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Topic Review
Nitrosative Stress in Retinal Pathologies
Nitric oxide (NO) is a gas molecule with diverse physiological and cellular functions. In the eye, NO is used to maintain normal visual function as it is involved in photoreceptor light transduction. In addition, NO acts as a rapid vascular endothelial relaxant, is involved in the control of retinal blood flow under basal conditions and mediates the vasodilator responses of different substances such as acetylcholine, bradykinin, histamine, substance P or insulin. However, the retina is rich in polyunsaturated lipid membranes and is sensitive to the action of reactive oxygen and nitrogen species. Products generated from NO (i.e., dinitrogen trioxide (N2O3) and peroxynitrite) have great oxidative damaging effects. Oxygen and nitrogen species can react with biomolecules (lipids, proteins and DNA), potentially leading to cell death, and this is particularly important in the retina.
  • 737
  • 22 Sep 2021
Topic Review
Natural Antioxidant Activities of Plants in Preventing Cataractogenesis
A cataract is a condition where the eye’s lens clouds and can lead to progressive loss of vision. The formation of cataracts is linked to both the production of reactive oxygen species (ROS) and the reduction of endogenous antioxidants. Numerous studies have demonstrated that plants contain numerous antioxidant compounds that can be used as cataract preventatives or inhibitors. 
  • 729
  • 02 Aug 2022
Topic Review
Acanthamoeba Keratitis
AK is relatively rare among corneal infections, with an estimated prevalence of 1–9 cases per 100,000. However, in Western countries, the incidence of AK has been steadily rising in direct correlation with contact lens wearing, which is the predominant risk factor.
  • 725
  • 29 Mar 2021
Topic Review
Posterior Capsule Opacification
Posterior capsule opacification (PCO) is the most common complication arising from the corrective surgery used to treat cataract patients. PCO arises when lens epithelial cells (LEC) residing in the capsular bag post-surgery undergo hyper-proliferation and transdifferentiation into myofibroblasts, migrating from the posterior capsule over the visual axis of the newly implanted intraocular lens (IOL). The developmental pathways underlying PCO are yet to be fully understood and the current literature is contradictory regarding the impact of the recognised risk factors of PCO. The aim of this review is firstly to collate the known biochemical pathways that lead to PCO development, providing an up-to-date chronological overview from surgery to established PCO formation. Secondly, the risk factors of PCO are evaluated, focussing on the impact of IOLs’ properties. Finally, the latest experimental model designs used in PCO research are discussed to demonstrate the ongoing development of clinical PCO models, the efficacy of newly developed IOL technology, and potential therapeutic interventions. This review will contribute to current PCO literature by presenting an updated overview of the known developmental pathways of PCO, an evaluation of the impact of the risk factors underlying its development, and the latest experimental models used to investigate PCO. Furthermore, the review should provide developmental routes for research into the investigation of potential therapeutic interventions and improvements in IOL design in the aid of preventing PCO for new and existing patients.
  • 722
  • 11 Oct 2021
Topic Review
Role of Retinal Pigment Epithelium
The retinal pigment epithelium (RPE), situated upon Bruch’s membrane, plays multiple roles in the ocular system by interacting with photoreceptors and. Therefore, dysfunction of the RPE causes diseases related to vision loss, such as age-related macular degeneration (AMD). 
  • 719
  • 24 Nov 2021
Topic Review
Role of Neutrophils on the Ocular Surface
Neutrophils are considered short-term and terminally differentiated phagocytes with no significant gene expression or regulatory role in adaptive immunity. However, in recent years, opinions on the role of neutrophils have been developing. Neutrophils are primarily short-term polymorphonuclear cells (PMNs) related with the first line combatant to pathogens, which can phagocytose potentially harmful antigens and trigger strong antimicrobial defenses, including the release of reactive oxygen species (ROS) such as superoxide and neutrophil extracellular traps.
  • 719
  • 11 Oct 2021
Topic Review
Tear Hyperosmolarity and Dry Eye Disease
Dry eye disease (DED) is a multifactorial disorder of the lacrimal system and ocular surface, characterized by a deficiency in the quality and/or quantity of the tear fluid. The multifactorial nature of DED encompasses a number of interconnected underlying pathologies, including loss of homeostasis, instability and hyperosmolarity of the tears, and the induction and propagation of detrimental inflammatory responses in the eyes, which finally results in the development of neurosensory dysfunction and visual disruption.
