Loss Of Transparency Research Articles

Aggregation inhibitory effect of vitamin C on cataract-associated P23T γD-crystallin.

Cataract is a progressive loss of eye lens transparency, as a result of age-related chemical modifications or due to congenital mutations in crystallins. A vital antioxidant in the aqueous humor, the vitamin C, has been suggested to hold potential for the prophylaxis of age-related cataract. However, the effect of vitamin C on congenital cataract has not yet been investigated. Here, we explored the aggregation inhibitory effect of vitamin C on the P23T human γD-crystallin mutant, associated with congenital cataract. The effect of vitamin C on the aggregation propensity of P23T human γD-crystallin was investigated by solution NMR, atomic force microscopy (AFM), and other biophysical techniques. We found that vitamin C is able to prevent and reverse P23T human γD-crystallin aggregation in a dose-dependent manner. In particular, NMR data suggest that the inhibitory effect of vitamin C on P23T human γD-crystallin phase-separation is probably mediated by interacting with aggregation prone regions. AFM images of P23T human γD-crystallin under native aggregating conditions revealed the appearance of amorphous aggregates, that disassemble into monomers in the presence of vitamin C. The current study highlights and confirms the possibility that vitamin C is able to dissolve crystallin aggregates, potentially slowing the onset or reversing cataract.

DOP077 EndoUC: an AI-assisted endoscopic Ulcerative Colitis activity grading application for deployment in clinical trials

Abstract Background Manual scoring of ulcerative colitis (UC) disease activity from endoscopy videos using the Modified Mayo Score (mMS) by experts is known to have high inter-rater and intra-rater variability.1 In clinical trials, central reviewers review endoscopy videos and provide a single score for the entire video leading to a loss of transparency with no evidence of scoring rationale or segmental involvement. We developed an AI-assisted severity scoring application for clinical trials to address this challenge by intelligently highlighting video segments showing pathological information and providing a continuous scoring approach to severity grading. Methods Unlike previous approaches that rely heavily on large-scale, expensive, and restrictive frame-level expert labels, we developed our models on video-level grading available in typical clinical trial settings. We used data from the brazikumab clinical trial [NCT03616821], comprising 423 videos from 249 patients scored on the mMS scale. Our preprocessing module removes uninformative, low-quality frames and applies detection, tracking and alignment algorithms to identify regions of interest across frames. Our EndoUC model has 3 components: a pathology-enriched frame identification module (PEFIM), an aggregator, and a classifier.The PEFIM module identifies regions that characterise signs of UC, such as ulcers or erosions. The aggregator and classifier modules learn to combine the information at the video level. We focus on the clinical utility of the EndoUC model in two ways: (i) having task-specific classifiers focusing on clinical decision boundaries of UC and (ii) enhancing scoring granularity of UC severity prediction using ordinal regression. Results We developed an application to enable experts to review lengthy endoscopy footage in clinical trials efficiently. The app allows seamless navigation to key regions identified by the EndoUC and transparently reveals the basis of the AI model’s assessments. We conducted 5-fold cross-validation on the clinical trial data and evaluated the model on a held-out test set with 87 videos. The remission (mMS 0, 1 vs 2, 3) model performs with an AUC-ROC of 0.85, F1 of 0.87, normal/inactive and severe models with AUC-ROC of 0.81and 0.83 respectively. The continuous grading model has an MSE of 0.42 and MAE of 0.40. Conclusion We developed an AI-assisted reading tool for UC endoscopic severity assessment to help accelerate clinical trails through rapid evaluation of patient eligibility, detection of treatment response grounded by key region evidence, and potential for continuous grading of endoscopic changes.

Knockout of TMEM206 in mice associated with a loss of corneal transparency.

