Optimal transcorneal electrical stimulation parameters for preserving photoreceptors in a mouse model of retinitis pigmentosa.

JOURNAL/nrgr/04.03/01300535-202419110-00034/figure1/v/2024-03-08T184507Z/r/image-tiff Retinitis pigmentosa is a hereditary retinal disease that affects rod and cone photoreceptors, leading to progressive photoreceptor loss. Previous research supports the beneficial effect of electrical stimulation on photoreceptor survival. This study aims to identify the most effective electrical stimulation parameters and functional advantages of transcorneal electrical stimulation (tcES) in mice affected by inherited retinal degeneration. Additionally, the study seeked to analyze the electric field that reaches the retina in both eyes in mice and post-mortem humans. In this study, we recorded waveforms and voltages directed to the retina during transcorneal electrical stimulation in C57BL/6J mice using an intraocular needle probe with rectangular, sine, and ramp waveforms. To investigate the functional effects of electrical stimulation on photoreceptors, we used human retinal explant cultures and rhodopsin knockout (Rho-/-) mice, demonstrating progressive photoreceptor degeneration with age. Human retinal explants isolated from the donors' eyes were then subjected to electrical stimulation and cultured for 48 hours to simulate the neurodegenerative environment in vitro. Photoreceptor density was evaluated by rhodopsin immunolabeling. In vivo Rho-/- mice were subjected to two 5-day series of daily transcorneal electrical stimulation using rectangular and ramp waveforms. Retinal function and visual perception of mice were evaluated by electroretinography and optomotor response (OMR), respectively. Immunolabeling was used to assess the morphological and biochemical changes of the photoreceptor and bipolar cells in mouse retinas. Oscilloscope recordings indicated effective delivery of rectangular, sine, and ramp waveforms to the retina by transcorneal electrical stimulation, of which the ramp waveform required the lowest voltage. Evaluation of the total conductive resistance of the post-mortem human compared to the mouse eyes indicated higher cornea-to-retina resistance in human eyes. The temperature recordings during and after electrical stimulation indicated no significant temperature change in vivo and only a subtle temperature increase in vitro (~0.5-1.5°C). Electrical stimulation increased photoreceptor survival in human retinal explant cultures, particularly at the ramp waveform. Transcorneal electrical stimulation (rectangular + ramp) waveforms significantly improved the survival and function of S and M-cones and enhanced visual acuity based on the optomotor response results. Histology and immunolabeling demonstrated increased photoreceptor survival, improved outer nuclear layer thickness, and increased bipolar cell sprouting in Rho-/- mice. These results indicate that transcorneal electrical stimulation effectively delivers the electrical field to the retina, improves photoreceptor survival in both human and mouse retinas, and increases visual function in Rho-/- mice. Combined rectangular and ramp waveform stimulation can promote photoreceptor survival in a minimally invasive fashion.

The association between head injury and facial fracture treatment: an observational study of hospitalized bicyclists from a level 1 trauma centre.

PURPOSE: To compare the types of facial fractures and their treatment in bicyclists admitted to a level 1 trauma centre with major and minor-moderate head injury. METHODS: Retrospective analysis of data from bicycle-related injuries in the period 2005-2016 extracted from the Oslo University Hospital trauma registry. RESULTS: A total of 967 bicyclists with head injuries classified according to the Abbreviated Injury Scale (AIS) were included. The group suffering minor-moderate head injury (AIS Head 1-2) included 518 bicyclists, while 449 bicyclists had major head injury (AIS Head 3-6). The mean patient age was 40.2 years (range 3-91 years) and 701 patients (72%) were men. A total of 521 facial fractures were registered in 262 patients (on average 2 facial fractures per bicyclist). Bicyclists with major head injury exhibited increased odds for facial fractures compared to bicyclists with minor-moderate head injury (sex and age adjusted odds ratio (OR) 2.75, 95% confidence interval (CI) 2.03-3.72, p < 0.001. More specifically, there was increased odds for all midface fractures, but no difference for mandible fractures. There was also increased odds for orbital reconstruction in cyclist with major head injury compared to bicyclist with minor-moderate head injury (adjusted OR 3.34, 95% CI 1.30-8.60, p = 0.012). CONCLUSION: Bicyclists with more severe head injuries had increased odds for midface fractures and surgical correction of orbital fractures. During trauma triage, the head and the face should be considered as one unit.

