Retina Of Eye Research Articles

DEEP LEARNING APPROACHES FOR MULTI-CLASS DISEASE DETECTION AND CLASSIFICATION IN RETINAL IMAGES

Many techniques are designed to increase accuracy diagnoses of diseases in retinal images such as hypertensive retinopathy. Convolutional neural networks (CNN) have been employed in various techniques to segment blood vessels in retinal images. These techniques sometimes fail to effectively segment the blood vessels of retina of eye and produce extra noise and we have with this drawback, we present a technique to detect blood vessels in retina of eye images using thousands of blocks (patches) from each of the image. This technique is on a CNN where it contains four convolutional layers followed by relu, max pooling four layers, two layers are fully connected and one layer is the softmax for segmenting blood vessels.

Controlling autoimmune diabetes onset by targeting Protease-Activated Receptor 2

BackgroundType 1 diabetes (T1D) is a challenging autoimmune disease, characterized by an immune system assault on insulin-producing β-cells. As insulin facilitates glucose absorption into cells and tissues, β-cell deficiency leads to elevated blood glucose levels on one hand and target-tissues starvation on the other. Despite efforts to halt β-cell destruction and stimulate recovery, success has been limited. Our recent investigations identified Protease-Activated Receptor 2 (Par2) as a promising target in the battle against autoimmunity. We discovered that Par2 activation’s effects depend on its initial activation site: exacerbating the disease within the immune system but fostering regeneration in affected tissue. MethodsWe utilized tissue-specific Par2 knockout mice strains with targeted Par2 mutations in β-cells, lymphocytes, and the eye retina (as a control) in the NOD autoimmune diabetes model, examining T1D onset and β-cell survival. ResultsWe discovered that Par2 expression within the immune system accelerates autoimmune processes, while its presence in β-cells offers protection against β-cell destruction and T1D onset. This suggests a dual-strategy treatment for T1D: inhibiting Par2 in the immune system while activating it in β-cells, offering a promising strategy for T1D. ConclusionsThis study highlights Par2's potential as a drug target for autoimmune diseases, particularly T1D. Our results pave the way for precision medicine approaches in treating autoimmune conditions through targeted Par2 modulation.

Giant retinal pigment epithelium tears with membranous nephropathy: a case report and literature review

BackgroundKidney and eye diseases may be closely linked. Tears of the retinal pigment epithelium (RPE) have been reported to be related to kidney diseases, such as IgA nephropathy and light-chain deposition disease. However, pigment epithelium tears associated with membranous nephropathy have not been reported or systematically analysed.Case presentationA 68-year-old man presented with decreased right eye visual acuity. Optical coherence tomography (OCT) revealed cystic macular edema, localized serous detachment of the retina and loss of the outer retinal structure in the right eye and retinal pigment epithelium detachment (PED) combined with serous detachment of the retina in the left eye. Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) revealed giant RPE tears in the right eye and exudative age-related macular degeneration in the left eye. The patient also suffered from severe membranous nephropathy-autoimmune glomerulonephritis. Renal biopsy immunofluorescence revealed a roughly granular pattern, with immunoglobulin G (IgA), immunoglobulin G (IgG), IgM, complement C3(Components 3), λ light chain and κ light chain subepithelial staining.ConclusionsIt is hypothesized that severe membranous nephropathy caused immune complex deposition on the surface of Bruch membrane, resulting in weakened adhesion between the RPE and Bruch membrane and impaired RPE pump function, combined with age-related macular degeneration, leading to giant RPE tears in the right eye. Close attention should be given to the ocular condition of patients with membranous nephropathy to facilitate timely treatment and avoid serious consequences.

Peripheral Choroidal Response to Localized Defocus Blur: Influence of Native Peripheral Aberrations.