To investigate the role of transmembrane protein 206 (TMEM206) in corneal edema in mice by knockout the TMEM206 gene using CRISPR/Cas9 editing technology. TMEM206-knockout mice were generated using the CRISPR-Cas9 system. Variations in ophthalmic pathology were observed using slit lamp microscope and optical coherence tomography (OCT), intraocular pressure (IOP) was measured using a TonoLab Rebound Tonometer, and the ultrastructure of the corneal was observed using a transmission electron microscope. Corneal opacity was observed in 4/18 homozygous TMEM206-/- mice whereas a similar change was not observed in heterozygous TMEM206+/- mice and wild-type littermates. OCT examination showed that the mean central cornea thickness was 125±5.4 µm in 4 homozygous TMEM206-/- mice developed corneal edema and 115±1.2 µm in wild-type mice (t=3.468, P<0.05) at 43wk. The mean IOP was 12.08±0.07 mm Hg in four right eyes with corneal edema and 12.03±0.03 mm Hg in three normal left eyes (P>0.05). Transmission electron microscopy revealed a disruption in the organization of the collagen fibrils in the central part of the cornea in homozygous TMEM206-/- mice. TMEM206 is associated with corneal edema which caused organizational disruption of collagen fibrils in corneas of mice.

Effect of Chlorine Inclusion in Wide Band Gap FAPbBr3 Perovskites

AbstractWide bandgap perovskites have recently gained attention owing to their physical properties, versatility, and potential in various optoelectronic devices including LEDs, detectors, and building‐integrated photovoltaics (BIPV). However, BIPV materials must meet conflicting requirements, necessitating high performance, high transparency in the visible spectrum and color neutrality. This study investigates the controlled addition of chlorine in FAPb(Br1‐xClx)3 perovskites to achieve band gaps exceeding 2.4 eV. Increasing chlorine content from xCl = 0.00 to xCl = 0.25 widens the band gap from 2.37 to 2.52 eV, effectively improving the visible light transparency. Advanced characterization techniques including X‐ray diffraction, synchrotron radiation photoelectron spectroscopy, photoluminescence imaging, and fast transient absorption spectroscopy, complemented by density functional theory, reveal insights into absorption properties, electronic structure, and ultrafast recombination dynamics as a function of the thin film chemical composition. Furthermore, this study evaluates energetic disorder, carrier recombination rates, and non‐radiative losses for different compositions by extracting quantitative parameters such as Urbach energy and quasi‐Fermi level splitting, offering novel insights and guidelines for the design and optimization of emerging photovoltaic (PV) materials. Optimal PV performance metrics are achieved with a wide bandgap bromine perovskite containing 14% chlorine, striking a balance between morphology, transparency, and voltage losses.

Complacency in the quantification and reporting of climate impacts as carbon dioxide equivalent emissions

PurposeThe choice of characterization model has the potential to profoundly influence LCA results and conclusions. It is therefore a requirement of ISO 14044:2006 that the selection of characterization model shall be both justified and consistent with goal and scope. The purpose of this article was to examine current practices regarding the characterization of GHG emissions and reporting as CO2 equivalent emissions.MethodsA survey of practice was conducted across articles recently published in the International Journal of Life Cycle Assessment. Each article was examined using seven predetermined questions covering reporting of CO2 equivalent emissions and justification of climate metric used, interpretation of results in relation to climate measures or goals, and the implications of choosing an alternative climate metric.Results and discussionOf the sample of 85 articles, more than half reported GHG emissions as CO2 equivalent emissions. Of these, 81% unambiguously reported the climate metric used. Most often, there was no justification for the choice of a characterization model. Where a justification was given, the most common reason was alignment with the requirements of a program or PCR document. In some cases, the choice of characterization model was determined by the choice of impact assessment method (e.g., CML, ReCiPe). In other cases, the choice of characterization model was based on the desire to compare results to other studies. It is noted that none of the abovementioned reasons is scientific justification related to a stated climate objective. Not surprisingly, most studies made no attempt to interpret results reported as CO2 equivalent emissions in relation to climate measures or goals, and most did not discuss the potential implications of alternative climate metrics. For almost half of the articles, the choice of climate metric was assessed as potentially having major implications for decision-making or comparison to alternative systems.ConclusionsBased on this survey, it is evident that key aspects of ISO 14044:2006 are routinely not being followed. When GHG emissions are aggregated into a single impact category indicator result, there is a loss of transparency about climate impacts over time and the potential to unknowingly trade short-term climate benefits against the exacerbation of the difficulties of achieving long-term climate stabilization. As such, whenever GHG emissions are reported as CO2 equivalent emissions, it is imperative that the choice of characterization model is unambiguously reported and justified, that results are interpreted in relation to environmental outcomes, and that the potential implications of selecting alternative models are discussed.Graphical

Characterization of the Retinal Phenotype Using Multimodal Imaging in Novel Compound Heterozygote Variants of CYP2U1