Culture- and non-culture-based approaches reveal unique features of the ocular microbiome in dry eye patients.

PURPOSE: The purpose of this study was to investigate the ocular microbiome in individuals with dry eye disease and to identify features of their ocular microbiome of possible health and diagnostic significance. METHODS: Conjunctival samples were collected from both eyes in duplicate from 91 individuals (61 dry eye, 30 healthy) and used for both culture-dependent and culture-independent analyses. Samples were either analysed using next generation sequencing (V3-V4 16S rDNA) or inoculated on a wide range of agar types and grown under a broad range of conditions to maximize recovery. Isolates were identified by partial sequencing of the 16S rDNA and rpoB genes and tested for antibiotic susceptibility. We applied a L2-regularized logistic regression model on the next generation sequencing data to investigate any potential association between severe dry eye disease and the ocular microbiome. RESULTS: Culture-dependent analysis showed the highest number of colony forming units in healthy individuals. The majority of isolates recovered from the samples were Corynebacterium, Micrococcus sp., Staphylococcus epidermidis, and Cutibacterium acnes. Culture independent analysis revealed 24 phyla, of which Actinobacteria, Firmicutes and Proteobacteria were the most abundant. Over 405 genera were detected of which Corynebacterium was the most dominant, followed by Staphylococcus and Cutibacterium. The L2-regularized logistic regression model indicated that Blautia and Corynebacterium sp. may be associated with severe DED. CONCLUSIONS: Our study indicates that the ocular microbiome has characteristic features in severe DED patients. Certain Corynebacterium species and Blautia are of particular interest for future studies.

Ectropion. / Ektropion.

In ectropion, the eyelid margin - typically the lower eyelid - is turned outward. This condition is becoming increasingly common due to the ageing population. Ectropion is classified as either acquired or congenital, with the former being the most prevalent. Acquired ectropion is further divided into involutional, paralytic, mechanical and cicatricial subtypes. Involutional ectropion is the most common where there is no patient population bias. This clinical review provides an overview of ectropion.

Investigation of Roles of SLC38A1 in Proliferation and Differentiation of Mouse Tongue Epithelium and Expression in Human Oral Tongue Squamous Cell Carcinoma.

The aerobic glycolytic pathway, boosting lactate formation, and glutamine addiction are two hallmarks of cancer pathophysiology. Consistent with this, several cell membrane glutamine transporters, belonging to different solute carrier (SLC) families, have been shown to be upregulated in a cell-specific manner to furnish the cells with glutamine and glutamine-derived metabolic intermediates. Among them, the system A transporter Slc38a1 has a higher affinity for glutamine compared to other SLC transporters, and it undergoes highly multifaceted regulation at gene and protein levels. The current study aimed to investigate the functional role of Slc38a1 in the proliferation and maturation of the mouse tongue epithelium. Secondly, we aimed to examine the expression of SLC38A1 and its regulation in human tongue oral squamous cell carcinoma (OTSCC). Employing Slc38a1 wild-type and knockout mice, we showed that Slc38a1 was not directly linked to the regulation of the proliferation and differentiation of the mouse tongue epithelium. External transcriptomic datasets and Western blot analyses showed upregulation of SLC38A1 mRNA/protein in human OTSCC and oral cancer cell lines as compared to the corresponding controls. Further, an investigation of external datasets indicated that mechanisms other than the amplification of the SLC38A1 chromosomal locus or hypomethylation of the SLC38A1 promoter region might be important for the upregulation of SLC38A1 in OTSCC.

Chalazion Treatment: A Concise Review of Clinical Trials.

A chalazion is one of the most common eye conditions presenting as a mass lesion of the eyelids. It is seen in all age groups. Chalazion is a non-inflammatory process and develops due to retained secretion of the meibomian or Zeis glands. Treatment of choice differs among clinicians and may include application of warm compress onto eyelids, lid hygiene, using local antibiotic ointment with or without steroids, injecting steroid solution (triamcinolone acetonide) into the lesion and surgical removal of the lesion by incision and curettage. In addition, there are some other experimented methods such as injection of botulinum toxin A, tarsal trephination, removal of chalazion by application of CO2 laser or cryogenic action. However, there is currently no commonly agreed treatment of choice. In this review, we aimed to summarize findings from clinical trials and hopefully, identify a treatment of choice in chalazion.

