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Der Ophthalmologe : Zeitschrift Der... Jul 2015
Topics: Aging; Animals; Humans; Retinal Diseases; Vitreous Body
PubMed: 26065526
DOI: 10.1007/s00347-015-0060-4 -
Modern Problems in Ophthalmology 1976The vitreous is feebly antigenic and is characterized by the absence of gamma-globulins and immunocompetent cells. Moreover, it is isolated from the aqueous humour by a... (Review)
Review
The vitreous is feebly antigenic and is characterized by the absence of gamma-globulins and immunocompetent cells. Moreover, it is isolated from the aqueous humour by a mucopolysaccharide molecular filter. It represents an incomplete and primitive immunological system, reacting like an embryonic tissue and exhibiting only phagocytosis.
Topics: Animals; Antigens; Humans; Immunoglobulins; Phagocytosis; Transplantation Immunology; Transplantation, Heterologous; Transplantation, Homologous; Vitreous Body
PubMed: 765783
DOI: No ID Found -
Annals of Biomedical Engineering Oct 2016Although linked to several vitreoretinal pathologies including traumatic retinal tears, breaks, and symptomatic vitreomacular traction, the dynamic material behavior of...
Although linked to several vitreoretinal pathologies including traumatic retinal tears, breaks, and symptomatic vitreomacular traction, the dynamic material behavior of the vitreous body in response to mechanical loads is not well understood. The purpose of this study was to evaluate spatiotemporal patterns of collagen fiber reorganization and vitreous deformation (strain) in response to tensile and compressive forces. Using thick slabs of bovine eyes we examined collagen fiber reorganization following tensile and compressive step-loading with quantitative polarized light imaging. Strains were measured from sparse marker arrays and temporal collagen behavior was estimated from creep compliance rheological tests. Results showed that under applied loads (1) collagen fibers became significantly more aligned at the vitreous base (near the pars plana and the ciliary body), (2) vitreous located directly behind the lens deformed significantly more than surrounding regions, and (3) changes in collagen fiber alignment occurred on a short (<5 s) timescale. Together these results show that, despite a homogeneous visual appearance, the vitreous body exhibits anisotropic material behavior in tension and compression. Spatiotemporal patterns of collagen rearrangement were consistent with epidemiological patterns of traumatic retinal damage and vitreoretinal topology. High strains in the vitreous corresponded with locations of lower collagen content that are prone to age-related degeneration. These data suggest that differential fiber alignment and mechanical deformation could contribute to the pathogenesis of these diseases. Computational models that incorporate these experimental data will help improve our understanding of the biomechanical mechanisms that contribute to the pathogenesis of traumatic retinal damage, vitreous degeneration, and vitreoretinal disease.
Topics: Animals; Anisotropy; Cattle; Eye Diseases; Humans; Intraocular Pressure; Lens, Crystalline; Stress, Mechanical; Vitreous Body
PubMed: 26983839
DOI: 10.1007/s10439-016-1589-3 -
Science Advances Nov 2018The intravitreal delivery of therapeutic agents promises major benefits in the field of ocular medicine. Traditional delivery methods rely on the random, passive...
The intravitreal delivery of therapeutic agents promises major benefits in the field of ocular medicine. Traditional delivery methods rely on the random, passive diffusion of molecules, which do not allow for the rapid delivery of a concentrated cargo to a defined region at the posterior pole of the eye. The use of particles promises targeted delivery but faces the challenge that most tissues including the vitreous have a tight macromolecular matrix that acts as a barrier and prevents its penetration. Here, we demonstrate novel intravitreal delivery microvehicles-slippery micropropellers-that can be actively propelled through the vitreous humor to reach the retina. The propulsion is achieved by helical magnetic micropropellers that have a liquid layer coating to minimize adhesion to the surrounding biopolymeric network. The submicrometer diameter of the propellers enables the penetration of the biopolymeric network and the propulsion through the porcine vitreous body of the eye over centimeter distances. Clinical optical coherence tomography is used to monitor the movement of the propellers and confirm their arrival on the retina near the optic disc. Overcoming the adhesion forces and actively navigating a swarm of micropropellers in the dense vitreous humor promise practical applications in ophthalmology.