  • 715
  • 12 Dec 2023
Topic Review
Thyroid Eye Disease
Thyroid eye disease (TED) is an inflammatory disease of orbital tissue characterized by infiltration of lymphocytic cells, orbital fat expansion, and extraocular muscle swelling. The gravity of thyroid eye disease lies in its sight-threatening, debilitating, and disfiguring potential. Despite extensive ongoing research about TED, the disorder remains elusive in its exact pathophysiology, prevention, and ideal treatment.
  • 709
  • 22 Dec 2022
Topic Review
Gene Therapy Approaches to Treat Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a group of hereditary diseases that result in the progressive degeneration of the retina's photoreceptor cells, primarily starting with the rods. This gradual loss of vision is the most common form of inherited retinal dystrophy, and it imposes a significant burden on both individuals and society. RP is a leading cause of visual disability and blindness in people under 60, affecting more than 1.5 million individuals worldwide. The most common symptoms of RP include nyctalopia and gradual peripheral vision loss, which may ultimately lead to complete blindness.
  • 704
  • 06 Jun 2023
Topic Review
Nano-based DDS for Posterior Segment Diseases
The complex anatomy of the eye presents a major challenge in the treatment of posterior segment eye diseases, hindering the effective delivery of medications. Conventional treatments, including topical eye drops and intravitreal injections, are limited by poor bioavailability and short residence time, necessitating frequent dosing to manage the disease. Intravitreal injections can also lead to serious ocular complications. Biodegradable nano-based drug delivery systems (DDSs) have emerged as a potential solution to these limitations, offering longer residence time in ocular tissues and better penetration through ocular barriers. Furthermore, the biodegradable polymers used to create these systems are nanosized, reducing the risk of toxicity and adverse reactions.
  • 701
  • 12 May 2023
Topic Review
Treatment of Amblyopia
Amblyopia is the most common cause of monocular poor vision affecting up to 3.7% of the global population. Classically, the first step in treatment has been optical correction, followed by patching and/or pharmacological treatment. However, this is an evolving scenario, since researchers and clinicians are interested in new binocular treatments due to the increasing development of new technologies. In this article main, current binocular treatments as Dig Rush, falling blocks, I-BiT, Occlu-tab, Vivid Vision, and movies are reviewed for binocular amblyopia management. 
  • 696
  • 05 Jul 2021
Topic Review
Energy Metabolism and Glaucoma
Glaucoma, the leading cause of irreversible blindness, is a heterogeneous group of diseases characterized by progressive loss of retinal ganglion cells (RGCs) and their axons and leads to visual loss and blindness. Risk factors for the onset and progression of glaucoma include systemic and ocular factors such as older age, lower ocular perfusion pressure, and intraocular pressure (IOP). Early signs of RGC damage comprise impairment of axonal transport, downregulation of specific genes and metabolic changes. The brain is often cited to be the highest energy-demanding tissue of the human body. The retina is estimated to have equally high demands. RGCs are particularly active in metabolism and vulnerable to energy insufficiency. Understanding the energy metabolism of the inner retina, especially of the RGCs, is pivotal for understanding glaucoma’s pathophysiology.
  • 691
  • 22 Apr 2021
Topic Review
Treatment for Central Serous Chorioretinopathy
Central serous chorioretinopathy (CSC) is a controversial disease both in terms of clinical classification and choice of therapeutic strategy. Choroidal layers, retinal pigment epithelium (RPE), photoreceptors, and retina are involved to varying degrees. 
  • 688
  • 18 Mar 2021
Topic Review
Biomedical Applications of Lactoferrin on the Ocular Surface
Lactoferrin (LF) is a first-line defense protein with a pleiotropic functional pattern that includes anti-inflammatory, immunomodulatory, antiviral, antibacterial, and antitumoral properties. Remarkably, this iron-binding glycoprotein promotes iron retention, restricting free radical production and avoiding oxidative damage and inflammation. On the ocular surface, LF is released from corneal epithelial cells and lacrimal glands, representing a significant percentage of the total tear fluid proteins. Due to its multifunctionality, the availability of LF may be limited in several ocular disorders. Consequently, to reinforce the action of this highly beneficial glycoprotein on the ocular surface, LF has been proposed for the treatment of different conditions such as dry eye, keratoconus, conjunctivitis, and viral or bacterial ocular infections, among others.