To report the retinal phenotype in 2 patients simulating type 2 macular telangiectasis with new variants in CYP2U1 implicated in hereditary spastic paraplegia type 56 (HSP 56). Cross sectional case series study. Five members of a non-consanguineous family (parents and 3 male children) were investigated. All family members underwent a full ophthalmic evaluation and multimodal retinal imaging. Two family members demonstrating retinal anomalies underwent additional OCT angiography, dual wavelength autofluorescence and fluorescence lifetime imaging ophthalmoscopy, kinetic perimetry, fundus-correlated microperimetry, electroretinography, and electro-oculography. Whole-exome sequencing was performed in all 5 family members. To characterize the retinal phenotype in affected patients with variants in CYP2U1, using multimodal imaging: dual-wavelength autofluorescence, fluorescence lifetime, OCT angiography. The 2 siblings with compound heterozygous novel variants c.452C>T; p.(Pro151Leu), c.943C>T; p.(Gln315Ter) in CYP2U1 demonstrated parafoveal loss of retinal transparency and hyperreflectivity to blue light, redistribution of macular pigment to the parafoveal edge, photoreceptor loss, and fluorescence lifetime imaging ophthalmoscopy anomalies: a pattern compatible with that seen in macular telangiectasia type 2 (MacTel). One had manifest neurological abnormalities since early childhood; the second had no neurological abnormalities. Each parent and the third sibling were heterozygous for 1 variant and were neurologically and ophthalmically normal. These CYP2U1 variants are associated with a retinal phenotype very similar to that otherwise specific for MacTel, suggestive of possible links in the etiology and pathogenesis of these diseases. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

A facile route to fabricate transparent and mechanically robust glass-fabric reinforced composites via refractive index matching and tow-spreading technique

There are challenges to fabricate GFRPs with high optical clarity and mechanical performance due to the inevitable chromatic dispersion and yarn crimp in the fabric. Herein, a facile route to fabricate transparent glass-fabric reinforced composites is reported using refractive index matching and tow-spreading technique. By introducing different amount of BMA, the epoxy matrix could match the refractive index of glass fibers at different wavelength. The fabricated composites exhibit intriguing pale blue/blue, dark blue/ purple, purple-pink/pink chromatic dispersion, respectively. Among them, the 0.2 mm-thick GFRP with 4 % BMA (fiber volume fraction ≈ 50.4 %) exhibits the highest total transmittance (89.5 %) and lowest haze (3.4 %). Compared with commercial standard-tow fabric, composites with spread-tow fabrics exhibits less chromatic dispersion and transparency loss. Moreover, simultaneously reinforcing and toughening effect could be observed in the composites with BMA modified matrix. The optimized composites possess tensile strength of 289 MPa and flexural strength of 416 MPa.

Fuchs endothelial corneal dystrophy: aspects of pathogenesis

Fuchs endothelial corneal dystrophy (FECD) – multigenic bilateral disorder, characterized by dysfunction of corneal endothelium cells (CECs) that eventually results in loss of transparency. Purpose: To evaluate the pathogenesis of FECD with histological and immunohistochemical methods, immunofluorescence, scanning electron microscopy (SEM). Methods: Endothelium–Descemet membrane (EDM) complexes, corneal buttons were obtained from 76 patients (85 eyes) with FECD during keratoplasty and divided into 1A, 2A, 3A groups, 15 EDMs (donor tisuue) – 1B, 2B, 3B groups (control). Morphological (hematoxylin/eosin staining) and immunohistochemical (primary antibodies to cytokeratin AE1/AE3 and vimentin) studies (1A, 1B groups), phase-contrast microscopy and immunofluorescence analysis of tight junction protein ZO-1 (2A, 2B groups), SEM (3A, 3B groups) were performed. Results: FECD is characterized by decline of CECs, cell and nuclear enlargement. Nuclear-cytoplasmic ratio of CECs is relative to control. CECs expression ZO-1 is decreased in the area of guttae ingrowth. Coexpression of cytokeratin AE1/AE3 and vimentin is found. Morphological and immunohistochemical studies show DM’ thickening, stromal and epithelial edema and local fibrosis, vimentin (stromal cells) and cytokeratin AE1/AE3 (epithelium) expression in FECD. Conclusion: Pathogenesis of FECD include CECs’ epithelial-mesenchymal transition, followed by guttae formation – the excrescences, which destroy cytosketon and lead to progressive loss of CECs. Changes in permeability of endothelium cause edema and fibrosis of stroma and epithelial layer.

