Systemic treatment with cigarette smoke extract affects zebrafish visual behaviour, intraocular vasculature morphology and outer segment phagocytosis.

Introduction: Cigarette smoking adversely affects multiple aspects of human health including eye disorders such as age-related macular degeneration, cataracts and dry eye disease. However, there remains a knowledge gap in how constituents of cigarette smoke affect vision and retinal biology. We used zebrafish to assess effects of short-term acute exposure to cigarette smoke extract (CSE) on visual behaviour and retinal biology. Methods: Zebrafish larvae with a developed visual system at three days post-fertilization (dpf) were exposed to CSE for 4, 24 or 48 hours. Visual behaviour, hyaloid vasculature morphology, retinal histology, oxidative stress gene expression and outer segment phagocytosis were investigated using visual behavioural optokinetic and visual motor response assays (OKR and VMR), microscopy (light, fluorescence and transmission electron microscopy), and real-time PCR. Results: In zebrafish larvae, 48 hours of CSE treatment resulted in significantly reduced visual behaviour. Larvae treated with 10, 15 or 20 µg/mL CSE showed an average of 13.7, 10.7 or 9.4 saccades per minute, respectively, significantly lower compared with 0.05% DMSO controls (p=0.0093, p=0.0004 and p<0.0001, respectively) that exhibited 19.7 saccades per minute. The diameter of intraocular vessels increased from 4.833 µm in 0.05% DMSO controls to 5.885 µm in the 20 µg/mL CSE-treated larvae (p=0.0333). Biometry analysis highlighted a significant axial length elongation in 20 µg/mL CSE-treated larvae (216.9 µm, p<0.0001) compared to 0.05% dimethyl sulfoxide (DMSO) controls (205.1 µm). Larvae exposed to 20 µg/mL CSE had significantly (p=0.0002) higher numbers of RPE phagosomes compared to vehicle controls (0.1425 and 0.093 phagosomes/µm RPE, respectively). Conclusions: Zebrafish larvae with a developed visual system display apparent defects in visual behaviour and retinal biology after acute exposure to CSE, establishing a valuable in vivo model to investigate ocular disorders related to cigarette smoke.

This study investigates the effects of cigarette smoke on the visual system of zebrafish larvae. We exposed the larvae to cigarette smoke extract for 4, 24, or 48 hours and assessed their eye movements, retina morphology and oxidative stress gene expression. Exposure to cigarette smoke extract for 48 hours reduced eye movements behaviour in the zebrafish larvae and led to changes in the morphology of their hyaloid vasculature present in the lens and the number of phagosomes in their retinal pigment epithelium. When exposure was shortened to 4 or 24 hours, eye movements were still reduced and oxidative stress was affected. These results suggest that zebrafish larvae can be used as a valuable model to investigate ocular disorders related to cigarette smoke.

Affordable and effective optokinetic response methods to assess visual acuity and contrast sensitivity in larval to juvenile zebrafish.

The optokinetic response (OKR) is an effective behavioural assay to investigate functional vision in zebrafish. The rapid and widespread use of gene editing, drug screening and environmental modulation technologies has resulted in a broader need for visual neuroscience researchers to access affordable and more sensitive OKR, contrast sensitivity (CS) and visual acuity (VA) assays. Here, we demonstrate how 2D- and 3D-printed, striped patterns or drums coupled with a motorised base and microscope provide a simple, cost-effective but efficient means to assay OKR, CS and VA in larval-juvenile zebrafish. In wild-type, five days post-fertilisation (dpf) zebrafish, the 2D or 3D set-ups of 0.02 cycles per degree (cpd) (standard OKR stimulus) and 100% black-white contrast evoked equivalent responses of 24.2±3.9 or 21.8±3.9 saccades per minute, respectively. Furthermore, although the OKR number was significantly reduced compared to the 0.02 cpd drum (p<0.0001), 0.06 and 0.2 cpd drums elicited equivalent responses with both set-ups. Notably, standard OKRs varied with time of day; peak responses of 29.8±7 saccades per minute occurred in the early afternoon with significantly reduced responses occurring in the early morning or late afternoon (18.5±3 and 18.4±4.5 saccades per minute, respectively). A customised series of 2D printed drums enabled analysis of VA and CS in 5-21 dpf zebrafish. The saccadic frequency in VA assays was inversely proportional to age and spatial frequency and in CS assays was inversely proportional to age and directly proportional to contrast of the stimulus. OKR, VA and CS of zebrafish larvae can be efficiently measured using 2D- or 3D-printed striped drums. For data consistency the luminance of the OKR light source, the time of day when the analysis is performed, and the order of presentation of VA and CS drums must be considered. These simple methods allow effective and more sensitive analysis of functional vision in zebrafish.

