bluuebunny/crossref_metadata_2025 huggingface dataset:
Subretinal application of cell cultures: Surgical methods and its transition to the use in human
Authors: Lytvynchuk Lyubomyr
Published: December 2022

The progression of age‐related macular degeneration (AMD) results in irreversible and untreatable impairment of central vision. The formation of the drusen and subsequent atrophy of in the retinal pigmented epithelium (RPE) with development of neovascular membranes remain the typical features of AMD pathogenesis. As the result of the disorganization of the RPE the death photoreceptor cell develops, which is associated with altered RPE phagocytosis, increased RPE permeability, formation of choroidal neovascularization, and involvement of resident and monocytic microglial cells. Nevertheless, the exact cause of the RPE degeneration is still not fully understood. Up to date there is no therapeutic approach, which could reverse the course of AMD progression. Injection of anti‐vascular endothelial growth factors (VEGFs), laser‐photo coagulation and photodynamic therapy of the neovascularisations are being widely used to treat the complications of exudative AMD and therefore to prevent visual loss. Since few decades, the concept of substitutional cell‐based regenerative treatment has been investigated by many groups. It could offer in the near future an alternative approach to restore impaired vision in AMD. Th studies have shown that subretinal implantation of RPE cells seeded on a biodegradable scaffold enhances the integration of the donor cells compared to the injection of cell‐suspension as method of delivery. This could improve the differentiation of donor RPE cells into the host retina and help with the proper cellularization of the RPE monolayer. However, the implantation techniques including surgical procedure with exposion of subretinal space and the development and use of delivery instruments remains challenging. Experimental studies with subretinal RPE transplantation are focused on development of optimal surgical techniques, which could be easily transferred to the application in humans. The cultivation and reproducible viability of hRPEs for transplantation purposes on biodegradable scaffolds for human transplantation shall correspond and be adapted to the instrumentation used during the surgery. Hence, the advances in the methodology and the results of improved approaches shall be investigated further.
The importance of Cajal contribution to the knowledge of the visual system
Authors: de Castro Fernando
Published: December 2022

The Spanish neurohistologist Santiago Ramón y Cajal is universally considered as the founder of modern Neuroscience. His works were fundamental to unravel the structure of the nervous system, coining concepts that transformed the scientific society, opening the door for the scientific exploration of the brain. In his titannic labour, Cajal focused a significant number of his studies on the retina and the visual system, in general, of different species. Maybe the most known among these were the one that he wrote on the retina of the vertebrates (originally published in French, in 1893, which also includes some fundamental discoveries beyond the visual system, like the first description axonal growth cones), or the collaboration with his disciple Domingo Sánchez devoted to the retina and optic centers of the insects (published in Spanish, in 1915). In the present communication, I will try to put these studies in their historical and scientific context, as well as to emphasize the relevance of the visual system for the overall conception of the CNS structure that Cajal gifted to Humanity.
Retinal function: From Cajal drawings to present physiological techniques
Authors: De La Villa Pedro
Published: December 2022

In this Special Interest Symposium we want to present to the European scientific community of retinal researchers the book LA RETINA DE LOS VERTEBADOS. The book was originally published by Santiago Ramón y Cajal in 1892 only in French. Two years later it was translated into German by Richard Greeff and in 1972 it was translated into English by Sylvia Thorpe and Mitchell Glickstein, but it has never been translated into Spanish. We now present the Spanish edition of “La Retina de los Vertebrados” in the context of current knowledge of the functions of retinal neurons. Cajal Figure is widely recognized by physiologists and retinal specialists. However, Cajal's work on the retina and, above all, his masterpiece, “La Retina de los Vertebrados” is not fully known by all the researchers currently working on the physiology of the retina.

In addition, this presentation to the members of EVER, intends to highlight the importance of Cajal's studies in order to understand the physiological mechanisms of the retina. Some classic schemes of retinal cells and their connections will be shown, in which Cajal suggests a series of specific functions for each neuronal element of the retina. In the present work, it will be considered how the methodological advances over the years, and the modern techniques of functional exploration of the nervous system, have allowed us to demonstrate that the functional aspects suggested by Cajal more than one century ago were correct.
Corneal biomechanics for beginners – Understanding the basics
Authors: Sakellaris Dimitris
Published: December 2022

Covering the basic aspects on biomechanical properties of the cornea, my talk will deal with the definition of it. I will refer to both the viscous and the elastic behaviour of the cornea, how these properties change naturally through age and pathologically in case of a corneal diseases. I will briefly analyse basic terms such as visco‐elasticity, stress–strain curve, elastic modulus, stiffness and hysteresis, how these parameters help us understand the corneal tissue better and how this understanding becomes a valuable diagnostic tool.
In vivo evaluation of corneal biomechanics in clinical practice; why, when and how?
Authors: Rechichi Miguel
Published: December 2022

The study of corneal biomechanics in vivo has been evolving fast in recent years. While an organized corneal structure is necessary for its transparency, resistance to occasional external insults and bearing the intraocular pressure (IOP), which several clinically relevant events can disturb.