Trimebutine prevents corneal inflammation in a rat alkali burn model

Alkaline burns to the cornea lead to loss of corneal transparency, which is essential for normal vision. We used a rat corneal alkaline burn model to investigate the effect of ophthalmic trimebutine solution on healing wounds caused by alkaline burns. Trimebutine, an inhibitor of the high-mobility group box 1-receptor for advanced glycation end products, when topically applied to the burned cornea, suppressed macrophage infiltration in the early phase and neutrophil infiltration in the late phase at the wound site. It also inhibited neovascularization and myofibroblast development in the late phase. Furthermore, trimebutine effectively inhibited interleukin-1β expression in the injured cornea. It reduced scar formation by decreasing the expression of type III collagen. These findings suggest that trimebutine may represent a novel therapeutic strategy for corneal wounds, not only through its anti-inflammatory effects but also by preventing neovascularization.

Enhancing the IFM framework based on a meta-analysis of other design methods

AbstractThe use of design methods across multiple design phases of the product development process often leads to inconsistency, the loss of transparency, and the rejection of design methods by practitioners. The authors of this work intend to develop a central modelling approach that supports consistency, based on the integrated function modelling (IFM) framework. Therefore, various design methods from the literature were examined for their techniques and content to identify indicators for supporting consistency. The results led to an enhancement of the IFM framework.

Optically transparent meta-window for satellite signal reception

Glass window, as a widely used functional unit in architecture and transportation, is a visual bridge connecting the indoor and outdoor world, and also a wireless communication window that is easily overlooked. In order to explore additional possibilities of glass window in the field of wireless communication, we propose to use meta-windows combining traditional window glass with metasurface to manipulate electromagnetic waves in microwave frequency band while ensuring its good optical transparency. Here, the meta-window is constructed by rotated meta-atoms made of fine copper wires printed on glasses to minimize the loss of optical transparency. As a proof of concept, we design and fabricate an optically transparent focusing meta-window for receiving satellite signals. In the experiment of television reception from the ChinaSat 9 satellite, stable high-definition video reception has been verified. The meta-windows endow traditional glass windows with new capabilities in electromagnetic modulations, which may be applied in 5G/6G communications, satellite ground integrations, and smart cities.

UV light-mediated corneal crosslinking as (lymph)angioregressive pretreatment to promote graft survival after subsequent high-risk corneal transplantation (CrossCornealVision): protocol for a multicenter, randomized controlled trial

BackgroundGood vision highly depends on the transparency of the cornea, which is the “windscreen” of the eye. In fact, corneal blindness due to transparency loss is the second most common cause of blindness worldwide, and corneal transplantation is the main cure. Importantly, the cornea is normally avascular but can secondarily be invaded by pathological (blood and lymphatic) vessels due to severe inflammation, and the survival prognosis of a corneal graft mainly depends on the preoperative vascular condition of the recipient’s cornea. Whereas transplants placed into avascular recipient beds enjoy long-term survival rates of > 90%, survival rates significantly decrease in pathologically pre-vascularized, so-called high-risk recipients, which account for around 10% of all performed transplants in Germany and > 75% in lower and middle-income countries worldwide.MethodsThis parallel-grouped, open-randomized, multicenter, prospective controlled exploratory investigator-initiated trial (IIT) intends to improve graft survival by preconditioning pathologically vascularized recipient corneas by (lymph)angioregressive treatment before high-risk corneal transplantation. For this purpose, corneal crosslinking (CXL) will be used, which has been shown to potently regress corneal blood and lymphatic vessels. Prior to transplantation, patients will be randomized into 2 groups: (1) CXL (intervention) or (2) no pretreatment (control). CXL will be repeated once if insufficient reduction of corneal neovascularization should be observed. All patients (both groups) will then undergo corneal transplantation. In the intervention group, remaining blood vessels will be additionally regressed using fine needle diathermy (on the day of transplantation). Afterwards, the incidence of graft rejection episodes will be evaluated for 24 months (primary endpoint). Overall graft survival, as well as regression of corneal vessels and/or recurrence, among other factors, will be analyzed (secondary endpoints).DiscussionBased on preclinical and early pilot clinical evidence, we want to test the novel concept of temporary (lymph)angioregressive pretreatment of high-risk eyes by CXL to promote subsequent corneal graft survival. So far, there is no evidence-based approach to reliably improve graft survival in the high-risk corneal transplantation setting available in clinical routine. If successful, this approach will be the first to promote graft survival in high-risk transplants. It will significantly improve vision and quality of life in patients suffering from corneal blindness.Trial registrationClinicalTrials.gov NCT05870566. Registered on 22 May 2023.