  • 688
  • 15 Mar 2023
Topic Review
Ocular Medication Routes of Administration
Ocular drug administration encompasses a range of routes, each with its own advantages and limitations. The available methods include systemic delivery (such as oral, intravenous, and subcutaneous routes) as well as local delivery options (including topical eye drops, periocular or intravitreal injections, and intravitreal implants). While these approaches can be effective in delivering medications to the eye, they also have inherent drawbacks, which will be explored in greater detail in this entry. Notably, understanding the strengths and limitations of these ocular drug administration routes is crucial for optimizing therapy and achieving the desired therapeutic outcomes while minimizing potential adverse effects.   
  • 687
  • 04 Dec 2023
Topic Review
Advanced Drug Delivery for Treating Sjögren’s Dry Eye
Sjögren’s syndrome is a chronic and insidious autoimmune disease characterized by lymphocyte infiltration of exocrine glands. Patients typically present with dry eye (keratoconjunctivitis sicca), dry mouth (xerostomia), and other systemic manifestations. The current management for Sjögren's syndrome dry eye (SSDE) has been ineffective as it only targets ocular surface inflammation and dryness without addressing the specific disease process. Ophthalmologists often adopt a trial-and-error approach, which allows the cycle of dry eye disease (DED) to progress and potentially cause permanent damage to the lacrimal functional unit. Topical treatments also depend on patients' ability to administer eye drops and their compliance. These limitations emphasize the need for personalized, targeted treatments that address the underlying pathophysiology of SSDE. This article aims to present new advances in ocular drug delivery for more effective treatment.
  • 683
  • 10 Feb 2023
Topic Review
Diabetic Retinopathy Treatment
Diabetic retinopathy (DR) is one of the leading matters of vision-loss globally. Even though there have been extensive efforts to reduce vision loss, the prevalence of DR is still uprising. There are several pharmacological and surgical therapies currently used in clinics, but none of them has not been used as effective therapies at the early stage of DR.
  • 680
  • 01 Nov 2021
Topic Review
Dietary Antioxidants in Age-Related Macular Degeneration and Glaucoma
Age-related macular degeneration (AMD) and glaucoma are ophthalmic neurodegenerative diseases responsible for irreversible vision loss in the world population. Only a few therapies can be used to slow down the progression of these diseases and there are no available treatment strategies for reversing the degeneration of the neural retina. In AMD, the pathological process causes the malfunction and damage of the retinal pigmented epithelium and photoreceptors in the macula. In glaucoma, damage of the retinal ganglion cells and their axons is observed and treatment strategies are limited to intraocular pressure lowering. Therefore, other prophylactic and/or therapeutic methods are needed. Oxidative stress is involved in the neurodegenerative process accompanying both AMD and glaucoma; therefore, the use of antioxidant agents would clearly be beneficial, which is supported by the decreased prevalence and progression of AMD in patients adherent to a diet naturally rich in antioxidants.
  • 671
  • 11 Nov 2021
Topic Review
Ocular Surface Squamous Neoplasia
Ocular surface squamous neoplasia (OSSN) encompasses a broad spectrum of neoplastic changes involving the squamous epithelium of the conjunctiva, cornea and limbus ranging from mild dysplasia, intraepithelial neoplasia (carcinoma in situ) to squamous cell carcinoma (SCC).
  • 663
  • 11 Jan 2023
Topic Review
Oxidative Stress in Retinal Dystrophies
Retinal cell survival requires an equilibrium between oxygen, reactive oxygen species, and antioxidant molecules that counteract oxidative stress damage. Oxidative stress alters cell homeostasis and elicits a protective cell response, which is most relevant in photoreceptors and retinal ganglion cells, neurons with a high metabolic rate that are continuously subject to light/oxidative stress insults. Any alteration on the retinal cell mechanisms to respond to oxidative stress injuries results in cell damage and apoptosis. Therefore, antioxidants agents, modulators of gene expression and inducers of cytoprotective signaling pathways may be used as potential therapies to ameliorate phenotypic symptoms in multifactorial and rare retinal dystrophies associated to oxidative stress injuries.
  • 658
  • 22 Sep 2021
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