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Corneal Opacification
Corneal opacification is a term used when the human cornea loses its transparency. The term corneal opacity is used particularly for the loss of transparency of cornea due to scarring. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The term corneal blindness is commonly used to describe blindness due to corneal opacity. Keratoplasty also known as corneal transplantation is the main treatment option for visual improvement in corneal opacity. Other treatments which may improve visual outcome includes optical iridectomy, phototherapeutic keratectomy and keratoprosthesises. Corneal tattooing may be used for improving the cosmetic appearance of the opaque eye. Types Depending on the density, corneal op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmology
Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. In the United States, following graduation from medical school, one must complete a four-year residency in ophthalmology to become an ophthalmologist. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat ailments, such as eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care—medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Scattering
In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called '' diffuse reflections'' and unscattered reflections are called '' specular'' (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as far as Isaac Newton in the 17th century). As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" (not then recognized as electromagnetic in nature) in 1800. John Tyndall, a pioneer in light scattering research, noted the con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sclerocornea
Sclerocornea is an extremely rare Birth defect, congenital anomaly of the human eye, eye, it is considered a form of Corneal opacity, congenital corneal opacity (CCO) with no clear gender bias, in which the cornea blends with sclera, having no Corneal limbus, clear-cut boundary. The extent of the resulting opacity varies from peripheral to total (''sclerocornea totalis''). While the exact historical origins of its documentation are unclear, studies on sclerocornea has long been recognized in ophthalmology as a rare but significant anomaly going as far back as the 1960's. The severe form is thought to be inherited in an autosomal recessive manner, but there may be another, milder form that is expressed in a dominant fashion. In some cases the patients also have abnormalities beyond the eye (Systemic disease, systemic), such as limb deformities and craniofacial and genitourinary defects. According to one tissue analysis performed after corneal transplantation, the sulfation pattern of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Dystrophy-perceptive Deafness Syndrome
Corneal dystrophy-perceptive deafness syndrome, also known as Harboyan syndrome, is a rare genetic disorder characterized by congenital hereditary corneal dystrophy that occurs alongside progressive hearing loss of post-lingual onset. Signs and symptoms Below is a list of the symptoms people with this condition exhibit: * Corneal dystrophy * Clouding of the cornea * Nystagmus * Blurry vision * Generalized vision impairment * Progressive post-lingual hearing loss The latter usually appears between the ages of 20 and 30 years old. Complications The hearing loss and visual impairment associated with this condition can cause difficulties with living. Genetics This condition is caused by mutations in the SLC4A11 gene which are inherited in an autosomal recessive manner (most of the time). Desir et al. (2007) identified mutations in this gene in 6 families, of which 3 were consanguineous and 3 were not, they found homozygosity for the mutation in the consanguineous families a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucous Membrane Pemphigoid
Mucous membrane pemphigoid is a rare chronic autoimmune subepithelial blistering disease characterized by erosive lesions of the mucous membranes and skin. It is one of the pemphigoid diseases that can result in scarring. Signs and symptoms The autoimmune reaction most commonly affects the oral mucosa in the mouth, causing lesions in the gums (gingiva), known as desquamative gingivitis. More severe cases can also affect areas of mucous membrane elsewhere in the body, such as the sinuses, genitals, anus, and cornea. When the cornea of the eye is affected, repeated scarring may result in blindness. ''Brunsting–Perry cicatricial pemphigoid'' is a rare variant of mucous membrane pemphigoid involving the scalp and the neck without mucosal involvement. It is proposed by some authors that this be called a variant of epidermolysis bullosa acquisita. Nikolsky's sign (gentle lateral pressure) on unaffected mucosa or skin raises a bulla. If no lesions are present on examination it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onchocerciasis
Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm ''Onchocerca volvulus''. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindness due to infection, after trachoma. The parasitic worm is spread by the bites of a black fly of the ''Simulium'' genus. Usually, many bites are required before infection occurs. These flies live near rivers, hence the common name of the disease, River blindness. Once inside a person, the worms create larvae that make their way out to the skin, where they can infect the next black fly that bites the person. There are a number of ways to make the diagnosis, including placing a biopsy of the skin in normal saline and watching for the larva to come out, looking in the eye for larvae, and looking within the bumps under the skin for adult worms. A vaccine against the disease does not exist. Prevention is by avoiding being bitten by flies. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachoma
Trachoma is an infectious disease caused by bacterium '' Chlamydia trachomatis''. The infection causes a roughening of the inner surface of the eyelids. This roughening can lead to pain in the eyes, breakdown of the outer surface or cornea of the eyes, and eventual blindness. Untreated, repeated trachoma infections can result in a form of permanent blindness when the eyelids turn inward. The bacteria that cause the disease can be spread by both direct and indirect contact with an affected person's eyes or nose. Indirect contact includes through clothing or flies that have come into contact with an affected person's eyes or nose. Children spread the disease more often than adults. Poor sanitation, crowded living conditions, and insufficient clean water and toilets also increase spread. Efforts to prevent the disease include improving access to clean water and treatment with antibiotics to decrease the number of people infected with the bacterium. This may include treatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin A Deficiency
Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Vitamin A plays a major role in phototransduction, so this deficiency impairs vision, often presenting with nyctalopia (night blindness). In more severe VAD cases, it can progress to xerophthalmia, keratomalacia, and complete blindness. Vitamin A deficiency is the leading cause of preventable childhood blindness worldwide and is a major cause of childhood mortality. Each year, approximately 250,000 to 500,000 malnourished children in the developing world go blind from a VAD, with about half of whom dying within a year of losing their sight. Addressing VAD has been a critical focus of global health initiatives, including Sustainable Development Goal 2: to end hunger, achieve food security and improved nutrition and promote sustainable agriculture. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xerophthalmia
Xerophthalmia (from Ancient Greek () meaning "dry" and () meaning "eye") is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A deficiency, which is sometimes used to describe that condition, although there may be other causes. Xerophthalmia caused by a severe vitamin A deficiency is described by pathologic dryness of the conjunctiva and cornea. The conjunctiva becomes dry, thick and wrinkled. The first symptom is poor vision at night. If untreated, xerophthalmia can lead to dry eye syndrome, corneal ulceration, and ultimately to blindness as a result of corneal and retinal damage. Xerophthalmia usually implies a destructive dryness of the conjunctival epithelium due to dietary vitamin A deficiency—a rare condition in developed countries, but still causing much damage in developing countries. Other forms of dry eye are associated with aging, poor lid closure, scarring from a previous injury, or autoimmune diseases such as rheumat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Ulcer
Corneal ulcer, often resulting from keratitis is an inflammatory or, more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and in farming. In developing countries, children afflicted by vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes persisting throughout life. In ophthalmology, a corneal ulcer usually refers to having an infection, while the term corneal abrasion refers more to a scratch injury. Types Superficial and deep corneal ulcers Corneal ulcers are a common human eye disease. They are caused by trauma, particularly with vegetable matter, as well as chemical injury, contact lenses and infections. Other eye conditions can cause corneal ulcers, such as entropion, distichiasis, corneal dystrophy, and keratoconjunctivitis sicca (dry eye). Many micro-organisms cause infective corneal ulce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Hereditary Endothelial Dystrophy
Congenital hereditary corneal dystrophy (CHED) is a form of corneal endothelial dystrophy that presents at birth. CHED was previously subclassified into two subtypes: CHED1 and CHED2. However in 2015, the International Classification of Corneal Dystrophies (IC3D) renamed the condition "CHED1" to become posterior polymorphous corneal dystrophy, and renamed the condition "CHED2" to become, simply, CHED. Consequently, the scope of this article is restricted to the condition currently referred to as ''CHED'' Signs and symptoms CHED presents congenitally, but has a stationary course. The cornea exhibits a variable degree of clouding: from a diffuse haze, to a "ground glass" appearance, with occasional focal gray spots. The cornea thickens to between two and three times is normal thickness. Rarely, sub-epithelial band keratopathy and elevated intraocular pressure occur. Patients have blurred vision and nystagmus, however it is rare for the condition to be associated with either epi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peters Anomaly
Anterior segment mesenchymal dysgenesis, or simply anterior segment dysgenesis, is a failure of the normal development of the tissues of the anterior segment of the eye. It leads to anomalies in the structure of the mature anterior segment, associated with an increased risk of glaucoma and corneal opacity. Peters' (frequently misspelled as Peter's) anomaly is a specific type of mesenchymal anterior segment dysgenesis, in which there is central corneal leukoma, adhesions of the iris and cornea and abnormalities of the posterior corneal stroma, Descemet's membrane, corneal endothelium, lens and anterior chamber. Pathophysiology Several gene mutations have been identified underlying these anomalies, with the majority of anterior segment dysgenesis genes encoding transcriptional regulators. In this review, the role of the anterior segment dysgenesis genes '' PITX2'' and '' FOXC1'' is considered in relation to the embryology of the anterior segment, the biochemical function of these p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