This study aims to examine the short-term peripheral choroidal thickness (PChT) response to signed defocus blur, both with and without native peripheral aberrations. This examination will provide insights into the role of peripheral aberration in detecting signs of defocus. The peripheral retina (temporal 15°) of the right eye was exposed to a localized video stimulus in 11 young adults. An adaptive optics system induced 2D myopic or hyperopic defocus onto the stimulus, with or without correcting native peripheral ocular aberrations (adaptive optics [AO] or NoAO defocus conditions). Choroidal scans were captured using Heidelberg Spectralis OCT at baseline, exposure (10, 20, and 30minutes), and recovery phases (4, 8, and 15minutes). Neural network-based automated MATLAB segmentation program measured PChT changes from OCT scans, and statistical analysis evaluated the effects of different optical conditions over time. During the exposure phase, NoAO myopic and hyperopic defocus conditions exhibited distinct bidirectional PChT alterations, showing average thickening (10.0 ± 5.3µm) and thinning (-9.1 ± 5.5µm), respectively. In contrast, induced AO defocus conditions did not demonstrate a significant change from baseline. PChT recovery to baseline occurred for all conditions. The unexposed fovea did not show any significant ChT change, indicating a localized ChT response to retinal blur. We discovered that the PChT response serves as a marker for detecting peripheral retinal myopic and hyperopic defocus blur, especially in the presence of peripheral aberrations. These findings highlight the significant role of peripheral oriented blur in cueing peripheral defocus sign detection.

Bio-inspired “Self-denoising” capability of 2D materials incorporated optoelectronic synaptic array

In in-sensor image preprocessing, the sensed image undergoes low level processing like denoising at the sensor end, similar to the retina of human eye. Optoelectronic synapse devices are potential contenders for this purpose, and subsequent applications in artificial neural networks (ANNs). The optoelectronic synapses can offer image pre-processing functionalities at the pixel itself—termed as in-pixel computing. Denoising is an important problem in image preprocessing and several approaches have been used to denoise the input images. While most of those approaches require external circuitry, others are efficient only when the noisy pixels have significantly lower intensity compared to the actual pattern pixels. In this work, we present the innate ability of an optoelectronic synapse array to perform denoising at the pixel itself once it is trained to memorize an image. The synapses consist of phototransistors with bilayer MoS2 channel and p-Si/PtTe2 buried gate electrode. Our 7 × 7 array shows excellent robustness to noise due to the interplay between long-term potentiation and short-term potentiation. This bio-inspired strategy enables denoising of noise with higher intensity than the memorized pattern, without the use of any external circuitry. Specifically, due to the ability of these synapses to respond distinctively to wavelengths from 300 nm in ultraviolet to 2 µm in infrared, the pixel array also denoises mixed-color interferences. The “self-denoising” capability of such an artificial visual array has the capacity to eliminate the need for raw data transmission and thus, reduce subsequent image processing steps for supervised learning.

Suprachoroidal gene transfer with nonviral nanoparticles in large animal eyes.

Suprachoroidal nonviral gene therapy with biodegradable poly(β-amino ester) nanoparticles (NPs) provides widespread expression in photoreceptors and retinal pigmented epithelial (RPE) cells and therapeutic benefits in rodents. Here, we show in a human-sized minipig eye that suprachoroidal injection of 50 μl of NPs containing 19.2 μg of GFP expression plasmid caused GFP expression in photoreceptors and RPE throughout the entire eye with no toxicity. Two weeks after injection of 50, 100, or 200 μl, there was considerable within-eye and between-eye variability in expression that was reduced 3 months after injection of 200 μl and markedly reduced after three suprachoroidal injections at different locations around the eye. Reduction of bacterial CpG sequences in the expression plasmid resulted in a trend toward higher expression. These data indicate that nonviral suprachoroidal gene therapy with optimized polymer, expression plasmid, and injection approach has potential for treating photoreceptors throughout the entire retina of a human-sized eye.

Orbital cellulitis with exudative retinal detachment: A rare finding

Abstract Orbital cellulitis is a rare cause of exudative retinal detachment (ERD). We hereby present a case of orbital cellulitis associated with ERD from North India. A 42-year-old man presented with features of orbital cellulitis in the left eye for 3 days. An ERD lesion was found in the superior-temporal quadrant of the retina of the same eye. Investigations were performed; however, the cause of orbital cellulitis could not be found. Systemic antibiotics were started, leading to improved orbital cellulitis and resolution of ERD. Orbital cellulitis can be treated with systemic antibiotics. The cure of underlying disease leads to the resolution of ERD.