Tear film proteome changes following Tobradex® therapy in anterior blepharitis.

PURPOSE: The management of blepharitis continues to challenge clinicians due to the poorly understood aetiology of the condition. We recently identified the family of intracellular plakin proteins as essential driving forces underlying anterior blepharitis. A large-scale protein analysis was used to study if a topical dexamethasone/tobramycin solution could be used to reverse the expression of plakin proteins. METHODS: Tear film samples from treatment naïve patients with anterior blepharitis (n = 15) were collected with Schirmer filtration paper. A subgroup of the patients (n = 10) received treatment with a dexamethasone/tobramycin 1 + 3 mg/mL ophthalmic suspension (Tobradex® ) for 3 weeks and collection of tear film samples was repeated. The samples were analysed with label-free quantification nano liquid chromatography-tandem mass spectrometry requiring quantification in at least 70% of the samples in each group. Proteins were considered differentially expressed if p < 0.05. RESULTS: Following Tobradex® intervention, 27 proteins were upregulated while 61 proteins were downregulated. Regulated proteins after Tobradex® treatment were involved in intermediate filament cytoskeleton organization including downregulation of the plakin proteins envoplakin, epiplakin and periplakin. Plectin, a protein of the plakin family, remained unchanged after Tobradex® therapy. Tobradex® treatment resulted in the regulation of proteins involved in translation including a cluster of downregulated ribosomal proteins. Tobradex® intervention was associated with the regulation of proteins involved in fructose metabolism and glycolytic processes including fructose-1.6-bisphosphatase 1, fructose-bisphosphate aldolases A and B, pyruvate kinase PKM and transketolase. Ig lambda chain V-I region, prominin-1, and protein Niban were upregulated after Tobradex® treatment. CONCLUSIONS: Tobradex treatment reversed the expression of plakin proteins in anterior blepharitis. Topical solutions which inhibit the expression of plakin proteins may have the potential to restore the ocular surface integrity in anterior blepharitis and should be explored further.

Meibomian Gland Dysfunction Is Associated with Low Levels of Immunoglobulin Chains and Cystatin-SN.

Meibomian gland dysfunction (MGD) is a highly prevalent condition and the most common cause of evaporative dry eye disease. Studying the proteome of MGD can result in important advances in the management of the condition. Here, we collected tear film samples from treatment naïve patients with MGD (n = 10) and age-matched controls (n = 11) with Schirmer filtration paper. The samples were analyzed with label-free quantification nano liquid chromatography-tandem mass spectrometry. The proteins were considered differentially expressed if p < 0.05. A total of 88 proteins were significantly regulated. The largest change was observed in cystatin-SN, which was downregulated in MGD and correlated negatively with tear meniscus height. The downregulation of cystatin-SN was confirmed with targeted mass spectrometry by single reaction monitoring (SRM). Eighteen immunoglobulin components involved in B cell activation, phagocytosis, and complement activation were downregulated in MGD including Ig alpha-1 chain C region, immunoglobulin J chain, immunoglobulin heavy variable 3-15, and Ig mu chain C region. The changes in cystatin-SN and immunoglobulin chains are likely to result from the inflammatory changes related to tear film evaporation, and future studies may assess their association with the meibum quality.

RNA Profiles of Tear Fluid Extracellular Vesicles in Patients with Dry Eye-Related Symptoms.

Currently, diagnosing and stratifying dry eye disease (DED) require multiple tests, motivating interest in a single definitive test. The purpose of this study was to investigate the potential for using tear fluid extracellular vesicle (EV)-RNA in DED diagnostics. With a role in intercellular communication, nanosized EVs facilitate the protected transport of diverse bioactive molecules in biofluids, including tears. Schirmer strips were used to collect tears from 10 patients presenting with dry eye-related symptoms at the Norwegian Dry Eye Clinic. The samples comprised two groups, five from patients with a tear film break-up time (TBUT) of 2 s and five from patients with a TBUT of 10 s. Tear fluid EV-RNA was isolated using a Qiagen exoRNeasy Midi Kit, and the RNA was characterized using Affymetrix ClariomTM D microarrays. The mean signal values of the two groups were compared using a one-way ANOVA. A total of 26,639 different RNA transcripts were identified, comprising both mRNA and ncRNA subtypes. Approximately 6% of transcripts showed statistically significant differential abundance between the two groups. The mRNA sodium channel modifier 1 (SCNM1) was detected at a level 3.8 times lower, and the immature microRNA-130b was detected at a level 1.5 times higher in the group with TBUT 2 s compared to the group with TBUT 10 s. This study demonstrates the potential for using tear fluid EV-RNA in DED diagnostics.