Ocular Manifestations of Alzheimer's and Other Neurodegenerative Diseases: The Prospect of the Eye as a Tool for the Early Diagnosis of Alzheimer's Disease.

Dementia, including Alzheimer's disease (AD), is a major disorder, leading to several ocular manifestations amongst the elderly population. These visual disorders may be due to retinal nerve degenerative changes, including nerve fibre layer thinning, degeneration of retinal ganglion cells, and changes to vascular parameters. There is no cure for Alzheimer's, but medicines can slow down the development of many of the classic symptoms, such as loss of memory and communication skills, mood swings, and depression. The disease diagnosis is difficult, and it is only possible through PET scans of the brain, detecting evidence of the accumulation of amyloid and tau. PET is expensive and invasive, requiring the injection of radioactive tracers, which bind with these proteins and glow during scanning. Recently, scientists developed promising eye-scan techniques that may detect Alzheimer's disease at its earliest stage, before major symptoms appear, leading to improved management of the disease symptoms. In this review, we are discussing the visual abnormalities of Alzheimer's and other neurodegenerative diseases, focused on ocular functional-visual-structural biomarkers, retinal pathology, and potential novel diagnostic tools.

Therapeutic inhibitors for the treatment of dry eye syndrome.

INTRODUCTION: Dry eye disease (DED), defined as a multifactorial disease of tears and ocular surface, results in symptoms of discomfort, ocular irritation, visual disturbance and tear film instability. This syndrome is accompanied of ocular surface inflammation and it is produced by a deficient activity of the lacrimal functional unit. In addition, it is associated with systemic autoimmune diseases such as Sjögren´s Syndrome, rheumatoid arthritis, systemic lupus erythematosus and some drug administration. The treatment of dry eye disease is based on the typical signs and symptoms of dry eye, which are associated with hyperosmolarity, ocular surface inflammation, discomfort, visual disturbance, and tear film instability. Areas covered: This review is focused on synthetic drugs currently used in clinical practice, from phase III development onwards to treat the ocular surface signs and symptoms of dry eye disease. Expert opinion: The multifactorial disease and the lack of correlation between signs and symptoms imply that not all the pharmacological approaches will be successful for dry eye. The correct design of the clinical trials, with appropriate endpoints, and the type of dry eye under study are complicated but mandatory. The anti-inflammatory and secretagogues drugs are both the main compounds to currently treat the dry eye disease.

The role and therapeutic potential of melatonin in age-related ocular diseases.

The eye is continuously exposed to solar UV radiation and pollutants, making it prone to oxidative attacks. In fact, oxidative damage is a major cause of age-related ocular diseases including cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy. As the nature of lens cells, trabecular meshwork cells, retinal ganglion cells, retinal pigment epithelial cells, and photoreceptors is postmitotic, autophagy plays a critical role in their cellular homeostasis. In age-related ocular diseases, this process is impaired, and thus, oxidative damage becomes irreversible. Other conditions such as low-grade chronic inflammation and angiogenesis also contribute to the development of retinal diseases (glaucoma, age-related macular degeneration and diabetic retinopathy). As melatonin is known to have remarkable qualities such as antioxidant/antinitridergic, mitochondrial protector, autophagy modulator, anti-inflammatory, and anti-angiogenic, it can represent a powerful tool to counteract all these diseases. The present review analyzes the role and therapeutic potential of melatonin in age-related ocular diseases, focusing on nitro-oxidative stress, autophagy, inflammation, and angiogenesis mechanisms.

An update on dry eye disease molecular treatment: advances in drug pipelines.