While significant technological advances have been made for the detection of morphologic markers of keratoconus, these findings are of later sequalae of the disease. Keratoconus is thought to begin with a focal biomechanical weakening of the cornea, followed by a cycle of decompensation resulting in corneal thinning and increased curvature [39, 40]. With the increasing number of corneal refractive surgeries being performed, the identification of the earliest form of the disease, before any morphologic changes have occurred, has become of paramount importance. This has led to efforts directed at measuring the in vivo biomechanical properties of the cornea.

I will speak about techniques currently available for clinical use.

The principles will be discussed along with their strategies to improve accuracy in the IOP measurement, corneal ectasia diagnosis, evaluation of corneal cross‐linking procedures, and planning of corneal refractive surgeries.
Biomechanical profile of refractive procedures; is there a biomechanical privilege?
Authors: Balidis Miltos
Published: December 2022

The cornea shows regional in‐plane variation in strain and deformation. Paracentral and peripheral cornea is stiffer than the central cornea due to differing orientation and number of collagen fibrils. Corneal elastic strength is a function of depth, with decreasing strength from the anterior to the posterior stroma.

During central myopic ablation, an immediate circumferential severing of corneal lamellae is produced. resulting in a forward herniation. Additionally central ablation also relaxes lamellar tension in residual peripheral lamellar segments, which decreases local resistance to swelling leading to peripheral stromal thickening. Expansion of the peripheral stroma may generate centripetal stress in underlying lamellae through dense interlamellar connections at the margin of the ablation zone, resulting central flattening.

Empirically, the hyperopic response is dominant when ablation is limited to the anterior stroma, and progressively deeper circumferential insults result in a shift towards corneal steepening. Central flattening response augments the effects of a myopic procedure but impedes efforts to correct hyperopia.
Preservatives, generics and ocular surface
Authors: Kolko Miriam
Published: December 2022

Most eye drops sold in many European countries are generic. While one would expect generic drugs to be a true copy of the original eye drop, there are surprisingly few requirements for the introduction of a copy eye drop on the market. Thus, only the concentration of the active ingredients should be identical to the concentration of the original product. Since many other factors such as bottle material, bottle shape and size and lid colour, droplet size, pH, viscosity, buffer capacity can affect the effect, there is concern about whether generics are identical to their original variants. In addition to the few requirements for the introduction of generic drugs, the replacement of preservatives in eye drops with the same active substance is legal. In general, preservatives have a negative effect on the surface of the eye due to their toxic effect on, among other things, the ocular surface cells and on the tear film. Here, a brief overview of the concerns and facts about generics and the use of preservatives in eye drops will be given.
IOP measurement in abnormal corneas
Authors: Grieshaber Matthias
Published: December 2022

Elevated intraocular pressure still the major surrogate and risk factor for development and progression of glaucoma. For decades the Goldmann applanation tonometry has been the gold standard for measuring intraocular pressure; however, there are newer methods of measuring intraocular pressure, each one has advantages and disadvantages and depends on the corneal biomechanics parameters. This talk will focus on the different methods and their limitations with regard to measuring intraocular pressure in abnormal corneas.
Development of 3D‐printed devices for the study of transscleral drug delivery on freshly excised whole porcine eyes
Authors: González‐Fernández Felipe M. , Cauzzi Daniele A. , Nicoli Sara , Gasco Paolo , Pescina Silvia
Published: December 2022

Purpose: Ex vivo ocular models are a valuable tool for quick screening ophthalmic formulations through permeation and retention studies. We hereby present a 3D‐printed set‐up consisting of a combination of two devices, allowing for the ex vivo study of transscleral drug delivery with fresh whole swine eyes.

Methods: The two devices were drafted on a CAD (computer aided design) software and 3D printed with three different printing techniques: selective laser sintering (SLS), fused deposition modelling (FDM) and masked stereolithography (MSLA). The first device was designed to guarantee the contact between drug formulation (liquid or semisolid) and the scleral surface in a defined permeation area for up to 24 h. The second device was then designed to maintain up to three ocular bulbs at constant temperature (37°C) and humidity values.

Results: MSLA 3D printing technique was selected due to its versatility, superior print detail and a low unitary cost. In addition, the other two explored techniques delivered relatively porous prints that do not guarantee the required water and air tightness of the devices. The first device was optimized in order to maximize adherence onto the scleral surface and thus anatomically adjusted to porcine scleral curvature. Firm anchorage onto the ocular surface was achieved through a ring‐shaped vacuum chamber easily controlled with a syringe. The second device allowed to immobilize the ocular bulb during the experiment, preserve ocular hydration, and maintain a fixed working temperature by placement into a water bath.