Topics: Animals; Biomechanical Phenomena; Fluorocarbons; Intravitreal Injections; Pharmaceutical Preparations; Retina; Swine; Vitreous Body
PubMed: 30406201
DOI: 10.1126/sciadv.aat4388 -
British Medical Journal May 1973
Topics: Air; Humans; Hyaluronic Acid; Methods; Retina; Silicones; Transplantation, Homologous; Vitreous Body
PubMed: 4704492
DOI: No ID Found -
Current Eye Research Apr 2021Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the... (Review)
Review
Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested , has been hypothesized to be different . Future studies should focus on testing the mechanical properties of the vitreous or . In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport.
Topics: Biocompatible Materials; Biological Transport; Biomechanical Phenomena; Biomimetic Materials; Humans; Hydrogels; Viscoelastic Substances; Vitreous Body
PubMed: 33040616
DOI: 10.1080/02713683.2020.1826977 -
Ophthalmic Research 1987Fibrinogen was injected in the vitreous cavity of 29 rabbits with follow-up for 75 days. Vitreous membrane formation was detected by indirect ophthalmoscopy and...
Fibrinogen was injected in the vitreous cavity of 29 rabbits with follow-up for 75 days. Vitreous membrane formation was detected by indirect ophthalmoscopy and confirmed by histopathological study. Membrane formation was significantly more common in the fibrinogen group than in the control group. Fifteen days after injection, the membranes decreased in size and gave place to vitreous liquefaction in the majority of eyes in the fibrinogen group. Histochemical stains for fibrinogen were positive in half of the vitreous membranes. Fibrinogen is thought to be transformed into a long fibrin polymer forming a matrix for surrounding cells to proliferate in the vitreous. An effective fibrinolytic system in the vitreous explains the ultimate resolution of most of the fibrinogen-induced membranes. Simple fibrinogen injections do not provide a good model for long-term vitreous band formation, yet they add more evidence to the role of fibrin in the pathogenesis of vitreoproliferative diseases. The spontaneous resolution of some proliferative vitreoretinopathies parallels the reversibility of most of the fibrinogen-induced vitreous membranes.
Topics: Animals; Fibrinogen; Injections; Membranes; Rabbits; Time Factors; Vitreous Body
PubMed: 3658327
DOI: 10.1159/000265489 -
Archives of Ophthalmology (Chicago,... Oct 1974
Review
Topics: Adolescent; Adult; Amphotericin B; Animals; Cataract Extraction; Child; Child, Preschool; Electrocoagulation; Eye Diseases; Eye Foreign Bodies; Female; Hemorrhage; Humans; Infant, Newborn; Male; Methicillin; Methods; Middle Aged; Postoperative Complications; Prostheses and Implants; Rabbits; Retina; Retinal Detachment; Retinal Diseases; Urokinase-Type Plasminogen Activator; Uvea; Vitreous Body
PubMed: 4607273
DOI: 10.1001/archopht.1974.01010010360022 -
Archives of Ophthalmology (Chicago,... Jul 1973
Review
Topics: Adult; Animals; Blood Coagulation; Electroretinography; Eye Diseases; Eye Foreign Bodies; Female; Hemorrhage; Humans; Hyaluronic Acid; Intracranial Aneurysm; Male; Postoperative Complications; Rabbits; Ultrasonography; Vitreous Body
PubMed: 4577008
DOI: 10.1001/archopht.1973.01000050071016 -
Archives of Ophthalmology (Chicago,... May 1972
Review
Topics: Animals; Eye Diseases; Hemorrhage; Humans; Middle Aged; Organ Size; Rabbits; Retinopathy of Prematurity; Vitreous Body; Water-Electrolyte Balance
PubMed: 4554948
DOI: 10.1001/archopht.1972.01000020601025