Corneal wound healing-Pharmacological treatment

Physiological wound healing of the cornea is acomplex process and involves numerous multifactorial tissue processes. Aproper wound healing, especially without the formation of light-scattering scars, is essential to preserve the integrity and function of the cornea. Misdirected wound healing is of vast clinical relevance as it can lead to corneal fibrosis and the loss of optical transparency with subsequent reduction of visual acuity, up to blindness. In addition to the understanding of the pathophysiological mechanisms, the knowledge of therapeutic concepts and options for treating corneal wound healing disorders and fibrosis is essential to counteract apermanent damage of the cornea as early as possible. Nowadays, various pharmacological and surgical options are available for treatment. The decision, appropriate selection and indication for the optimal treatment depend primarily on the genesis and clinical appearance of the corneal wound, fibrosis or scar. The treatment of wound healing disorders ranges from the use of topical therapy and supportive measures up to tissue replacement procedures. As long as the mechanical stability of the cornea is intact and wound healing processes are still ongoing, apharmacological modulation is reasonable, which is discussed in this article.

Hydrophobic and Transparent Tantalum Pentoxide-Based Coatings for Photovoltaic (PV) Solar Panels

Photovoltaic (PV) solar panels suffer from efficiency losses due to the accumulation of dust on their surface during operation, as well as the loss of transparency in the top glass. The efficiency can be increased when hydrophobic films are deposited on the top glass of the solar cells. The top glass of solar cells must have three characteristics: high transmittance in the 380–750 nm range, a band gap greater than 3.2 eV and a refractive index higher than 1.23. So, the films require the same characteristics. This work presents an increase in the contact angle (related to an increase in the hydrophobic character) when Ta2O5 is partially substituted with ZnO. The studied films, physically deposited on glass by e-gun technology, present a non-crystalline state in the form of the X-ray patterns shown. The films have a transmission of 75%–80% in the visible range. The morphology and roughness of the coatings were evaluated by atomic force microscopy. All films show the values of the Millipore water contact angle higher than 91 degrees, leading to the acquisition of hydrophobic properties on the surface. In comparison, the substrate is hydrophilic, with an average contact angle of 53.81 ± 2.16. The hydrophobic properties and self-cleaning ability make the films recommendable for application. The band gap of the coatings was calculated with the Tauc method, and they have values of 4.5–4.6 eV.

Monitoring the Electrochemical Failure of Indium Tin Oxide Electrodes via Operando Ellipsometry Complemented by Electron Microscopy and Spectroscopy.

Transparent conductive oxides such as indium tin oxide (ITO) are standards for thin film electrodes, providing a synergy of high optical transparency and electrical conductivity. In an electrolytic environment, the determination of an inert electrochemical potential window is crucial to maintain a stable material performance during device operation. We introduce operando ellipsometry, combining cyclic voltammetry (CV) with spectroscopic ellipsometry, as a versatile tool to monitor the evolution of both complete optical (i.e., complex refractive index) and electrical properties under wet electrochemical operational conditions. In particular, we trace the degradation of ITO electrodes caused by electrochemical reduction in a pH-neutral, water-based electrolyte environment during electrochemical cycling. With the onset of hydrogen evolution at negative bias voltages, indium and tin are irreversibly reduced to the metallic state, causing an advancing darkening, i.e., a gradual loss of transparency, with every CV cycle, while the conductivity is mostly conserved over multiple CV cycles. Post-operando analysis reveals the reductive (loss of oxygen) formation of metallic nanodroplets on the surface. The reductive disruption of the ITO electrode happens at the solid-liquid interface and proceeds gradually from the surface to the bottom of the layer, which is evidenced by cross-sectional transmission electron microscopy imaging and complemented by energy-dispersive X-ray spectroscopy mapping. As long as a continuous part of the ITO layer remains at the bottom, the conductivity is largely retained, allowing repeated CV cycling. We consider operando ellipsometry a sensitive and nondestructive tool to monitor early stage material and property changes, either by tracing failure points, controlling intentional processes, or for sensing purposes, making it suitable for various research fields involving solid-liquid interfaces and electrochemical activity.

