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Topic Review
Corneal Infection Models: Bacterial Keratitis
Corneal infection models are tools which can be used to study host-pathogen interactions at the corneal surface. They are highly valuable in the study of bacterial keratitis, a potentially sight-threatening eye infection, localised to the cornea. During bacterial keratitis, bacteria colonise the cornea as biofilm populations which demonstrate an increased resistance to antibiotics and the host immune response. Therefore the presence or absence of biofilm is an important consideration in model development. Corneal infection models include: in vitro models (which use cell culture techniques to generate 3D corneal constructs), ex vivo models (which use whole, excised corneas) and in vivo models (which use live animals).
  • 990
  • 16 Dec 2020
Topic Review
Drug Delivery to Posterior Segment of Eye
The posterior segment of the eye comprises the back two-thirds of the eye, including the vitreous humor, the retina, the choroid and the optic nerve. Posterior Segment Eye Diseases (PSEDs) are then defined as the disorders that affect these tissues with the common main outcome of varying degrees of visual impartment and blindness. The most prevalent diseases are glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. 
  • 967
  • 06 Apr 2022
Topic Review
Chitosan and its Derivatives
Chitosan (CS) is a hemi-synthetic cationic linear polysaccharide produced by the deacetylation of chitin. CS is non-toxic, highly biocompatible, and biodegradable, and it has a low immunogenicity. Additionally, CS has inherent antibacterial properties and a mucoadhesive character and can disrupt epithelial tight junctions, thus acting as a permeability enhancer. As such, CS and its derivatives are well-suited for the challenging field of ocular drug delivery. In the present review article, we will discuss the properties of CS that contribute to its successful application in ocular delivery before reviewing the latest advances in the use of CS for the development of novel ophthalmic delivery systems. Colloidal nanocarriers (nanoparticles, micelles, liposomes) will be presented, followed by CS gels and lenses and ocular inserts. Finally, instances of CS coatings, aiming at conferring mucoadhesiveness to other matrixes, will be presented.
  • 967
  • 31 Jul 2020
Topic Review
Nutrients for Eye-Related Diseases
The risk of macular degeneration can be reduced through the consumption of antioxidant-rich foods, supplements, and nutraceutical formulas. This study focuses on the antioxidants, vitamins, and minerals that have been reported for reducing the risk of macular degeneration and other eye-related diseases. Antioxidants including anthocyanins, carotenoids, flavonoids, and vitamins have been shown to reduce the risk of eye-related diseases. Anthocyanins extracted from berries are powerful antioxidants. Cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin are anthocyanin aglycones detected in berries, currants, and other colored fruits and vegetables. β-Carotene, as well as xanthophyll lutein and zeaxanthin, have been reported to reduce the risk of macular degeneration. Flavonoids from plants help in the prevention of eye-related diseases through anti-inflammatory mechanisms. A combination of these antioxidants, vitamins, and minerals possess a synergistic effect on the prevention or risk reduction of macular degeneration. Formulas have been developed as dietary supplements to cater to the high demand from consumers and patients with eye problems. 
  • 926
  • 15 Sep 2021
Topic Review
Farnsworth-Munsell 100 Hue Test
The Farnsworth-Munsell 100 Hue Color Vision test is a test of the human visual system often used to test for color blindness. The system was developed by Dean Farnsworth in the 1940s and it tests the ability to isolate and arrange minute differences in various color targets with constant value and chroma that cover all the visual hues described by the Munsell color system. There are several variations of the test, one featuring 100 color hues and one featuring 15 color hues. Originally taken in an analog environment with physical hue tiles, the test is now taken from computer consoles. An accurate quantification of color vision accuracy is particularly important to designers, photographers and colorists, who all rely on accurate color vision to produce quality content.
  • 922
  • 01 Dec 2022
Topic Review
Ocular Cystinosis
Cystinosis is a rare autosomal recessive disease that affects about 1 in 100,000–200,000 people among the general population, characterized by high levels of cystine within the lysosomes in cells of certain types of tissues. The accumulation of this substance is caused by mutations in the CTNS gene which codes for cystinosin, the carrier that transports cystine out of the lysosome. The presence of cystine crystals in different tissues leads to the progressive impairment and dysfunction of multiple organs, such as kidneys, pancreas, brain, thyroid and eyes.
  • 914
  • 16 Dec 2020
Topic Review
Dry Eye Disease
Dry eye disease (DED) is a common condition, which usually causes discomfort, but it can also be an origin of ocular pain and visual disturbances. Ocular surface inflammation is thought to be the main factor in the pathogenesis of DED. It has many overlapping causes, such as ocular surgery, environmental triggers, medication use and systemic diseases. Ophthalmic surgery may induce or worsen existing DED symptoms usually for a short-term period .
  • 901
  • 05 May 2021
Topic Review
Antioxidant Defenses in the Eye
This review describes the main antioxidant systems of the human eye, with particular emphasis in those expressed in the natural barriers of antioxidant protection, i.e., the ocular surface, the lens, the retina and its retinal pigment epithelium. In addition to superoxide dismutase, glutathione peroxidase, catalase, peroxiredoxins and selenoproteins, inter alia, metallothioneins (MTs) are considered antioxidant proteins of growing interest with further cell-mediated functions. The state of the art of MTs, including the isoforms classification, the main functions described to date and the zinc-MT redox cycle as antioxidant defense system are comprehensively described.
  • 872
  • 12 Feb 2021
Topic Review
Anterior-Segment Optical-Coherence Tomography
Anterior-segment optical-coherence tomography (AS-OCT) is used to assess the iridocorneal angle and its alterations. The introduction of AS-OCT has led to improved assessments of the anatomy of the iridocorneal-angle and diagnoses of several mechanisms of angle closure which often result in raised intraocular pressure (IOP). Continuous advancements in AS-OCT technology and software, along with an extensive research in the field, have resulted in a wide range of possible parameters that may be used to diagnose and follow up on patients with this spectrum of diseases. However, the clinical relevance of such variables needs to be explored thoroughly.
  • 862
  • 14 Feb 2021
Topic Review
Optical Coherence Tomography (OCT) Findings
The main OCT biomarkers related to progression to advanced AMD include drusen volume, hyperreflective foci (HRF), reticular pseudodrusen or subretinal drusenoid deposits (SDD), incomplete retinal pigment epithelial and outer retinal atrophy (iRORA), hyper-transmission defects, and OCT-reflective drusen substructures (ODS).
  • 858
  • 07 Jan 2022
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