Posterior segment parameters after uveitic cataract surgery: A prospective study with 1-year results

PurposeTo evaluate the changes in posterior segment after uncomplicated cataract surgery in uveitic patients. MethodsRetinal nerve fiber layer thickness (RNFLT), ganglion cell layer thickness (GCLT), central macular thickness (CMT), and choroidal thickness (CT) of 38 eyes of 28 patients were measured pre- and postoperatively on day 1, week 1, and month 1, 3, 6, 9, and 12. ResultsThe RNFLT increased after surgery. Although the measurements taken were higher than the baseline CMT at all postoperative times, no significant difference was detected between the paired comparisons. The GCLT was found to be higher than the baseline value in all quadrants at the 12th month. A decrease in CT was observed at 5 measured points on the 1st day compared to the baseline. ConclusionDuring the 1-year follow-up, the effect of cataract surgery on the retina and choroid in uveitic eyes was most evident at the postoperative month 1.

The E3 ligase SMURF1 stabilizes p27 via UbcH7 catalyzed K29-linked ubiquitin chains to promote cell migration SMURF1-UbcH7 K29 ubiquitination of p27 and cell migration

Ubiquitination is a key regulator of protein stability and function. The multifunctional protein p27 is known to be degraded by the proteasome following K48-linked ubiquitination. However, we recently reported that when the ubiquitin conjugating enzyme UbcH7 (UBE2L3) is overexpressed, p27 is stabilized and cell cycle is arrested in multiple diverse cell types including eye lens, retina, HEK-293 and HELA cells. But the ubiquitin ligase associated with this stabilization of p27 remained a mystery. Starting with an in vitro ubiquitination screen, we identified RSP5 as the yeast E3 ligase partner of UbcH7 in the ubiquitination of p27. Screening of the homologous human NEDD4 family of E3 ligases revealed that SMURF1, but not its close homolog SMURF2, stabilizes p27 in cells. We found that SMURF1 ubiquitinates p27 with K29O but not K29R or K63O ubiquitin in vitro, demonstrating a strong preference for K29 chain formation. Consistent with SMURF1/UbcH7 stabilization of p27, we also found that SMURF1, UbcH7, and p27 promote cell migration, whereas knockdown of SMURF1 or UbcH7 reduces cell migration. We further demonstrated colocalization of SMURF1/p27 and UbcH7/p27 at the leading edge of migrating cells. In sum, these results indicate that SMURF1 and UbcH7 work together to produce K29-linked ubiquitin chains on p27, resulting in stabilization of p27 and promoting its cell-cycle independent function of regulating cell migration.

Association between deficient levels of vitamin D and the occurrence of selected retinal diseases

Introduction and Purpose:
 Vision originates in the eye's retina, a complex structure essential for processing visual information. The connection between nutritional inadequacy, particularly vitamin deficiencies, and overall health, including ocular health, has long been acknowledged. Recent studies highlight the potential impact of vitamin D, a crucial nutrient, on retinal health. The aim is to investigate the association between low levels of vitamin D and retinal diseases like age-related macular degeneration (AMD) and diabetic retinopathy (DR), and to evaluate the potential benefits of vitamin D supplementation or lifestyle changes for at-risk patients.
 Description of the State of Knowledge:
 AMD, a significant cause of blindness in the elderly, involves factors like oxidative stress and inflammation. Various stages of AMD require different treatments, with limited options for advanced stages. DR, a complication of diabetes, leads to conditions such as retinal ischemia and neovascularization. Both conditions are potentially influenced by vitamin D levels. Studies show mixed results regarding the impact of vitamin D on these diseases. Some suggest lower levels may increase risk, while others report no significant effect or even contradictory findings.
 Conclusions:
 While some studies indicate a potential association between low vitamin D levels and the occurrence of retinal diseases, discrepancies exist in the findings. Lower vitamin D concentrations may be linked to a higher frequency of AMD and DR, but the evidence is not consistent across all studies. Therefore, a more in-depth exploration of this subject is warranted to draw conclusive insights. It is crucial to consider supplementation or dietary changes in cases of vitamin D deficiency, given its potential impact on systemic health.