Non-Coding RNA in Salivary Extracellular Vesicles: A New Frontier in Sjögren's Syndrome Diagnostics?

Sjögren's syndrome is an autoimmune rheumatic disease characterized by inflammation of the salivary and lacrimal glands, often manifesting as dry mouth and dry eyes. To simplify diagnostics of primary Sjögren's syndrome (pSS), a non-invasive marker is needed. The aim of the study was to compare the RNA content of salivary extracellular vesicles (EVs) between patients with pSS and healthy controls using microarray technology. Stimulated whole saliva was collected from 11 pSS patients and 11 age-matched controls. EV-RNA was isolated from the saliva samples using a Qiagen exoRNeasy Midi Kit and analyzed using Affymetrix Clariom D™ microarrays. A one-way ANOVA test was used to compare the mean signal values of each transcript between the two groups. A total of 9307 transcripts, coding and non-coding RNA, were detected in all samples. Of these transcripts, 1475 showed statistically significant differential abundance between the pSS and the control groups, generating two distinct EV-RNA patterns. In particular, tRNAs were downregulated in pSS patients, with the transcript tRNA-Ile-AAT-2-1 showing a 2-fold difference, and a promise as a potential biomarker candidate. This study therein demonstrates the potential for using salivary EV-RNA in pSS diagnostics.

Cross-sectional Study Exploring Vision-related Quality of Life in Dry Eye Disease in a Norwegian Optometric Practice.

SIGNIFICANCE: Dry eye disease causes ocular pain, blurred vision, reduced visual quality of life, and reduced workplace performance. This disease is underreported and underdiagnosed despite being highly prevalent in optometric care. PURPOSE: This study aimed to explore the vision-related quality of life of patients with dry eye disease and the potential benefits of screening for dry eye disease in Norwegian optometric practice. METHODS: This study adopted an observational, prospective, cross-sectional design. All patients between 18 and 70 years of age who were examined between June 8 and July 5, 2018, at Erøy Optikk, Kristiansand, Norway, were invited to participate. Dry eye disease was assessed according to Tear Film & Ocular Surface Society International Dry Eye Workshop II report recommendations. Vision-related quality of life was assessed with the National Eye Institute 25-item Visual Function Questionnaire. RESULTS: Forty-nine patients participated in the study; 29 (59%) were female, and 29 (59%) had dry eye disease. The patients with dry eye disease reported significantly more ocular pain and (vision-specific) role difficulties than the patients without dry eye disease. After adjusting for age, sex, and habitual visual acuity, dry eye disease was found to be an independent predictor of both ocular pain ( r2 = 0.328, P = .001) and (vision-specific) role difficulties ( r2 = 0.240, P = .02). Both habitual visual acuity and dry eye disease were predictors of reduced general vision, a reduced score for near activity and reduced (vision-specific) mental health. CONCLUSIONS: Dry eye disease was an independent predictor of ocular pain (vision-specific), role difficulties, and reduced general vision, near vision, and (vision-specific) mental health. Optometrists should consider dry eye disease as a cause of reduced vision and quality of vision. Furthermore, we propose that screening for dry eye disease in Norwegian optometric practice can promote better vision and health among patients.

Surgical Procedures in the Treatment of Dry Eye Disease.

