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Metamorphopsia
Metamorphopsia (from , ) is a type of distorted vision in which a grid of straight lines appears wavy and parts of the grid may appear blank. People can first notice they suffer with the condition when looking at mini-blinds in their home. For example, straight lines might be wavy or bendy. Things may appear closer or further than they are. Initially characterized in the 1800s, metamorphopsia was described as one of the primary and most notable indications of myopic and senile maculopathies. Metamorphopsia can present itself as unbalanced vision, resulting from small unintentional movements of the eye as it tries to stabilize the field of vision. Metamorphopsia can also lead to the misrepresentation of an object’s size or shape. It is mainly associated with macular degeneration, particularly age-related macular degeneration with choroidal neovascularization. 80%)—deposition of yellowish extracellular material in and between Bruch's membrane and retinal pigment epithelium (“ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dysmorphopsia
Dysmorphopsia, in a broad sense, is a condition in which a person is unable to correctly perceive objects. It is a visual distortion, used to denote a variant of metamorphopsia in which lines appear wavy. These illusions may be restricted to certain visuals areas, or may affect the entire visual field. It has been associated with meningioma tumors and Occipital lobe, bilateral lateral occipital corital damage, e.g. after carbon monoxide poisoning or drug abuse. Etymology The term ''dysmorphopsia'' comes from the Greek words ''dus'' (bad), ''morphè'' (form) and ''opsis'' (seeing). See also * Hallucination * Macropsia * Metamorphopsia * Micropsia * Occipital lobe * Visual perception References {{reflist Visual disturbances and blindness Neurological disorders Further reading A Dictionary of HallucinationsA neurological disorder presumably underlies painter Francis Bacon distorted world depictionDysmorphopsia: a notable variant of the "thin man" phenomenon? ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amsler Grid - Distorted Vision (metamorphopsia)
Amsler is a surname. Notable people with the surname include: *Marc Amsler (1891–1968), Swiss ophthalmologist **Amsler grid **Amsler sign, a medical sign * Margaret Harris Amsler (1908–2002), American lawyer and academic *Marty Amsler (born 1942), American football player * Samuel Amsler (1791–1849), Swiss engraver See also * Jakob Amsler-Laffon (1823–1912), Swiss mathematician, physicist and engineer *Amsler Island Amsler Island is a small island off the south coast of Anvers Island in the Palmer Archipelago of Antarctica. It sits between Loudwater Cove and Arthur Harbour. The island is a roughly triangular rocky plot of granite land approximately long ..., an island of the Palmer Archipelago, Antarctica {{surname German-language surnames ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Vitreous Detachment
A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous membrane separates from the retina. It refers to the separation of the posterior hyaloid membrane from the retina anywhere posterior to the vitreous base (a 3–4 mm wide attachment to the ora serrata). The condition is common for older adults; over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is not rare for those individuals. Some research has found that the condition is more common among women. Symptoms When this occurs there is a characteristic pattern of symptoms: * Flashes of light (photopsia) * A sudden dramatic increase in the number of floaters * A ring of floaters or hairs just to the temporal side of the central vision As a posterior vitreous detachment proceeds, adherent vitreous membrane may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choroidal Neovascularization
Choroidal neovascularization (CNV) is the creation of new blood vessels in the choroid layer of the eye. Choroidal neovascularization is a common cause of neovascular degenerative maculopathy (i.e. 'wet' macular degeneration) commonly exacerbated by extreme myopia, malignant myopic degeneration, or age-related developments. Causes CNV can occur rapidly in individuals with defects in Bruch's membrane, the innermost layer of the choroid. It is also associated with excessive amounts of vascular endothelial growth factor (VEGF). As well as in wet macular degeneration, CNV can also occur frequently with the rare genetic disease pseudoxanthoma elasticum and rarely with the more common optic disc drusen. CNV has also been associated with extreme myopia or malignant myopic degeneration, where in choroidal neovascularization occurs primarily in the presence of cracks within the retinal (specifically) macular tissue known as lacquer cracks. Symptoms CNV can create a sudden deterioration o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exudate
An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin ''exsūdāre'' 'to (ooze out) sweat' (''ex-'' 'out' and ''sūdāre'' 'to sweat'). Medicine An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can be a pus-like or clear fluid. When an injury occurs, leaving skin exposed, it leaks out of the blood vessels and into nearby tissues. The fluid is composed of serum, fibrin, and leukocytes. Exudate may ooze from cuts or from areas of infection or inflammation. Types * Purulent or suppurative exudate consists of plasma with both active and dead neutrophils, fibrinogen, and necrotic parenchymal cells. This kind of exudate is consistent with more severe infections, and is commonly referred to as pus. * Fibrinous exudate is composed mainly of fibrinogen and fibrin. It is characteristic of rheumatic carditis, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal Pigment Epithelium
The pigmented layer of retina or retinal pigment epithelium (RPE) is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells. History The RPE was known in the 18th and 19th centuries as the pigmentum nigrum, referring to the observation that the RPE is dark (black in many animals, brown in humans); and as the tapetum nigrum, referring to the observation that in animals with a tapetum lucidum, in the region of the tapetum lucidum the RPE is not pigmented. Anatomy The RPE is composed of a single layer of hexagonal cells that are densely packed with pigment granules. When viewed from the outer surface, these cells are smooth and hexagonal in shape. When seen in section, each cell consists of an outer non-pigmented part containing a large oval nucleus and an inner pigmented portion which extends as a series of straight thread-like processes between the rods, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bruch's Membrane