Conclusions: The developed ex vivo set‐up, based on the whole porcine eye, could be suitable to perform permeation and accumulation studies of transscleral applied ocular formulations.
In vivo identification of Schlemm's canal and response to SLT
Authors: Gupta Shikha
Published: December 2022

ASOCT has been used to demonstrate a lack of Schlemm's canal (SC) or its dysgenesis in many Primary Congenital Glaucoma (PCG) eyes, and nearly half of Juvenile Open Angle Glaucoma (JOAG) eyes. There is an increasing evidence that even in adult‐onset POAG, apart from the trabecular meshwork (TM), the post TM structures like the SC and collector channels are also affected which may contribute to the outflow resistance. Absence or dysgenesis of the SC is expected to be associated with a poor outflow facility.

We evaluated the response of Selective laser trabeculoplasty (SLT) and correlated the visibility of SC on ASOCT in eyes with JOAG. This is because we had previously observed that only 40% of patients diagnosed with JOAG respond to SLT. In this study, we observed that detection of SC on ASOCT among patients undergoing SLT, (even without having evident angle dysgenesis on gonioscopy) was a significant predictor deciding the response to SLT. Success of SLT was defined as a reduction of IOP by 20% or more from pre‐laser value at 6‐months follow‐up without any further IOP‐lowering medication or surgery. A successful reduction in IOP at six‐month follow‐up was correlated with the extent of angle dysgenesis on ASOCT (ADoA).

We observed that presence of SC was associated with 8.3 times greater chances of success of SLT than its absence. Also if the presence of SC was detected in >50% ASOCT scans in one eye, it was associated with 21.4 times greater chances of SLT success (p = 0.009). Hence in vivo imaging of the angle is a non‐invasive method of detecting angle dysgenesis, in the absence of an apparent goniodysgenesis. It may help in selecting potential candidates for SLT (or other angle based surgeries) by predicting possible outcome and thus providing more realistic expectations when advising patients, regarding the likelihood of success /failure of their treatment.
In vivo identification of angle dysgenesis
Authors: Mahalingam Kathikeyan
Published: December 2022

Anterior segment Spectral domain–optical coherence tomography (SD‐OCT) is being increasingly used in glaucoma patients, primarily to investigate the anterior chamber angle and visualize the trabecular meshwork (TM) and Schlemm's canal (SC) in vivo. With the advent of angle surgery for glaucoma much interest has been generated in the aqueous outflow pathways. Our studies have shown that in vivo imaging of anterior chamber angle with ASOCT can been used to detect gross features of angle dysgenesis in primary congenital glaucoma (PCG), juvenile onset open angle glaucoma (JOAG) and adult onset primary open angle glaucoma (POAG), which has been described either as an absence of SC and/or the presence of abnormal tissue or a hyper‐reflective membrane within angle recess. This membrane is similar to what Barkan had described in PCG and was later described to be an angle cicatrization that portends a poorer success with goniotomy. Absence of development of SC was also shown by Hollander et al to be associated with a severe form of goniodysgenesis while its presence was seen in less severe goniodysgenesis on histopathological studies involving PCG. In fact, angle dysgenesis on ASOCT (ADoA), can be observed even in eyes with gonioscopically normal appearing angles. It is known that gonioscopy provides only a superficial representation of the histopathological anomalies affecting the angle. The presence of a thick compact tissue in the TM samples of Juvenile glaucoma patients has been observed, irrespective of whether they had an apparent goniodysgenesis or not. Hence, what appears to be morphologically normal angle on gonioscopy may harbour dysgenesis of the TM or even the SC. Primary congenital glaucoma, JOAG and adult onset POAG form a spectrum in terms of severity of angle dysgenesis. While most of the PCG eyes have features of ADoA, the same are present in 40% of JOAG eyes and in up to 35% of adult onset POAG. The size of the SC has also shown to be decreased in patients with adult‐onset open angle glaucoma based on in vivo OCT studies. We also present interesting observations of angle dysgenesis in fellow eyes of children with unilateral PCG.
Ocular surgical use of autologous platelet‐rich plasma
Authors: Rodriguez Alejandra E.
Published: December 2022

Eye platelet‐rich plasma (E‐PRP) concentrates platelets in a small volume of plasma which contains a high concentration of important growth factors and cell adhesion molecules. These cell adhesion molecules and growth factors occupy a major role in wound healing and enhance the physiological procedure at the site of the injury or the surgery. Platelet‐rich plasma in the form obtained in ophthalmology, E‐PRP, is a reliable and effective surgical coadjuvant to promote corneal wound healing in severe corneal ulcers and corneal perforations and may be associated with other ocular surface reconstruction procedures.

Actually, platelet‐rich plasma (E‐PRP) offers new surgical perspectives in many fields of medicine helping in wound healing, it represents a greater similarity to the natural healing process as a composite of multiple growth factors, is safe due to its autologous nature and has both mitogenic and chemotactic properties. E‐PRP functions as a drug delivery system and a tissue sealant.