Synchronous functional magnetic resonance eye imaging, video ophthalmoscopy, and eye surface imaging reveal the human brain and eye pulsation mechanisms

The eye possesses a paravascular solute transport pathway that is driven by physiological pulsations, resembling the brain glymphatic pathway. We developed synchronous multimodal imaging tools aimed at measuring the driving pulsations of the human eye, using an eye-tracking functional eye camera (FEC) compatible with magnetic resonance imaging (MRI) for measuring eye surface pulsations. Special optics enabled integration of the FEC with MRI-compatible video ophthalmoscopy (MRcVO) for simultaneous retinal imaging along with functional eye MRI imaging (fMREye) of the BOLD (blood oxygen level dependent) contrast. Upon optimizing the fMREye parameters, we measured the power of the physiological (vasomotor, respiratory, and cardiac) eye and brain pulsations by fast Fourier transform (FFT) power analysis. The human eye pulsated in all three physiological pulse bands, most prominently in the respiratory band. The FFT power means of physiological pulsation for two adjacent slices was significantly higher than in one-slice scans (RESP1 vs. RESP2; df = 5, p = 0.045). FEC and MRcVO confirmed the respiratory pulsations at the eye surface and retina. We conclude that in addition to the known cardiovascular pulsation, the human eye also has respiratory and vasomotor pulsation mechanisms, which are now amenable to study using non-invasive multimodal imaging of eye fluidics.

Nanoparticles of Push-Pull Triphenylamine-Based Molecules for Light-Controlled Stimulation of Neuronal Activity.

Organic semiconductor materials with a unique set of properties are very attractive for interfacing biological objects and can be used for noninvasive therapy or detection of biological signals. Here, we describe the synthesis and investigation of a novel series of organic push-pull conjugated molecules with the star-shaped architecture, consisting of triphenylamine as a branching electron donor core linked through the thiophene π-spacer to electron-withdrawing alkyl-dicyanovinyl groups. The molecules could form stable aqueous dispersions of nanoparticles (NPs) without the addition of any surfactants or amphiphilic polymer matrixes with the average size distribution varying from 40 to 120 nm and absorption spectra very similar to those of human eye retina pigments such as rods and green cones. Variation of the terminal alkyl chain length of the molecules forming NPs from 1 to 12 carbon atoms was found to be an efficient tool to modulate their lipophilic and biological properties. Possibilities of using the NPs as light nanoactuators in biological systems or as artificial pigments for therapy of degenerative retinal diseases were studied both on the model planar bilayer lipid membranes and on the rat cortical neurons. In the planar bilayer system, the photodynamic activity of these NPs led to photoinactivation of ion channels formed by pentadecapeptide gramicidin A. Treatment of rat cortical neurons with the NPs caused depolarization of cell membranes upon light irradiation, which could also be due to the photodynamic activity of the NPs. The results of the work gave more insight into the mechanisms of light-controlled stimulation of neuronal activity and for the first time showed that fine-tuning of the lipophilic affinity of NPs based on organic conjugated molecules is of high importance for creating a bioelectronic interface for biomedical applications.

The Role of microRNAs Related to Apoptosis for N-Methyl-d-Aspartic Acid-Induced Neuronal Cell Death in the Murine Retina.

