длина наружных сегментов фоторецепторов как предиктор высоких зрительных функций при регматогенной отслойке сетчатки

Introduction. The integrity of photoreceptor's inner segment/outer segment connection plays great importance in predicting visual acuity in eyes with retinal pathology. However, even optical coherence tomographic study showed the intact of retinal layers, including photoreceptor's inner segment/outer segment line, after surgery due to rhegmatogenous retinal detachment (RRD), low visual acuity is observed. Purpose. to identify predictors of high visual acuity in the foveolar zone in patients after successful RRD repair according to SD-OCT. Material and methods. Group 1 consisted of 20 cases – eyes after successful primary RRD repair performed through pars plana vitrectomy using silicone oil tamponade (1300 cSt), followed by removal of silicone oil with a replacement for sterile air. Group 2 – control, followed eyes without ophthalmopathology and visualisation of foveolar bulge according to OCT. All patients underwent a standard ophthalmological examination and OCT on the 30th day after silicone oil removal. OCT examination was performed by Retina Map and Cross Line modes. The lengths of the outer segments of photoreceptors, inner segments of photoreceptors and the outer nuclear layer of the layer were measured in manual mode. Retina Map was used to measure retinal foveolar thickness. Results. During the study, the data of the foveolar thickness of the retina, the outer nuclear layer and the length of the outer segment of photoreceptors in the main group showed a significant decrease in comparison with the control group (p=0.002, p=0.006, p=0.02, respectively). In this case, a strong correlation was obtained only between the length of the outer segments of photoreceptors and visual acuity (r=0.68). Conclusion. The length of the outer segments of the cones in the central retinal area, or foveolar bulge, should considers a predictor of high visual acuity twostage surgical treatment of primary RRD using silicone oil. Key words: retinal detachment, foveolar bulge, ellipsoid zone, vitrectomy, OCT.

ADIPOR1 deficiency-induced suppression of retinal ELOVL2 and docosahexaenoic acid levels during photoreceptor degeneration and visual loss

Lipid metabolism-related gene mutations can cause retinitis pigmentosa, a currently untreatable blinding disease resulting from progressive neurodegeneration of the retina. Here, we demonstrated the influence of adiponectin receptor 1 (ADIPOR1) deficiency in retinal neurodegeneration using Adipor1 knockout (KO) mice. Adipor1 mRNA was observed to be expressed in photoreceptors, predominately within the photoreceptor inner segment (PIS), and increased after birth during the development of the photoreceptor outer segments (POSs) where photons are received by the visual pigment, rhodopsin. At 3 weeks of age, visual function impairment, specifically photoreceptor dysfunction, as recorded by electroretinography (ERG), was evident in homozygous, but not heterozygous, Adipor1 KO mice. However, although photoreceptor loss was evident at 3 weeks of age and progressed until 10 weeks, the level of visual dysfunction was already substantial by 3 weeks, after which it was retained until 10 weeks of age. The rhodopsin mRNA levels had already decreased at 3 weeks, suggesting that reduced rhodopsin may have contributed to early visual loss. Moreover, inflammation and oxidative stress were induced in homozygous KO retinas. Prior to observation of photoreceptor loss via optical microscopy, electron microscopy revealed that POSs were present; however, they were misaligned and their lipid composition, including docosahexaenoic acid (DHA), which is critical in forming POSs, was impaired in the retina. Importantly, the expression of Elovl2, an elongase of very long chain fatty acids expressed in the PIS, was significantly reduced, and lipogenic genes, which are induced under conditions of reduced endogenous DHA synthesis, were increased in homozygous KO mice. The causal relationship between ADIPOR1 deficiency and Elovl2 repression, together with upregulation of lipogenic genes, was confirmed in vitro. Therefore, ADIPOR1 in the retina appears to be indispensable for ELOVL2 induction, which is likely required to supply sufficient DHA for appropriate photoreceptor function and survival.

Restoration of Foveal Bulge after Resolution of Diabetic Macular Edema with Coexisting Serous Retinal Detachment.