The α‐granules within these platelets liberate platelet‐derived growth factors, platelet‐derived growth factor BB (PDGF‐BB), transforming growth factor β1 (TGF‐β1), epidermal growth factor (EGF), and vascular endothelial growth factor A (VEGF‐A) which have an important anti‐inflammatory action. It has many ocular surface applications such as in dry eye, dormant corneal ulcers, and it is also used surgically as a sutured clot of autologous fibrin membrane in big neurotrophic corneal ulcers or imminent/already perforated eyes.

There are new uses of E‐PRP such as the intracameral application of E‐PRP for different purposes or injection into the lacrimal glands. All of them with the aim of improving the functionality of damaged eye tissue.
A novel approach of increasing bioavailability of drug molecules to the posterior ocular segment through topical administration using penetration enhancing agents
Authors: Thareja Abhinav , Leigh Thomas , Hakkarainen Jenni J. , Alvarez‐Lorenzo Carmen , Hughes Helen , Fernandez‐Trillo Francisco , Blanch Richard J. , Ahmed Zubair
Published: December 2022

A major cause of blindness worldwide is disease and damage in the posterior ocular segment. Due to poor penetration of therapeutic molecules, topical eye drops tend to be the least effective. We demonstrate a potential approach of penetration enhancement in topical drug formulations for such diseases using three penetration enhancing agents (PEAs) — an in‐house synthesized novel helical polymer and two commonly used cell penetrating peptides (CPPs), TAT and Penetratin, to enable increased penetration of the most commonly used anti‐inflammatory drug, dexamethasone sodium phosphate (DSP). A rapid and cost‐effective ex‐vivo screening model of excised porcine cornea and sclera is used to assay trans‐corneal/scleral penetration of the three PEAs and results quantified using UV & fluorescence spectroscopy for PEAs and by high performance liquid chromatography (HPLC) for DSP. All three PEAs effectively cross both the cornea and sclera individually. A significant enhancement of DSP trans‐corneal/scleral permeation after topical application with PEAs is observed. ZO‐1 immunostaining of the tight junctions in corneal epithelium demonstrated intact tight junctions and transepithelial electrical resistance (TEER) measurements of the corneal epithelium before and 60 minutes after application show very negligible to no difference, thus proving no damage has been done to the integrity of corneal barrier and barrier function. Finally, in‐vitro cytotoxicity of PEAs was determined using MTT assays in ARPE‐19 and HCE‐2 cells, whilst immunostaining with β‐III tubulin was used in assays involving adult rat primary retinal neurons. None of the PEAs exhibit any trace of cytotoxicity. We conclude that CPPs are able to increases the efficiency of drug delivery through the cornea and improve the chances of drug delivery to the posterior ocular segment.
Restoring vision in blind patients: From optogenetic to sonogenetic therapies
Authors: Picaud Serge
Published: December 2022

Visual restoration is certainly the greatest challenge for brain‐machine interfaces with the high pixel number and high refreshing rate. In the recent year, we brought retinal prostheses and optogenetic therapy up to successful clinical trials. Optogenetics relies on the expression of a microbial opsin in residual neurons by gene therapy. These strategies can provide some vision in blind patients with diseases of photoreceptors such as retinal dystrophies or age‐related macular degeneration. They can reintroduce some information in at the retinal level by activating residual neurons after the loss of photoreceptors. For patients with optic nerve atrophy as in glaucoma and diabetic retinopathy, visual restoration requires the direct activation of the visual cortex. However, cortical prostheses have shown efficacy for limited periods of time and limited pixel numbers.

In the present project, we are investigating a novel approach to restore vision at the cortical level with sonogenetic therapy. This approach relies on expressing an ultrasound‐sensitive ionic channel in cortical neurons to imprint images at this level by ultrasound stimulations.

The Mscl ionic channel fused to the tdTomato reporter gene was expressed in the visual cortex of rats following a cortical AAV injection. The channel expression was indicated by the red fluorescence of tdTomato. Recording with penetrating electrodes indicated responses to cortical ultrasound stimulation with a high temporal resolution but a shorter latency than natural visual responses. In the absence of AAV injection, the visual cortex was not responsive to ultrasounds. Moving the ultrasound stimulator moved the activated area as indicated by Ecog electrode array recording. Finally, mice having learned to associate a flash of light to a water delivery responded similarly to an ultrasound cortical stimulation if the MscL protein was expressed in their cortex.

These results indicate that the MscL channel induces an ultrasound sensitivity of cortical neurons generating a cortical activations with a spatiotemporal resolution suitable for vision restoration and perceived as phosphenes. Further studies will have to demonstrate true vision of forms by this sonogenetic approach prior to a clinical translation.
Immunomodulation for retinal degenerations
Authors: Langmann Thomas
Published: December 2022

This talk highlights the role of key immune pathways in the pathophysiology of major retinal degenerative diseases including age‐related macular degeneration. We will first discuss the mechanisms how loss of retinal homeostasis evokes an unbalanced immune reaction involving responses of local microglia and recruited macrophages. Presenting these innate immune cells as targets, we specifically emphasize the concept of immunomodulation as potential treatment strategy to prevent or delay vision loss. Promising molecules are ligands for phagocyte receptors, intracellular regulators involved in the activation of microglia and more general modifiers of their inflammatory response and migration. We briefly summarize the scientific evidence for this strategy from preclinical animal models, human ocular tissue analyses, and clinical trials evolving in the last few years.
Neuroprotective effects of intraocular bone marrow‐derived mononuclear cell transplants in inherited retinal degenerations
Authors: Di Pierdomenico Johnny , Ayuso Diego Garcia , Sanz Manuel Vidal , Perez Maria Paz Villegas
Published: December 2022

Inherited retinal degenerations are diseases characterized by photoreceptor loss secondary to genetic defects. At present, only a minority are susceptible of genetic treatment and therefore are a frequent cause of blindness in infancy and adulthood.