Research progress on ocular complications caused by type 2 diabetes mellitus and the function of tears and blepharons.

The purpose of this study was to explore the related research progress of ocular complications (OCs) caused by type 2 diabetes mellitus (T2DM), tear and tarsal function, and the application of deep learning (DL) in the diagnosis of diabetes and OCs caused by it, to provide reference for the prevention and control of OCs in T2DM patients. This study reviewed the pathogenesis and treatment of diabetes retinopathy, keratopathy, dry eye disease, glaucoma, and cataract, analyzed the relationship between OCs and tear function and tarsal function, and discussed the application value of DL in the diagnosis of diabetes and OCs. Diabetes retinopathy is related to hyperglycemia, angiogenic factors, oxidative stress, hypertension, hyperlipidemia, and other factors. The increase in water content in the corneal stroma leads to corneal relaxation, loss of transparency, and elasticity, and can lead to the occurrence of corneal lesions. Dry eye syndrome is related to abnormal stability of the tear film and imbalance in neural and immune regulation. Elevated intraocular pressure, inflammatory reactions, atrophy of the optic nerve head, and damage to optic nerve fibers are the causes of glaucoma. Cataract is a common eye disease in the elderly, which is a visual disorder caused by lens opacity. Oxidative stress is an important factor in the occurrence of cataracts. In clinical practice, blood sugar control, laser therapy, and drug therapy are used to control the above eye complications. The function of tear and tarsal plate will be affected by eye diseases. Retinopathy and dry eye disease caused by diabetes will cause dysfunction of tear and tarsal plate, which will affect the eye function of patients. Furthermore, DL can automatically diagnose and classify eye diseases, automatically analyze fundus images, and accurately diagnose diabetes retinopathy, macular degeneration, and other diseases by analyzing and processing eye images and data. The treatment of T2DM is difficult and prone to OCs, which seriously threatens the normal life of patients. The occurrence of OCs is closely related to abnormal tear and tarsal function. Based on DL, clinical diagnosis and treatment of diabetes and its OCs can be carried out, which has positive application value.

Exploring the Role of ROCK Inhibition in Corneal Edema Through Crosstalk Between Epithelial and Endothelial Cells.

The maintenance of corneal transparency and normal vision is dependent on preservation of epithelial and endothelial cell layer homeostases. Different types of corneal injury can induce swelling and losses in transparency. Fuchs endothelial corneal dystrophy (FECD) is one type of injury that is commonly treated with rho-associated coiled-coil-containing protein kinase (ROCK) inhibitors. While their clinical benefit is apparent, certain aspects of their mechanism of action require clarification. Specifically, although topical eye drops containing ROCK inhibitors have been employed to treat corneal endothelial dysfunction-associated corneal edema, it remains unclear whether interactions between both corneal epithelial and endothelial cell contribute to mitigating clinical signs that compromise normal vision. To address this question, we first review the intricate ROCK signaling pathways and their role in modulating a variety of functions that are related to the maintenance of corneal transparency and normal vision. We also review the results of ongoing clinical trials employing current FDA-approved ROCK inhibitors, highlighting the prominent role of Y-27632 in the treatment of a variety of ocular conditions, particularly FECD, and its promising results in reversing losses in normal vision through facilitating cell proliferation and suppressing apoptosis. This review shows that the ROCK inhibitor clinical benefit is affected by their interactions between the epithelium and the endothelium. This realization makes it likely that ROCK inhibitors will be approved for use in a clinical setting to treat FECD.