Dry eye disease (DED) is a multifactorial disease affecting 5% to 50% in different populations. The most severe cases of DED are often caused by aqueous deficient dry eye disease (ADDE) due to lacrimal gland (LG) hypofunction. Many patients with severe ADDE do not experience adequate symptom relief from topical treatment, severely reducing their quality of life. The focus of this review is to describe the surgical interventions presently being used or investigated when topical treatment with eye drops is insufficient. The conventional surgical approach is to proceed to punctal occlusion or partial or total tarsorrhaphy. However, novel surgical procedures have been reported to have higher efficacy and patient satisfaction than conventional treatments. These procedures include amniotic membrane transplantation, transposition or transplantation of the salivary glands, and cell-based injections into the LG, each with strengths and weaknesses. Further development of these treatment modalities might prove pivotal in treating dry eye patients in the future.

Electrical stimulation alters DNA methylation and promotes neurite outgrowth.

Electrical stimulation (ES) influences neural regeneration and functionality. We here investigate whether ES regulates DNA demethylation, a critical epigenetic event known to influence nerve regeneration. Retinal ganglion cells (RGCs) have long served as a standard model for central nervous system neurons, whose growth and disease development are reportedly affected by DNA methylation. The current study focuses on the ability of ES to rescue RGCs and preserve vision by modulating DNA demethylation. To evaluate DNA demethylation pattern during development, RGCs from mice at different stages of development, were analyzed using qPCR for ten-eleven translocation (TETs) and immunostained for 5 hydroxymethylcytosine (5hmc) and 5 methylcytosine (5mc). To understand the effect of ES on neurite outgrowth and DNA demethylation, cells were subjected to ES at 75 µAmp biphasic ramp for 20 min and cultured for 5 days. ES increased TETs mediated neurite outgrowth, DNA demethylation, TET1 and growth associated protein 43 levels significantly. Immunostaining of PC12 cells following ES for histone 3 lysine 9 trimethylation showed cells attained an antiheterochromatin configuration. Cultured mouse and human retinal explants stained with ß-III tubulin exhibited increased neurite growth following ES. Finally, mice subjected to optic nerve crush injury followed by ES exhibited improved RGCs function and phenotype as validated using electroretinogram and immunohistochemistry. Our results point to a possible therapeutic regulation of DNA demethylation by ES in neurons.

Ocular Surface Homeostasis After Scleral Lens Usage.

OBJECTIVES: The aim of this prospective study is to examine the effects of 5 hours of well-fitted, mini-scleral contact lens (mini-SL) wear on the tear film cytokine expression in healthy eyes. METHODS: Twenty-three healthy participants were included in the study. One eye of each participant was selected at random, and a mini-SL measuring 16.5 mm in diameter was fitted by an experienced contact lens specialist. The contact lens remained in place for 5 hours. Precorneal tear fluid was collected using capillary tubes at three different time points: baseline before SL insertion (T0), after 5 hours of SL wear (T1), and 3 hours after SL removal (T2). The concentration of 40 inflammatory cytokines at the three different time points was determined using multiplex bead assay. RESULTS: Mini-scleral lens wear did not result in significant changes in the cytokine-to-protein ratio after 5 hours of wear on a healthy eye. CONCLUSIONS: Although a well-fitted mini-SL reduces the rate at which the precorneal tear film is refreshed, 5 hours of lens wear did not appear to significantly affect the tears cytokine-to-protein ratio, suggesting that scleral lenses have minimal impact on corneal cytokine expression.

Suture materials. / Suturmaterialer.

Suture materials are of crucial importance for most surgical procedures, and knowledge about these is useful for all doctors. This clinical review article gives an introduction to the most common suture materials and their properties. Lastly, recent trends in suture technology are presented.

Anterior blepharitis is associated with elevated plectin levels consistent with a pronounced intracellular response.