Glaucoma is one of the leading causes of acquired blindness and characterized by retinal ganglion cell (RGC) death. MicroRNAs are small noncoding RNAs that degrade their target mRNAs. Apoptosis is one of the common mechanisms leading to neuronal death in many neurodegenerative diseases, including glaucoma. In the present study, we identified microRNAs that modulate RGC death caused by the intravitreal injection of N-methyl-d-aspartic acid (NMDA). We found an upregulation of miR-29b and downregulation of miR-124 in the retina of the NMDA-injected eyes. The intravitreal injection of an miR-29b inhibitor 18 h before NMDA injection reduced RGC death and the downregulation of myeloid cell leukemia 1 (MCL-1), an anti-apoptotic factor, induced by intravitreal NMDA. The intravitreal injection of an miR-124 mimic 18 h before NMDA injection also reduced RGC death and the upregulation of B-cell/chronic lymphocytic leukemia lymphoma 2 (bcl-2)-associated X protein (Bax) and bcl-2 interacting protein (Bim), pro-apoptotic factors, induced by intravitreal NMDA. These data suggest that expressional changes in microRNA are involved in the excitotoxicity of RGCs, and that complement and/or inhibition of microRNA may be a potential therapeutic approach for the diseases related to the excitotoxicity of RGCs, such as glaucoma and retinal central artery occlusion.

Memory effect and coexistence of negative and positive photoconductivity in black phosphorus field effect transistor for neuromorphic vision sensors.

Black phosphorus (BP) field-effect transistors with ultrathin channels exhibit unipolar p-type electrical conduction over a wide range of temperatures and pressures. Herein, we study a device that exhibits mobility up to 100 cm2 V-1 s-1 and a memory window up to 1.3 μA. Exposure to a supercontinuum white light source reveals that negative photoconductivity (NPC) and positive photoconductivity (PPC) coexist in the same device. Such behavior is attributed to the chemisorbed O2 molecules, with a minor role of physisorbed H2O molecules. The coexistence of NPC and PPC can be exploited in neuromorphic vision sensors, requiring the human eye retina to process the optical signals through alerting and protection (NPC), adaptation (PPC), followed by imaging and processing. Our results open new avenues for the use of BP and other two-dimentional (2D) semiconducting materials in transistors, memories, and neuromorphic vision sensors for advanced applications in robotics, self-driving cars, etc.

Surgical treatment of retinal detachment complicated by a macular hole

Retinal detachment with a macular hole is a severe pathology leading to vision loss and disability of the patient. It is most frequently observed in myopes and causes severe damage of functional parameters of the retina. The pathogenesis of the disease is associated with tangential tractions of the inner limiting membrane and the posterior layers of the vitreous that affect the retina of the myopic eye. Modern ophthalmology uses a variety of approaches to the surgical treatment of the pathology. The final functional result primarily depends on how successful the macular hole closure and retinal reattachment are. To achieve this success, various techniques of subretinal fluid drainage can be used. The present literature review was conducted using the Pubmed search engine. We analyzed the articles published from 2000 to 2021. The analysis of research results showed the advantage of the peripheral method of drainage using a perfluoroorganic compound. This technique is relevant both in cases of the peripheral retinal tear and in subretinal fluid aspiration through the retinotomy. The peripheral method of drainage using a perfluoroorganic compound ensures a better functional outcome, which, in case of retinal detachment with a macular hole, mainly depends on the safety of the neuroreceptors of the central zone and the closure of the macular hole.

Evaluation of Central and Peripheral Retinal Vascular Changes in the Fellow Eyes of Patients with Unilateral Retinal Vein Occlusions

To evaluate the subtle peripheral retinal and macular vascular changes in the fellow eyes of patients with unilateral retinal vein occlusion (RVO). This retrospective study included 53 patients with unilateral RVO and 44 age-matched controls. The frequency of peripheral retinal vascular pathologies in both eyes was evaluated using high quality ultra-wide field fluorescein angiography (UWFFA). Macular vascular density, flow area, and foveal avascular zone measurements from optical coherence tomography angiography (OCTA) were analyzed together with laser flare photometry values in patients and controls. Peripheral retinal vascular pathologies were detected on UWFFA in the fellow eyes of 36 (67.9%) patients. No significant central vascular pathologies were detected on OCTA and there was no significant difference in OCTA parameters between the fellow eyes and the controls. Flare values did not differ significantly between the control and the fellow eyes. Two thirds of the fellow eyes of unilateral RVO patients had subtle peripheral retinal vascular changes, while there was no significant microvascular change detected with OCTA in the macula. This suggests that vascular changes caused by systemic vascular disorders probably first start in the peripheral retina of the fellow eyes of patients with RVO.