Retinitis Pigmentosa (RP) is the most frequent inherited retinal degeneration. This disease has a prevalence of around 1 in 4000 individuals and is caused by mutations in more than 300 genes. RP is characterized by progressive loss of photoreceptors, rods and then cones that may die secondarily to rod loss.

The rats P23H and Royal college of Surgeon (RCS) are two well characterized animal models of RP because they bear genetic defects observed in RP patients. The P23H rat suffers an autosomal dominant mutation of the rhodopsin gene that causes protein misfolding and endoplasmic reticulum stress in rods, which die first followed by cones. The RCS rat has a mutation of MERTK gene, that impedes the normal photoreceptor outer segment phagocytosis by RPE cells thus causing simultaneous rod and cone degeneration.

Therapies for inherited photoreceptor degeneration aim to prevent or delay death of the photoreceptors, or in specific circumstances try to replace them.

The Bone marrow derived‐mononuclear cells (BM‐MNCs) are a mononuclear CD34+ subpopulation of bone marrow‐derived cells that can be separated from the other cellular fractions of the bone marrow aspirate using a Ficoll density gradient‐based protocol. The BM‐MNCs is a mixture of specific bone marrow cell subtypes in which is possible to find cells: Lin+, Lin−, CD34+, c‐Kit+, CD133+ or Sca‐1+ HSCs, endothelial precursor cells, and Mesenchymal Stem Cells.

BM‐MNCs transplantation has shown promising results in different animal models of neuronal degeneration, including inherited photoreceptor degenerations.

In our studies we have performed a syngeneic intravitreal or subretinal transplantation of BM‐MNCs in a P23H‐1 and RCS rats, and we have documented that both increase photoreceptor survival. They also improve the morphology of the photoreceptors outer segment, decrease synaptic degeneration in the outer plexiform layer and reduce glial fibrillary acidic protein (GFAP) expression in Müller cells. However, the transplanted cells did not penetrate the retina, only survived for up to 15 days, and did not modify microglial cell activation and migration or the electroretinographic responses. Their beneficial effects are maybe due to a paracrine trophic effect achieved through release of neurotrophic, anti‐angiogenic and/or immunomodulatory factors.

In conclusion, the intra ocular transplantation BM‐MNCs shows photoreceptor neuroprotective actions in inherited retinal degenerations. These cells may have the potential to slow down photoreceptor loss, and therefore could be indicated for treatment of the early stages of photoreceptor degenerations.
Pharmacological strategies in retinal dystrophies
Authors: Maneu Victoria
Published: December 2022

The therapeutic options for a patient affected by a retinal degenerative disease are discouraging. Despite several clinical trials show promising results, we still need to go a long way until the arrival to the clinics of therapies that could partially restore the retinal functionality, as optogenetics, or stem cell transplant, or, even better, that cure the disease by targeting its aetiology, as gene therapy. Until these therapies reach clinical success, targeting key factors in the degenerative process could temporarily slow its progression. Although there are many different retinal degenerative diseases, with different aetiology and clinical evolution, the degenerative process is always accompanied by common biochemical and molecular factors, it does not matter if the degeneration has a genetic cause, as it happens in inherited retinal dystrophies as retinitis pigmentosa, Leber congenital amaurosis or Stargardt disease; or if it is a multifactorial disease as age‐related macular degeneration; or if it is secondary to other pathologies, as diabetic retinopathy. The high metabolic rate of the retinal cells, their continuous exposition to high oxygen levels and light‐induced stress are key factors in the development of the degenerative process. When retinal cells start to die, activated glial cells secrete proinflammatory cytokines, chemokines and trophic factors that worsen the degenerative process. Thus, trying to reduce the oxidative stress and inflammation that are always present in the degenerating tissue seems a good approach to be tried. Moreover, considering the great number of mediators involved in the degenerative process, a widest approach combining therapies with antioxidant, anti‐inflammatory and antiapoptotic molecules, as well as neurotrophic factors could slow the progression of the disease and preserve the visual capacity for a certain time. Moreover, even when the vision has been completely lost, the neuroprotection could improve other non‐visual functions, like the control of circadian rhythms and pupil contraction and could also influence the patient's memory and mood. It is also relevant to note that this therapy can keep a healthy tissue and provide an adequate environment of healthy cells that will help to the clinical success of other techniques as cell transplant or optogenetic approaches, which could hardly be successful in a damaged tissue surrounded by dying cells.