Improving transparency and corneal wound healing in rare diseases by promoting corneal nerve regeneration

Corneal nerves play a crucial role in maintaining the integrity of corneal tissue, as well as the proper regulation of tearing and blinking. When activated, corneal nerves release locally several factors, including neuropeptides, that contribute to the trophic maintenance of corneal tissues. So that, the reduction or absence of corneal nerves led to impaired corneal wound healing in addition to a loss of sensory input, resulting in lack of sensitivity and alterations in tearing and blinking rate. Such consequences are seen clinically in several rare diseases where severe nerve deficit is a prominent factor such as in neurotrophic keratopathy, where the cornea spontaneously ulcerates due to its inability to renew the epithelium and to heal epithelial wounds, leading to loss of corneal transparency. An advanced molecular therapy to increase corneal nerve regeneration and support the corneal neurotrophic environment in such ocular rare diseases is proposed.(Supported by RESTORE VISION – 101 080 611, Horizon Europe Framework Programme, European Commission)

Viral ocular surface inflammation

Viral infections of the ocular surface (OS) may cause chronic, and/or recurrent inflammation that disrupt OS homeostasis, impact quality of life, and potentially impair vision through loss of corneal transparency and/or regularity. In this presentation, we'll review basic and clinical findings underlying OS inflammation in the context of the 3 most common viral pathogens affecting the OS, i.e. Adenovirus, Herpes Simplex virus type 1 and Varicella Zoster Virus.During its acute replicative phase, adenoviral keratoconjunctivitis may trigger severe acute conjunctival inflammation, leading to transmucosal exudation and fibrinous pseudo‐membrane formation. If left untreated, the latter induce conjunctival fibrosis with extensive loss of goblet cells. In a second phase of the disease, antigen‐driven immune‐mediated mechanisms may cause chronic corneal subepithelial infiltration.In the context of HSV and VZV keratitis, OS inflammation is caused by a combination of specific immune response to viral replication, causing stromal infiltration, and neovascularisation and ii) non‐specific inflammatory processes caused by corneal innervation alterations that impact tear secretion and osmolarity. While clinical disease is most often unilateral, unaffected side may display subclinical alterations, including decrease in corneal sensitivity and corneal nerve density, and decrease in endothelial cell density.Management of viral ocular surface inflammation involves a combination of strategies aiming at controlling viral replication, decrease associated inflammatory/immune response and restore OS homeostasia.

Optics and quantitative assessment of corneal transparency

While some optical properties of cornea like its stromal birefringence had been known since the early nineteenth century, theories explaining its transparency remained inconclusive until the publication of David Maurice' emblematic paper in 1957 Maurice made a model calculation of light scattering by a single collagen fibril as a “dielectric needle”. The volume density of the fibrils being known, Maurice could demonstrate that in the absence of any order among the fibrils the cornea would be opaque. Maurice postulated the hexagonal structure which since has been confirmed by electron microscopy. In modern terms, the order among the collagen fibrils within a stromal collagen lamella is described by a “structure factor” in the radiative transfer equation. This term corresponds to a description of the structure in reciprocal space and is thus equivalent to the representation of crystalline lattices in the first Brillouin zone used for structural modelling in crystallography.In a recent study we further analysed the collagen structure of healthy and oedematous corneas on a nanometric level observed by transmission electron microscopy (TEM). By automated image analysis we could retrieve the so‐called “pair correlation function” and calculate light attenuation within the corresponding cornea. Our findings show that the 1/e light penetration depth within healthy cornea could be calculated as 7300 ± 800 μm, which explains well the transparency of healthy cornea. However, the photon mean free path of oedematous cornea turned out to be from two to three times that value. In oedematous cornea, the “dilution” effect of the scatters is in fact stronger than the degradation of transparency by the perturbation of the structure. The actual loss of transparency in oedematous cornea may therefore be attributed to scattering processes at the micrometric level induced by the augmented optical contrast at the sites of the keratocytes between the collagen lamellae.Perturbations in corneal transparency do not only hamper vision, they also impact optical imaging methods on cornea. This, in turn, permits to study the transparency properties of the corneal tissue. One of the main research interests of our group is to analyse corneal images recorded by optical coherence tomography (OCT) and to extract quantitative parameters like photon mean path length and the fraction of coherently transmitted light.Our partners could show that in the light scattering regime, a term in the radiation transfer equation may be neglected and the attenuation of the full field OCT signal in the volume of the tissue reduces to a Lambert–Beer law. We developed a data analysis algorithm based on Bayesian inference to extract the attenuation coefficient and used it for the analysis of ex vivo corneal high‐resolution FF‐OCT images.In a second step, we developed an image processing algorithm for clinical OCT images removing typical artefacts and compensating for inhomogeneous illumination and corneal curvature. We presently are able to extract corneal transparency parameters from routine clinical OCT images and to provide post‐op follow‐up after keratoplasty or other surgical interventions.