Short-Term and Long-Term Effects after Exposure to Ionizing Radiation and Visible Light on Retina and Retinal Pigment Epithelium of Mouse Eye

Short-Term and Long-Term Effects after Exposure to Ionizing Radiation and Visible Light on Retina and Retinal Pigment Epithelium of Mouse Eye

Study on maintenance of eyeball morphology by foldable capsular vitreous body in severe ocular trauma

ObjectivesTo explore the feasibility and safety of using a foldable capsular vitreous body (FCVB) in managing severe ocular trauma and silicone oil-dependent eyes.MethodologyThis is a retrospective study of 61 ocular trauma patients (61 eyes) who presented to the Department of Eye Emergency, Hebei Eye Hospital from May 1, 2018, to May 31, 2019, including 51 male patients (51 eyes) and 10 female patients (10 eyes) with an average age of 44.98 ± 14.60 years old. The oldest patient was 75 years old, and the youngest was 8 years old. These cases represented 51 eyes with severe eyeball rupture and 10 eyes with severe, complicated ocular trauma, which became silicone oil-dependent after the operation. These patients received FCVB implants, and data regarding their visual acuity, intraocular pressure, changes in eye axis, cornea, retina, and FCVB state were recorded after the operation.ResultsIn all patients, the FCVB was properly positioned and well supported with the retina. All 61 patients cleared a follow-up window of 1–36 months with no reports of important changes in their visual acuity. Among the patients, 91.8% reported normal intraocular pressure, the retinal reattachment rate reached 100%, and the eyeball atrophy control rate reached 100%. There was no report of rupture of the FCVB, allergies to silicone, intraocular infection, intraocular hemorrhage, silicone oil emulsification, or sympathetic ophthalmia.ConclusionsFoldable capsular vitreous bodies (FCVBs) designed to mimic natural vitreous bodies are suitable as long-term ocular implants that can provide sustained support for the retina without the need for any special postoperative postures. Their barrier function may effectively prolong the retention time of the tamponade and prevent various complications caused by direct contact of the eye tissues with the tamponade.

Evaluation of retinal angioarchitectonics by optical coherence angiography and its diagnostic value in functional amblyopia

AIM: This study aimed to evaluate the density parameters of the superficial and deep plexuses of the retina, choriocapillary layer, and avascular zone in eyes with amblyopia of various origins and paired fellow eyes.
 MATERIAL AND METHODS: The study included 40 patients aged 616 (mean, 8.723.04) years. All patients were divided into 2 groups: group 1 included amblyopic, dysbinocular, and anisometropic eyes (n=48), and group 2 (control group) included paired fellow eyes without amblyopia (n=32). The density of the superficial and deep vascular plexuses of the retina, choriocapillary layer, and avascular zone parameters (area, perimeter, and circumference) were evaluated using spectral optical coherence tomography (RS-3000 Advance 2, Nidek, Japan). Correlation analysis was performed using Pearsons linear correlation coefficient (r).
 RESULTS: No significant differences were found in the density of the superficial and deep retinal vessels, choriocapillary layer, and avascular zone parameters of the retina in eyes amblyopia of various origins compared with paired fellow eyes (p 0.05). No correlation was found between retinal perfusion data and functional and anatomical parameters of amblyopic eyes.
 CONCLUSION: No relationship was noted between the vascular parameters of the posterior pole of the eye and the maximally corrected visual acuity, which confirms the absence of changes in retinal perfusion in amblyopia and excludes its role in the pathogenesis.

Single-shot OCT and OCT angiography for slab-specific detection of diabetic retinopathy.

In this study, we present an optical coherence tomographic angiography (OCTA) prototype using a 500 kHz high-speed swept-source laser. This system can generate a 75-degree field of view with a 10.4 µm lateral resolution with a single acquisition. With this prototype we acquired detailed, wide-field, and plexus-specific images throughout the retina and choroid in eyes with diabetic retinopathy, detecting early retinal neovascularization and locating pathology within specific retinal slabs. Our device could also visualize choroidal flow and identify signs of key biomarkers in diabetic retinopathy.