Purpose To evaluate the impact of restoration of foveal bulge (FB) in optical coherence tomography (OCT) images on visual acuity after resolution of diabetic macular edema with coexisting serous retinal detachment (SRD-DME). Methods A total of 52 eyes with resolved SRD-DME and an intact ellipsoid zone at the central fovea were included. All eyes underwent best-corrected visual acuity (BCVA) examination and OCT scanning at baseline and follow-up visits (1, 3, and 6 months). The eyes were divided into two groups according to the presence of FB at 6 months. BCVA, central foveal thickness (CFT), height of SRD (SRDH), outer nuclear layer (ONL) thickness, photoreceptor inner segment (PIS), and outer segment (POS) length were compared between the two groups. Results A FB was found in 25 of 52 (48%) eyes at 6 months. The FB (+) group had lower SRDH at baseline, and better BCVA, longer POS length at 6 months (all P < 0.05). There was no significant difference in the CFT, ONL thickness, and PIS length at 6 months between the two groups (all P > 0.05). More eyes in the FB (+) group had complete SRD resolution at 1 month (P = 0.009) and 3 months (P = 0.012). Eyes with complete SRD resolution at 1 month (P = 0.009) or 3 months (P = 0.012) were more likely to have a FB at 6 months. Conclusions The Presence of the FB is associated with better BCVA after resolution of SRD-DME. Eyes with lower baseline SRDH or faster SRD resolution are more likely to have a FB at 6 months.

Retinal toxicity study of intravitreal ganciclovir in albino rabbit

Objective: To elevated the retinal toxicity of intravitreal ganciclovir in albino rabbit eyes. Methods: Experimental study. Twenty-four New Zealand albino rabbits (forty-eight eyes) were divided into four groups by random. Three groups were prepared for ganciclovir experiment, named A, B, C. Each group received intravitreal injection ganciclovir dose at 400 μg/0.05 ml, 2 mg/0.05 ml and 5 mg/0.05 ml respectively. The other group named D served as a control accepted intravitreal injection 0.9% normal saline 0.1 ml. Before and after 1, 2 and 4 weeks, flicker full field electroretina gram (ERG) was recorded. After 1, 2 and 4 weeks light and electron microscopic tests were recorded for further toxicity study. Results: There was significant difference in amplitude of maximal combined response a wave in one week(χ(2)=8.319, P=0.04), and pairwise comparison the 5 mg group (140.50 μV) was significantly lower than the control group (165.00 μV) (χ(2)=-2.830, P=0.028). Maximal combined response b wave in four weeks(χ(2)=-10.626, P=0.014), and pairwise comparison the 5 mg group (261.50 μV) was significantly lower than the control group (398.00 μV) (χ(2)=-2.973, P=0.018). 30 Hz flicker response in one, two and four weeks(χ(2)=17.589, 8.225, 8.997, P=0.001, 0.042, 0.02), and pairwise comparison the 5 mg group (71.3μV, 106.00μV, 63.60μV) was significantly lower than the control group (118.50μV, 129.00μV, 116.50μV) (χ(2)=-4.142, -2.826, -2.713, P=0.000, 0.028, 0.040). There was no histologic retinal toxicity evidence of group 400 μg and control group observed by light microscopy in any stage of the study. Histologic changes of group 2 mg four week later, group 5 mg two and four week later include inner nuclear layer loose arranged, nuclear of ganglia were widened and outer plexiform layer stained less in four week later. By electron microscopic observation, the ultrastructure of retina changed to different degrees and became worse in each experimental group with significant mitochondrial swelling and hydropic changes were seen in the inner segments of photoreceptors, loosely arranged and disordered in the outer segment of photoreceptors four weeks later. Conclusions: The retinal function and morphology were normal in group 400 μg. Group 2 mg and 5 mg had retinal toxicity, and 5 mg was more severe. Therefore, the clinical application of ganciclovir in the treatment of acute retinal necrosis (ARN) should select the minimum effective dose to avoid the occurrence of retinal toxicity. (Chin J Ophthalmol, 2020, 56:279-285).

Immunohistochemical localization of alpha-synuclein in the retina of some nocturnal and diurnal animals

ABSTRACTAlthough alpha-synuclein has been reported to participate in neurodegenerative diseases, the actual normal biological function of alpha-synuclein remains unclear. I investigated the correlation of alpha-synuclein expression with nocturnal and diurnal activity for various species. Hematoxylin and eosin staining, periodic acid-Schiff’s reaction (PAS) and immunohistochemistry of alpha-synuclein expression were performed for the retinas of diurnal, nocturnal, nocturnal with diurnal activity species. I found different intensity of alpha-synuclein expression in the retinal layers. I found alpha-synuclein expression in the outer segment of the photoreceptor layer in the diurnal studied species and absence of alpha-synuclein expression in the compartments of photoreceptor layer in the retina of nocturnal species. I found localization of alpha-synuclein in the inner and outer segments of photoreceptors of the retina of nocturnal with diurnal activity species. The retinas of diurnal animals exhibited glycogen in the paraboloid structure in the inner segment of the photoreceptor layer. The retinas of nocturnal and nocturnal with diurnal activity species were devoid of glycogen in the photoreceptor layer. I conclude that the function of alpha-synuclein is more related to diurnal than to nocturnal species.