INTRODUCTION: Dry eye disease is a common disorder provoking changes in tear film and ocular surface. Untreated dry eye could cause ocular infections, corneal ulcer and blindness. Only a few drugs are authorized so far for the treatment of dry eye disease and the possibilities of evolution in this sector are immense. Consequently, a significant number of new potential solutions are under development or placed in the pharmaceutical pipeline, promising better results and lesser side effects. AREAS COVERED: In this article, the corresponding literature and recent Phase III clinical trial data and the corresponding literature, for dry eye disease treatment are reviewed, revealing the new strategic movements in drug pipelines. EXPERT OPINION: From the clinical trial results, the advancement in tear substitutes and secretagogues in addressing specific deficiencies of tear components even though not resolving the underlying conditions of the disease is evident. The vast majority of new compounds under development are anti-inflammatories, steroids, non-steroids and antibiotics; however, there are also some novel lubricating drops and mucin-tear secretagogues. A future aggressive therapy for dry eye, depending on the severity of the symptoms, would include combinations of soft steroids, anti-inflammatories, such as cyclosporine A, with the addition of the new polyvalent mucin and tear secretagogues.

Fármacos de la enfermedad de ojo seco actualmente en evaluación en ensayos clínicos / Dry eye disease compounds currently under evaluation in clinical trials

El síndrome de ojo seco es un trastorno bastante común, que provoca cambios en la cantidad y la composición de la lágrima, siendo la manifestación oftálmica más común de enfermedades inflamatorias sistémicas. El ojo seco no tratado puede provocar un aumento del riesgo de infección ocular, úlceras corneales y en casos extremos ceguera. Actualmente sólo unos pocos fármacos están autorizados para el tratamiento de la enfermedad y las posibilidades de evolución en este sector son inmensas. La tendencia del futuro está dirigida hacia el desarrollo de fármacos que controlan la inflamación o estimulan la secreción de las mucinas y del componente acuoso de las lágrimas. Un número significativo de nuevos compuestos están en desarrollo o ya están en ensayos clínicos, con aparentes mejores resultados y efectos secundarios menos adversos, pero una vez más dejando desatendidas las principales causas de la enfermedad. En este artículo revisamos la literatura correspondiente, los últimos datos de los ensayos clínicos y las patentes relativas a futuros compuestos farmacéuticos para el tratamiento de la enfermedad del ojo seco, desvelando los nuevos movimientos estratégicos de la industria farmacéutica

Dry eye syndrome is a common disorder provoking changes in tear quantity and composition being the most common ophthalmic manifestation of systemic inflammatory diseases. Untreated dry eye could cause increased risk of ocular infection, corneal ulcer and blindness. Only a few drugs are authorized so far for the treatment of dry eye disease and the possibilities of evolution in this sector are immense. Accordingly, the future tendency is towards the development of drugs to control the inflammation or stimulate the mucin and tear secretion. A significant number of new potential solutions are under development or placed in the pharmaceutical pipeline, promising better results and lesser side effects, but still leaving unattended the main causes of the disease. In this article, we review the corresponding literature, recent clinical trials data and patents concerning future pharmaceutical compounds for dry eye disease treatment, presenting the new strategic movements of the pharmaceutical industry

Recent developments on dry eye disease treatment compounds.

Dry eye syndrome is a common tears and ocular surface multifactorial disease, described by changes in the ocular surface epithelia related to reduced tears quantity and ocular surface sensitivity, leading to inflammatory reaction. Managing the eye inflammation proved helpful to patients with dry eye disease and current treatment is based on the use of topically applied artificial tear products/lubricants, tear retention management, stimulation of tear secretion and using anti-inflammatory drugs. In this article we revise the corresponding literature and patents assembling the new treatment approaches of novel and future pharmaceutical compounds destined for the dry eye disease treatment. The most frequent categories of compounds presented are secretagogues and anti-inflammatory drugs. These compounds are the research outcome of novel therapeutic strategies designed to reduce key inflammatory pathways and restore healthy tear film.

Contact lenses: promising devices for ocular drug delivery.

In the ocular pharmacology market, there is a noteworthy unmet demand for more efficacious delivery of ocular therapeutics. Contact lenses are emerging as an alternative ophthalmic drug delivery system to resolve the drawbacks of the conventional topical application methods. Thus, contact lenses drug delivery systems have been developed to provide an increased residence time of the drug at the surface of the eye leading to enhanced bioavailability and more convenient and efficacious therapy. Several research groups have already explored the feasibility and potential of contact lenses loading conventional drugs used to treat anterior eye disorders. Drug incorporation to the lens body is achieved with techniques, like simple soaking, inclusion of drug-loaded colloidal nanoparticles, or molecular imprinting. Regardless of the technique used, key properties of the contact lens, such as transparency and oxygen permeability, should be preserved. In this article, we reviewed the different techniques used for drug delivery through contact lenses, analyzing their advantages and disadvantages, and focused on articles describing contact lens-based ophthalmic drug delivery systems with significant potential to use in ocular therapeutics.

