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Ocular Prosthesis
An ocular prosthesis, artificial eye or glass eye is a type of craniofacial prosthesis that replaces an absent natural eye following an enucleation, evisceration, or orbital exenteration. The prosthesis fits over an orbital implant and under the eyelids. Though often referred to as a glass eye, the ocular prosthesis roughly takes the shape of a convex shell and is made of medical grade plastic acrylic. A few ocular prostheses today are made of cryolite glass. A variant of the ocular prosthesis is a very thin hard shell known as a scleral shell which can be worn over a damaged or eviscerated eye. Makers of ocular prosthetics are known as ocularists. An ocular prosthesis does ''not'' provide vision; this would be a visual prosthesis. Someone with an ocular prosthesis is altogether blind on the affected side and has monocular (one sided) vision. History The earliest known evidence of the use of ocular prosthesis is that of a woman found in Shahr-I Sokhta, Iran dating back to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Making Glass Eye (LOC) (15601805189)
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Anophthalmia
Anophthalmia, (Greek: ἀνόφθαλμος, "without eye"), is the medical term for the absence of one or both eyes. Both the globe (human eye) and the ocular tissue are missing from the orbit. The absence of the eye will cause a small bony orbit, a constricted mucosal socket, short eyelids, reduced palpebral fissure and malar prominence. Genetic mutations, chromosomal abnormalities, and prenatal environment can all cause anophthalmia. Anophthalmia is an extremely rare disease and is mostly rooted in genetic abnormalities. It can also be associated with other syndromes. Causes ''SOX2'' The most common genetic cause for anophthalmia is mutated SOX2 gene. Sox2 anophthalmia syndrome is caused by a mutation in the Sox2 gene that does not allow it to produce the Sox2 protein that regulates the activity of other genes by binding to certain regions of DNA. Without this Sox2 protein, the activity of genes that is important for the development of the eye is disrupted. Sox2 anophthalmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microphthalmia
Microphthalmia (Greek: grc, μικρός, mikros, small, label=none, grc, ὀφθαλμός, ophthalmos, eye, label=none, also referred as microphthalmos, is a developmental disorder of the eye in which one (unilateral microphthalmia) or both (bilateral microphthalmia) eyes are abnormally small and have anatomic malformations. Microphthalmia is a distinct condition from anophthalmia and nanophthalmia. Although sometimes referred to as 'simple microphthalmia', nanophthalmia is a condition in which the size of the eye is small but no anatomical alterations are present. Presentation Microphthalmia is a congenital disorder in which the globe of the eye is unusually small and structurally disorganized. While the axis of an adult human eye has an average length of about , a diagnosis of microphthalmia generally corresponds to an axial length below in adults. Additionally, the diameter of the cornea is about in affected newborns and in adults with the condition. The presence of a sm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenon's Capsule
Tenon's capsule (), also known as the Tenon capsule, fascial sheath of the eyeball () or the fascia bulbi, is a thin membrane which envelops the eyeball from the optic nerve to the corneal limbus, separating it from the orbital fat and forming a socket in which it moves. The inner surface of Tenon's capsule is smooth and is separated from the outer surface of the sclera by the periscleral lymph space. This lymph space is continuous with the subdural and subarachnoid cavities and is traversed by delicate bands of connective tissue which extend between the capsule and the sclera. The capsule is perforated behind by the ciliary vessels and nerves and fuses with the sheath of the optic nerve and with the sclera around the entrance of the optic nerve. In front it adheres to the conjunctiva, and both structures are attached to the ciliary region of the eyeball. The structure was named after Jacques-René Tenon (1724–1816), a French surgeon and pathologist. Structure Relations Te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vicryl
Vicryl (polyglactin 910) is an absorbable, synthetic, usually braided suture, manufactured by Ethicon Inc., a subsidiary of Johnson and Johnson. A monofilament version is also made for use in ophthalmic practice. It is indicated for soft tissue approximation and ligation. The suture holds its tensile strength for approximately two to three weeks in tissue and is completely absorbed by acid hydrolysis within 56 to 70 days. Vicryl and other polyglycolic-acid sutures may also be treated for more rapid breakdown (" Vicryl Rapide") in rapidly healing tissues such as mucous membrane or impregnated with triclosan (" Vicryl Plus Antibacterial") to provide antimicrobial protection of the suture line. Because Vicryl is slow-absorbing and often braided, its use is contraindicated in the closure of any cutaneous wound exposed to the air, as it draws moisture from the healing tissue to the skin and allows bacteria and irritants to migrate into the wound. This may lead to high reactivity to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylene Terephthalate
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins. In 2016, annual production of PET was 56 million tons. The biggest application is in fibres (in excess of 60%), with bottle production accounting for about 30% of global demand. In the context of textile applications, PET is referred to by its common name, polyester, whereas the acronym ''PET'' is generally used in relation to packaging. Polyester makes up about 18% of world polymer production and is the fourth-most-produced polymer after polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC). PET consists of repeating (C10H8O4) units. PET is commonly recycled, and has the digit 1 (♳) as its resin identification code (RIC). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylene
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including bottles, etc.). , over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market. Many kinds of polyethylene are known, with most having the chemical formula (C2H4)''n''. PE is usually a mixture of similar polymers of ethylene, with various values of ''n''. It can be ''low-density'' or ''high-density'': low-density polyethylene is extruded using high pressure () and high temperature (), while high-density polyethylene is extruded using low pressure () and low temperature (). Polyethylene is usually thermoplastic, but it can be modified to become thermosetting instead, for example, in cross-linked polyethylene. History Polyethylene was first synthesized by the German chemist Hans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxyapatite
Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. Hydroxyapatite is the hydroxyl endmember of the complex apatite group. The OH− ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxyapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis. Up to 50% by volume and 70% by weight of human bone is a modified form of hydroxyapatite, known as bone mineral. Carbonated calcium-deficient hydroxyapatite is the main mineral of which dental enamel and dentin are composed. Hydroxyapatite crystals are also found in pathological calcifications such as those found in breast tumors, as w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(methyl Methacrylate)
Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics. It is a transparent thermoplastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Plexiglas, Acrylite, Astariglas, Lucite, Perclax, and Perspex, among several others ( see below). This plastic is often used in sheet form as a lightweight or shatter-resistant alternative to glass. It can also be used as a casting resin, in inks and coatings, and for many other purposes. Although not a type of familiar silica-based glass, the substance, like many thermoplastics, is often technically classified as a type of glass, in that it is a non-crystalline vitreous substance—hence its occasional historic designation as ''acrylic glass''. Chemically, it is the synthetic polymer of methyl methacrylate. It was developed in 1928 in several different laboratories by many chemists, such as William Chalmers, Otto Röhm, and Walter Bauer, and first brought ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraocular Muscles
The extraocular muscles (extrinsic ocular muscles), are the seven extrinsic muscles of the human eye. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye and the other muscle, the levator palpebrae superioris, controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction. Structure Since only a small part of the eye called the fovea provides sharp vision, the eye must move to follow a target. Eye movements must be precise and fast. This is seen in scenarios like reading, where the reader must shift gaze constantly. Although under voluntary control, most eye movement is accomplished without conscious effort. Precisely how the integration between voluntary and involuntary control of the eye occurs is a subject of continuing research."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ulti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