Hunting for the Adhesion Molecule, Retinoschisin, in Retina using Cemovis

In studying biologically relevant molecules, the ultimate aim is to visualize them in their native environment. One technique that has the potential to resolve individual molecules in cells and tissues is cryo-electron microscopy of vitreous sections (CEMOVIS) combined with tomography. We are interested in revealing the disposition of the retinal adhesion protein, retinoschisin (RS1), within the retina. Immuno-fluorescence and immuno-electron microscopy showed that RS1 is abundant in the intercellular spaces between the inner segments of photoreceptors, and between bipolar cells. Loss-of-function mutations in RS1 cause X-linked retinoschisis (XLRS), a debilitating disease associated with the formation of retinal cavities or cysts (schisis) and vision loss in young males. We solved the structure to 4.1 Å by cryo-electron microscopy (cryoEM), a 16-mer composed of two octameric rings with a total weight of ∼380 kDa. From this structure it is clear that many mutations in the subunit interfaces would preclude assembly of the rings. However, other mutation sites are exposed at the periphery and it was not evident how they would cause disease. In further cryoEM experiments, we observed that RS1 double rings self-assemble into extensive branched networks, suggesting a mechanism for its adhesive function. To ascertain whether this assembly also occurs in situ, we are examining mouse retinal tissue using CEMOVIS and cryo-electron tomography. We obtained images of 50 nm cryosections that show clear distinction of microtubular protofilaments separated by ∼5 nm. This resolution is clearly sufficient to see the RS1 double ring and whether it assembles into networks in the intercellular space between photoreceptors and bipolar cells.

Biallelic mutations in USP45, encoding a deubiquitinating enzyme, are associated with Leber congenital amaurosis

BackgroundLeber congenital amaurosis (LCA) is the earliest and most severe form of inherited retinal dystrophies. In approximately 56% of Chinese probands, genetic defects can be detected in known LCA-causing genes....

Ellipsoid Zone Change According to Glaucoma Stage Advancement

To compare retinal photoreceptor ellipsoid zone (EZ) intensity between normal eyes and those with different stages of glaucoma. Retrospective cross-sectional study. The study included 37 normal, 38 preperimetric glaucoma, 39 mild-to-moderate glaucoma (visual field [VF] mean deviation [MD]:-7.7 ± 2.0 dB), and 36 severe glaucoma eyes (VF MD:-17.8 ± 3.2 dB). The subjects underwent high-resolution horizontal and vertical line scans through the fovea by spectral-domain optical coherence tomography (SD-OCT). Image processing software was employed to quantify the intensity of the first and second hyperreflective bands corresponding with the external limiting membrane (ELM) and EZ. In order to account for the brightness variation among scans, the relative EZ intensity as the ratio of the second to first reflective band (EZ/ELM) was determined. The relative EZ intensity in severe glaucoma eyes was significantly lower than in mild-to-moderate glaucoma eyes (2.46 ± 0.38 vs 3.15 ± 0.43, P < .001); also, it was lower in mild-to-moderate than in preperimetric glaucoma eyes (3.15 ± 0.43 vs 3.86 ± 0.44, P < .001). However, the comparison between preperimetric glaucoma and normal eyes showed no significant difference (3.86 ± 0.44 vs 4.06 ± 0.40, P= .751). In 75 glaucomatous eyes with VF defect, there was a significant correlation between relative EZ intensity and VF MD (r= 0.83 and P < .001). According to SD-OCT, relative EZ intensity reduction occurs in the mild-to-moderate and severe glaucoma stages. These findings suggest, at least provisionally, that in the course of glaucoma progression, mitochondrial changes in the inner segments of photoreceptors occur. Further investigation is warranted to evaluate the potential clinical significance of EZ intensity reduction in glaucoma.