Supported by: Spanish Ministry of Science and Innovation (MICINN‐FEDER PID2019‐106230RB‐I00) Generalitat Valenciana (PROMETEO/2021/024).
Contribution of intraocular pressure‐dependent and pressure‐independent glaucoma models to neuroprotection
Authors: Aviles‐Trigueros Marcelino
Published: December 2022

Glaucoma is considered a heterogeneous group of degenerative optic neuropathies characterized mainly by an ongoing loss of retinal ganglion cells (RGCs) which causes progressive deterioration of the visual field and irreversible blindness. The aetiology and pathophysiology of glaucoma are not known in detail and are a matter of debate. Although the most significant risk factor in the development and progression of glaucoma correlates with elevated intraocular pressure (IOP), at present the only treatment available to prevent or delay its development is to reduce IOP by medication or surgery to slow its detrimental effects. But reducing IOP alone does not stop the progression of the disease. Therefore, IOP may not be the only motive for glaucomatous retinopathy and optic neuropathy, and there could be other hidden mechanisms contributing to the loss of RGCs.

A suitable animal model of neurodegenerative disease, such as glaucoma, should be easy to induce and reproduce, feasible and predictable, and allow detection and quantification at the biochemical, morphological and functional levels of the induced pathological changes. However, no model emulates all aspects of a pathology such as glaucoma, which is likely to have more than one aetiology and manifest itself through different pathological mechanisms. Hence, the interest and need to establish and use different experimental models in rodents to improve our understanding of the pathophysiology of glaucoma and to investigate possible neuroprotective agents. In general, experimental models of glaucoma established in rodents involve a transient or chronic increase in IOP above normal values, which allows us to study the pathological changes associated with ocular hypertension. However, elevated IOP may not be the only cause of glaucomatous retinopathy and optic neuropathy, hence the need for models that do not involve an increase in intraocular pressure to deal with specific issues of the evolution of this pathology, such as optic nerve injury, retinal ischaemia/reperfusion, intravitreal injection of excitatory amino acids or endothelin‐induced optic neuropathy.

Results obtained in different experimental models of glaucoma mimicking ocular hypertension or optic nerve damage have confirmed the existence of morphofunctional differences in the time course of RGC loss, both between different types of RGCs and between different lesions. As well as the effects on other retinal cell populations. In this regard, in the outer retina, there is a significant contrast between damage caused by ocular hypertension and optic nerve injury. Both axotomy and ocular hypertension induce a selective loss of RGCs, but ocular hypertension also promotes a loss of photoreceptors.

Thanks to the different glaucoma models studied, the findings obtained have contributed to improving our knowledge of glaucomatous pathology and to the development of future neuroprotective therapies.
I‐VISION project. A new step in artificial vision
Authors: Garrido Jose Antonio
Published: December 2022

The i‐VISION project aims to develop next‐generation of retinal prosthesis technology in efforts to restore high‐acuity artificial vision to individuals blinded by retinal degeneration. Retinal prostheses operate by electrically stimulating retinal neurons that survive the degeneration in a spatiotemporal pattern that is interpreted by the brain as vision. Presently, the challenge to implement thousands of small‐diameter electrodes and increasingly more sophisticated stimulation protocols that can adapt to the patients' needs has not been met, which severely limits the quality of restored vision in current retinal prostheses.

In this presentation I will present how i‐VISION is set to address some of the challenges hindering the performance of current retinal prostheses, with a focus on the use of revolutionary miniaturized electrode nanotechnology based on graphene. Graphene microelectrodes are capable of mediating high‐charge injection highly localized that will improve the spatial resolution at the neural interface, and locally monitoring the stimulation efficacy, allowing a future adaptive therapy strategy. In addition, I will present work of the i‐VISION consortium on the use of advanced in vitro and in vivo imaging techniques of the evoked retinal and cortical responses to quantify the area of neurons activated by the electrical stimulation, with the ultimate goal of generating maps of retina‐visual cortex interconnectivity.
New trends in retinal imaging
Authors: Cordeiro Francesca
Published: December 2022

Latest advances in ophthalmic imaging includes their recognition as biomarkers. Biomarkers are increasingly used in medicine as indicators of a disease and treatment response. The eye lends itself to providing different biomarkers as structural indicators of pathology. In addition to uses of OCT, new and emerging technologies including OCTA, AO, multispectral imaging, polarizarition techniques, fluorescent imaging including FLIO, curcumin and DARC will be discussed, as will their applications to glaucoma, retinal and neurodegenerative conditions.
From mouse to primate: Retinal circuit disassembly and plasticity in glaucoma
Authors: Ou Yvonne
Published: December 2022