Bruch's membrane is the innermost layer of the choroid of the eye. It is also called the ''vitreous lamina'' or ''Membrane vitriae'', because of its glassy microscopic appearance. It is 2–4 μm thick. Layers Bruch's membrane consists of five layers (from inside to outside): #the basement membrane of the retinal pigment epithelium #the inner collagenous zone #a central band of elastic fibers #the outer collagenous zone #the basement membrane of the choriocapillaris The retinal pigment epithelium transports metabolic waste from the photoreceptors across Bruch's membrane to the choroid. Embryology Bruch's membrane is present by midterm in fetal development as an elastic sheet. Pathology Bruch's membrane thickens with age, slowing the transport of metabolites. This may lead to the formation of drusen in age-related macular degeneration. There is also a buildup of deposits (Basal Linear Deposits or BLinD and Basal Lamellar Deposits BLamD) on and within the membrane, primarily co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantitative Research
Quantitative research is a research strategy that focuses on quantifying the collection and analysis of data. It is formed from a deductive approach where emphasis is placed on the testing of theory, shaped by empiricist and positivist philosophies. Associated with the natural, applied, formal, and social sciences this research strategy promotes the objective empirical investigation of observable phenomena to test and understand relationships. This is done through a range of quantifying methods and techniques, reflecting on its broad utilization as a research strategy across differing academic disciplines. The objective of quantitative research is to develop and employ mathematical models, theories, and hypotheses pertaining to phenomena. The process of measurement is central to quantitative research because it provides the fundamental connection between empirical observation and mathematical expression of quantitative relationships. Quantitative data is any data that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Acuity
Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal image within the eye, (2) the health and functioning of the retina, and (3) the sensitivity of the interpretative faculty of the brain. The most commonly referred visual acuity is the far acuity (e.g. 6/6 or 20/20 acuity), which describes the examinee's ability to recognize small details at a far distance, and is relevant to people with myopia; however, for people with hyperopia, the near acuity is used instead to describe the examinee's ability to recognize small details at a near distance. A common cause of low visual acuity is refractive error (ametropia), errors in how the light is refracted in the eyeball, and errors in how the retinal image is interpreted by the brain. The latter is the primary cause for low vision in people with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal Detachment
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a surgical emergency. The retina is a thin layer of light-sensitive tissue on the back wall of the eye. The optical system of the eye focuses light on the retina much like light is focused on the film in a camera. The retina translates that focused image into neural impulses and sends them to the brain via the optic nerve. Occasionally, posterior vitreous detachment, injury or trauma to the eye or head may cause a small tear in the retina. The tear allows vitreous fluid to seep through it under the retina, and peel it away like a bubble in wallpaper. Diagnosis Symptoms As the retina is responsible for vision, persons experiencing a retinal detachment have vision loss. This can be painful or painless. Imaging Ultraso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macular Holes
A macular hole is a small break in the macula, located in the center of the eye's light-sensitive tissue called the retina. Symptoms If the vitreous is firmly attached to the retina when it pulls away, it can tear the retina and create a macular hole. Also, once the vitreous has pulled away from the surface of the retina, some of the fibers can remain on the retinal surface and can contract. This increases tension on the retina and can lead to a macular hole. In either case, the fluid that has replaced the shrunken vitreous can then seep through the hole onto the macula, blurring and distorting central vision. Causes The eye contains a jelly-like substance called the vitreous. Shrinking of the vitreous usually causes the hole. As a person ages, the vitreous becomes watery and begins to pull away from the retina. If the vitreous is firmly attached to the retina when it pulls away, a hole can result. Diagnosis Macular degeneration is a condition affecting the tissues ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preferential Hyperacuity Perimetry
Preferential hyperacuity perimetry (PHP) is a psychophysical test used to identify and quantify visual abnormalities such as metamorphopsia and scotoma. It is a type of perimetry. Background Vision abnormalities such as metamorphopsia (distortions) and scotoma are symptoms of retinal diseases such as macular degeneration. In advanced stages of the disease, photoreceptor cells may be irreversibly damaged. Hence, if not treated, macular degeneration may lead to blindness. Awareness to early changes in vision, especially in high risk patients, leads to early treatment (such as intravitreal injection of anti-VEGF factors, e.g. bevacizumab or ranibizumab) and prevents loss of vision. Because of complex brain mechanisms such as filling-in, patients with small and peripheral defects in their vision are often unaware of such changes until late stages in the disease. Another problem is that minute visual aberrations can be normal and therefore should be distinguished from genuine visual ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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