PURPOSE: Anterior blepharitis is a frequent ocular condition which may result in severe ocular surface disease. In this study, advanced proteome analysis was performed to elucidate biological mechanisms underlying anterior blepharitis. METHODS: All patients underwent full ophthalmological examination including Ocular Surface Disease Index score (OSDI). Measurement of non-invasive break-up time (NBUT), Oxford score, and meibography were performed. Tear film samples from treatment naïve patients with anterior blepharitis (n = 15) and age-matched controls (n = 11) were collected with Schirmer filtration paper. The samples were analyzed with label-free quantification nano liquid chromatography - tandem mass spectrometry (LFQ nLC-MS/MS). Significantly regulated proteins were identified with a permutation-based calculation with a false discovery rate at 0.05. RESULTS: Among the 927 proteins detected, a total of 162 proteins were significantly changed. Regulated proteins were involved in cytoplasmic translation, positive regulation of B cell activation, complement activation and phagocytosis. High levels of plakin proteins, a group of proteins involved in cytoskeleton organization, were observed in anterior blepharitis, including plectin, desmoplakin, envoplakin, epiplakin, periplakin, and vimentin. The upregulation of plectin was confirmed with single reaction monitoring. Patients with anterior blepharitis had lower levels of immunoglobulin chains, VEGF coregulated chemokine 1 (CXCL17), and platelet-derived growth factor C. CONCLUSIONS: Anterior blepharitis was associated with a high level of plectin indicating a pronounced intracellular response with cytoskeletal reorganization. Our data suggest a lack of immunoglobulin chains and CXCL17 in anterior blepharitis with potential alterations in the ocular surface immune response.

Ex Vivo Pig Eye Model for Studying Diffusion of Acylcarnitines with Different Physicochemical Properties.

Purpose: To explore the diffusion capacities between the anterior and vitreous chambers in a novel ex vivo pig eye model using a mix of stable isotope-labeled acylcarnitines representing metabolites with different physical and chemical properties, and analysis using mass spectrometry (MS). Methods: Enucleated pig eyes were injected in the anterior or vitreous chamber of the eye with a stable isotope-labeled acylcarnitine mix (free carnitine, C2, C3, C4, C8, C12, and C16-having an increasing size and hydrophobicity in that order). Samples were collected from each chamber at 3, 6, and 24 h postincubation for analysis using MS. Results: After injection into the anterior chamber, the concentration of all acylcarnitines increased in the vitreous chamber over the observation period. After injection in the vitreous chamber, the acylcarnitines diffused to the anterior chamber with the highest concentration observed at 3 h postinjection, followed by a decrease in concentration possibly due to an elimination from the anterior chamber despite continued diffusion from the vitreous chamber. C16, the most hydrophobic and longest chain molecule, showed slower diffusion in both experimental settings. Conclusion: We hereby show a distinct diffusion pattern of molecules with different molecular size and hydrophobicity within and between the anterior and vitreous chamber. This model can be useful for optimizing choices and design of therapeutic molecules with higher retaining or depot properties into the two chambers of the eye for future intravitreal, intracameral, and topical treatment purposes.

Comparison of Novel Wide-Field In Vivo Corneal Confocal Microscopy With Skin Biopsy for Assessing Peripheral Neuropathy in Type 2 Diabetes.

Diabetic peripheral neuropathy (DPN) is a serious complication of diabetes, where skin biopsy assessing intraepidermal nerve fiber density (IENFD) plays an important diagnostic role. In vivo confocal microscopy (IVCM) of the corneal subbasal nerve plexus has been proposed as a noninvasive diagnostic modality for DPN. Direct comparisons of skin biopsy and IVCM in controlled cohorts are lacking, as IVCM relies on subjective selection of images depicting only 0.2% of the nerve plexus. We compared these diagnostic modalities in a fixed-age cohort of 41 participants with type 2 diabetes and 36 healthy participants using machine algorithms to create wide-field image mosaics and quantify nerves in an area 37 times the size of prior studies to avoid human bias. In the same participants, and at the same time point, no correlation between IENFD and corneal nerve density was found. Corneal nerve density did not correlate with clinical measures of DPN, including neuropathy symptom and disability scores, nerve conduction studies, or quantitative sensory tests. Our findings indicate that corneal and intraepidermal nerves likely mirror different aspects of nerve degeneration, where only intraepidermal nerves appear to reflect the clinical status of DPN, suggesting that scrutiny is warranted concerning methodologies of studies using corneal nerves to assess DPN. ARTICLE HIGHLIGHTS: Comparison of intraepidermal nerve fiber density with automated wide-field corneal nerve fiber density in participants with type 2 diabetes revealed no correlation between these parameters. Intraepidermal and corneal nerve fibers both detected neurodegeneration in type 2 diabetes, but only intraepidermal nerve fibers were associated with clinical measures of diabetic peripheral neuropathy. A lack of association of corneal nerves with peripheral neuropathy measures suggests that corneal nerve fibers may be a poor biomarker for diabetic peripheral neuropathy.