Precise connections between synaptic partners are shaped during development to ensure proper neural circuit function, but how these connections are disassembled and rearranged after injury is less well understood. In glaucoma, the ganglion cell is injured but very little is known about how the presynaptic circuitry is perturbed. Furthermore, the ability to diagnose and treat glaucoma at an optimal stage before irreversible retinal ganglion cell loss occurs requires a comprehensive understanding of inner retina circuit disassembly and plasticity. Recent studies in rodent, including our work, suggest that specific ganglion cell types are more vulnerable to glaucomatous injury. In this talk I will discuss the specificity and timing of anatomic retinal circuit disassembly in mouse and primate experimental glaucoma and the potential for the adult diseased retina to exhibit plasticity. This work expands our knowledge of how adult neural circuits react and rearrange in the face of injury and permits the design of novel psychophysics testing paradigms and ganglion cell neuroprotection or regeneration strategies.
Modelling complex retinal disease with a large scale patient induced pluripotent stem cell approach
Authors: Pebay Alice
Published: December 2022

To assess the transcriptomic profile of disease‐specific cell populations, fibroblasts from patients with geographic atrophy – the advanced form of age‐related macular degeneration – were reprogrammed into induced pluripotent stem cells (iPSCs) before being differentiated into retinal pigment epithelium (RPE) cells and compared to those from healthy individuals. RPE cells were subjected to single‐cell RNA‐sequencing and to mass spectrometry, to precisely characterize their transcriptomic and proteomic profiles. This approach implicated genes at loci definitively associated with disease, and uncovered new pathogenic pathways, which were subsequently confirmed by functional analysis. This work highlights the power of large‐scale iPSC studies to uncover context‐specific profiles for genetically complex disease such as age‐related macular degeneration.
Müller‐retinal ganglion cell interactions
Authors: Vecino Elena , Pereiro Xandra , Ruzafa Noelia
Published: December 2022

Glaucoma is a neurodegenerative disease and the leading cause of irreversible blindness in the world, whose main risk factor is increased intraocular pressure. When visual problems are first detected in patients with glaucoma, already half of the retinal ganglion cells (RGCs), the neurons that send visual information from the eye to the brain, have died principally in the peripheral retina. The timeframe of cell death is prolonged, lasting even decades after an initial diagnosis. Müller glia (MG) are the main macroglial cell in the retina, play prominent roles regulating normal and pathological physiology and react to neuronal injury in glaucoma. The change to a reactive phenotype of MG initiates signalling cascades that may serve a neuroprotective role but may also proceed to promote damaging effects on RGCs. However, the underlying mechanisms and signalling pathways that specifically promote protective versus destructive roles of reactive glial cells are mostly unclear.

Our main hypothesis is that MGs exert an important role in the death of RGCs in glaucoma with the MGs in the periphery being the most sensitive to intraocular pressure, promoting the death of RGCs. Preventing MG response to elevated pressure, MG can neuroprotect RGCs in early stages of glaucoma.

We have proved in vitro, that in control condition MG secret neuroprotective factors, and under elevated pressure MG are the responsible for the RGCs death, being less sensitive to the elevated hydrostatic pressure (EHP) the MG present in the central retina. Moreover, stretch‐activated nonselective TRPV4 cation channels present in MG are differently activated by the pressure depending on their location within the retina. Proteomic analysis from the conditioned media (CM) of MG revealed different protein expression levels being more pronounced in the CM from MG from peripheral retina in EHP. Proteins identified correspond mainly to functions such as: apoptosis, oxidative stress, inflammation and angiogenesis.

We conclude that the different sensibility of the RGCs to pressure in glaucoma could be related with the different activation of the neighbours MG.

Supported by ELKARTEK (KK‐2019/00086), MINECO‐Retos (PID2019‐111139RB‐I00) and PIBA (2020_1_0026).
Amniotic membrane (AM) for ocular surface pathology: The old and the new
Authors: Herrera Josè M.
Published: December 2022

The first amniotic membrane use was dated in 1910 as a skin graft substitute material. In the ophthalmological field, it was first used in the 1940 s as a conjunctival substitute after removal of fibrotic tissue, with good results when it was contracted with rabbit peritoneum. The procedure lost interest because the tissue could only be used fresh. Clinicians regained interest in the early 1990 s when new preservation, storage and distribution methods were already available.

Application methods: The way to use the amniotic membrane depends on the pathological situation for which it is indicated. The depth, shape and size of the recipient area also play a role in the therapeutic decision.

In general, there are three possible situations:

An inlay transplantation as a graft: The AM works as a replacement of the lost tissue because it is remodelled into the host corneal matrix over time. The amnion is placed epithelial side up, as the membrane is able to act as a substrate for epithelial regeneration.

An onlay transplantation as a patch: The transplant acts as a temporary biological bandage. The AM and the molecules that produces, protect the cornea from environmental aggressions, and it also has antifibrotic effect. The amnion is placed epithelial side down. Usually the product can be removed, although it is usually self‐degraded.

Combinatorial transplantation as a sandwich: Two layers are transplanted, the deepest is placed epithelial side up and the other epithelial side down, obtaining the benefits of the two techniques.