Ocular disorders and the utility of animal models in the discovery of melatoninergic drugs with therapeutic potential.

INTRODUCTION: The pineal indole-derived hormone melatonin is a modulator of circadian and seasonal rhythms with an important role in ocular health and disease. This could be due to specific melatonin receptors that have been identified in structures such as cornea, lens, ciliary body, retina, choroid and sclera. In addition, a local synthesis of melatonin occurs in several of these ocular tissues. AREAS COVERED: The authors review existing literature on the most common animal models where ocular melatonin actions have been tested. The therapeutic potential of melatonin in diabetic keratopathy and retinopathy, keratitis, cataracts, glaucoma, uveitis, age-related macular degeneration and retinitis pigmentosa is discussed. Furthermore, the authors comment on the usefulness of different animal models for the development of melatoninergic drugs with therapeutic potential. EXPERT OPINION: The use of animals for the study of ocular diseases and the potentiality of melatonin and its analogs, as future therapeutic drugs, should be performed on the basis of a rationale study. It is important to note that melatonin receptors seem to be widespread all over the eye. This strongly suggests that, in order to modify the physiology and biochemistry of malfunctioning ocular tissue, the melatonin receptors which are present in that tissue must be first identified. Second there is the need to confirm that those receptors targeted perform the desirable responses, and as a third measure, to use selective agonists (or antagonists) instead of melatonin. However, although some animals mimic ocular pathologies relatively well, and these can be used in melatonin studies, there is still a long way to go till some of the results obtained in animal models could be used for human therapy.

Recent patents and developments in glaucoma biomarkers.

Glaucoma is an eye condition mainly developed from an excessive intraocular pressure. The condition tends to be inherited and may not show up until later in life. The increased pressure, can damage the optic nerve, provoking loss of vision. Without treatment, glaucoma can cause blindness within a few years; consequently glaucoma has to be diagnosed before long-term visual loss occurs. If it is diagnosed and treated early, the disease can be controlled. Usually, the patient does not notice any early symptoms or pain from this increased pressure, so the early diagnosis is problematic. Over half of the patients with glaucoma are unaware they have this blinding disease and by the time they are diagnosed, they already have irreversibly lost approximately 30-50% of their retinal ganglion cells. Glaucoma diagnosis is currently based on specific signs of the disease, characteristic optic nerve head changes and visual field loss. Thus, improved methods for early diagnosis of glaucoma are needed. Molecular genetics are valuable for the understanding the pathophysiology and cure of glaucoma, but still are not widely used for its diagnosis. Genetic studies on glaucoma have revealed many genes and chromosomal loci associated to glaucoma. Consequently, a better understanding of the molecular mechanisms underlying glaucoma is required to obtain early diagnosis and avoid potential disease progression. In this article, we revise the patents and the corresponding literature on the latest developments and approaches in glaucoma diagnosis, using mainly molecular genetics.

Potential role of Rho-associated protein kinase inhibitors for glaucoma treatment.

Rho kinase inhibitors are widely considered as a new treatment for glaucoma. Rho kinase inhibition has been shown in vitro and in vivo to lower intraocular pressure. Furthermore in the first clinical reports involving healthy human subjects, the results were quite promising. The potential of this new class of medicines is enormous in a field where there were not many developments lately. The inhibition of Rho kinase lowers the intraocular pressure by increasing the outflow through the trabecular meshwork. Increased blood flow to the optic nerve and a possible delay of optic nerve cell death has also been reported. As a consequence, the exploration of pharmacological inhibitors of Rho kinase signaling is actively being pursued by a number of pharmaceutical companies such as Senju Pharmaceuticals, Novartis, Kowa, Santen, Aerie, Inspire and others. In this article, we review the latest patents in this field, with their corresponding literature, regarding Rho kinase inhibitors for the treatment of intraocular pressure and summarize the many roles of Rho kinase signaling in the eye.