The graft provides structural integrity and the patch gives protection to de the graft, while the epithelium is expected to grow between the two layers.

From our point of view this is the best option.

Main indications as a graft:

‐Corneal ulcerations and persistent epithelial defects.

‐Limbal Stem Cells Deficiency (LSCD). It can be used in Simple Limbal Epithelial Transplantation (SLET), in Amnion‐Assisted Epithelial Redirection (ACER), and as a matrix for Cultivated Stem Cell Transplantation.

‐In Glaucoma, to treat leaks from blebs.

‐In Neoplasias, AM is used to act as a substrate for conjunctival migration and reconstruction following excision of both malignant and benign tumours.

‐In Oculoplastic surgery, AM has been suggested as a potential alternative to mucosal membrane transplantation in lid revision, orbital linings or symblepharolysis.

‐In Pterygium surgery, mainly in relapsing cases in which a very large resection of the conjunctiva is made.

‐In Strabismus surgery, either to cover defects or to reduce muscle fibrosis and adhesion.

Main indications as a patch, for Ocular Surface Wound Healing:

‐In the acute stage of Chemical/Thermal injuries.

‐In the acute stage of Cicatrising Conjunctivitis (Erythema Multiforme Diseases, Pemphigoid, Graft versus Hosts Disease).

‐In recurrent corneal erosions.

The potential risks of amniotic transplantation will be discussed.
Lyophilized amniotic membrane for corneal ulcer and post operative cross‐linking
Authors: Knoeri Juliette
Published: December 2022

Patients with progressive keratoconus, especially in the early part of life, may benefit from crosslinking to accelerate the polymerization of corneal collagen, thus increasing the biomechanical strength of the cornea. The reference crosslinking protocol, recognized as the most effective in stabilizing the disease, corresponds to a classic crosslinking protocol with de‐epithelialization (epi off). This technique is pro‐inflammatory in patients who often have associated allergic keratoconjunctivitis. It is also painful postoperatively despite the systematic application of a dressing lens since it requires corneal de‐epithelialisation. The allergic background can lead to delays in healing with postoperative infections. Amniotic membranes have already been used in post refractive surgery. Their application in post‐crosslinking protocol epi off, directly on the patient's cornea without suture under a therapeutic contact lens, would reduce the intensity of pain after the procedure, complications such as infectious keratitis, sterile infiltrates, superficial or deep haze, aseptic corneal necrosis (thinning and fibrosis, perforation described), endothelial damage due to probable excessive free radical toxicity (reversible corneal decompensation or requiring a corneal graft), delayed epithelial healing (association of dry syndrome or blepharitis) and viral reactivation (Herpes Simplex virus or HSV). The amniotic membrane by its anti‐angiogenic, healing, anti‐inflammatory and anti‐infectious properties seems to have a decrease in post‐operative pain and an acceleration of corneal epithelial healing as in superficial corneal ulcers.
Amniotic membrane as a substrate and delivery vehicle for stem cells
Authors: Calonge Margarita
Published: December 2022

New therapeutic concepts and clinical strategies are emerging for the different kinds of human amniotic membranes (hAM). There are new commercial forms of hAM that are under investigation for old and new applications, from ocular surface epithelial persistent defects to the hAM extract eyedrops or the new use of hAM as a delivery platform and substrate for stem cells for ocular surface repair.

Although there are more substrates used as support for growth, maintenance, and delivery of cultivated stem cells onto the ocular surface, hAM is still the most used universally, followed by fibrin‐based substrates. This is due to the notable biological properties of this live tissue. The only disadvantage may be that it must come from tissue banks and as such, there can be some shortages and the cost is not irrelevant.

Several other types of synthetic substrates such as lotrafilcon A, siloxane hydrogels or poly lactide‐co‐glycolic acid (PLGA) polymers, have been used over the last years to facilitate cell culture and the subsequent transplantation onto the ocular surface. In addition, several polymeric biomaterials like polycaprolactone, polylactic glycolic acid, chitosan and gelatin membranes, collagen or elastin‐like polymers are being also used to support ocular epithelial cells in preclinical studies. However, none of those attempts to substitute hAM have been translated inti clinical use.

We have successfully used hAM as substrate and delivery platform in preclinical research, both in vitro and in vivo models of stem cell deficiency, and in the two clinical trials that have been completed and published, with both cultivated epithelial cells from the limbal niche and bone marrow‐derived mesenchymal stem cells.
natural treatment for dry eye disease
Authors: Messmer Elisabeth M.
Published: December 2022

Standard recommendations for Dry Eye Disease (DED) are part of many national and international guidelines. However, many patients wish to substitute or add natural treatments to their regimen for DED. These include natural ingredients such as Manuka honey, Aloe vera, and Green Tea extract. In addition, human body ‘products’ such as autologous blood, human breast milk, urine and faeces are used in the treatment of DED. Studies evaluating these natural treatments are scarce, and information for self‐production and use are often communicated through the internet. This presentation will give an overview on existing information concerning this hot topic.