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Retinal Nerve Fiber Layer
The retinal nerve fiber layer (RNFL) or nerve fiber layer, stratum opticum, is part of the anatomy of the eye. Physical structure The RNFL formed by the expansion of the fibers of the optic nerve; it is thickest near the optic disc, gradually diminishing toward the ora serrata. As the nerve fibers pass through the lamina cribrosa sclerae they lose their medullary sheaths and are continued onward through the choroid and retina as simple axis-cylinders. When they reach the internal surface of the retina they radiate from their point of entrance over this surface grouped in bundles, and in many places arranged in plexuses. Most of the fibers are centripetal, and are the direct continuations of the axis-cylinder processes of the cells of the ganglionic layer, but a few of them are centrifugal and ramify in the inner plexiform and inner nuclear layers, where they end in enlarged extremities. Measurement RNFL measurement can be made by Optical coherence tomography. Relatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the photographic film, film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by Chemical synapse, synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rod cell, rods and cone cell, cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Nuclear Layer
In the anatomy of the eye, the inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, of which there are three varieties: bipolar cells, horizontal cells, and amacrine cells. Bipolar cells The bipolar cells, by far the most numerous, are round or oval in shape, and each is prolonged into an inner and an outer process. They are divisible into rod bipolars and cone bipolars. * The inner processes of the rod bipolars run through the inner plexiform layer and arborize around the bodies of the cells of the ganglionic layer; their outer processes end in the outer plexiform layer in tufts of fibrils around the button-like ends of the inner processes of the rod granules. * The inner processes of the cone bipolars ramify in the inner plexiform layer in contact with the dendrites of the ganglionic cells. Connection types Midget bipolars are linked to one cone while diffuse bipolars take groups of receptors. Diffuse bipolars ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pattern Of Retinal Nerve Fibers
A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometry, geometric shapes and typically repeated like a wallpaper design. Any of the senses may directly observe patterns. Conversely, abstract patterns in science, mathematics, or language may be observable only by analysis. Direct observation in practice means seeing visual patterns, which are widespread in nature and in art. Visual patterns in nature are often Chaos theory, chaotic, rarely exactly repeating, and often involve fractals. Natural patterns include spirals, meanders, waves, foams, tessellation, tilings, fracture, cracks, and those created by Symmetry, symmetries of rotation symmetry, rotation and reflection symmetry, reflection. Patterns have an underlying Mathematics, mathematical structure; indeed, mathematics can be seen as the search for regularities, and the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phacoemulsification
Phacoemulsification is a cataract surgery method in which the internal lens of the eye which has developed a cataract is emulsified with the tip of an ultrasonic handpiece and aspirated from the eye. Aspirated fluids are replaced with irrigation of balanced salt solution to maintain the volume of the anterior chamber during the procedure. This procedure minimises the incision size and reduces the recovery time and risk of surgery-induced astigmatism. It is best suited to relatively soft cataracts, where the ultrasonic energy required is moderate, and insertion of foldable intraocular prosthetic lenses, which take advantage of the small incision possible. It is the most common procedure for cataract removal in the developed world, with an excellent prognosis in uncomplicated cases. Etymology The term originated from phaco- (Greek ''phako-'', comb. form of ''phakós'', lentil; see lens) + emulsification. Contraindications The same general contraindications for cataract surgery a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemistry, Biochemical events lead to characteristic cell changes (Morphology (biology), morphology) and death. These changes include Bleb (cell biology), blebbing, Plasmolysis, cell shrinkage, Karyorrhexis, nuclear fragmentation, Pyknosis, chromatin condensation, Apoptotic DNA fragmentation, DNA fragmentation, and mRNA decay. The average adult human loses 50 to 70 1,000,000,000, billion cells each day due to apoptosis. For the average human child between 8 and 14 years old, each day the approximate loss is 20 to 30 billion cells. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibromyalgia
Fibromyalgia (FM) is a functional somatic syndrome with symptoms of widespread chronic pain, accompanied by fatigue, sleep disturbance including awakening unrefreshed, and Cognitive deficit, cognitive symptoms. Other symptoms can include headaches, Abdominal pain, lower abdominal pain or cramps, and Depression (mood), depression. People with fibromyalgia can also experience insomnia and extreme sensitivity. The causes of fibromyalgia are unknown, with several pathophysiologies proposed. People with fibromyalgia are sometimes accused of imagining their symptoms. Fibromyalgia was first recognised in the 1950s, and defined in 1990, with updated criteria in 2011, 2016, and 2019. Fibromyalgia is estimated to affect 2 to 4% of the population. Women are affected more than men. Rates appear similar across areas of the world and among varied cultures. Symptoms of fibromyalgia are persistent in most patients. The treatment of fibromyalgia is Symptomatic treatment, symptomatic an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaucoma
Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. A major risk factor for glaucoma is increased pressure within the eye, known as Intraocular pressure, intraocular pressure (IOP). It is associated with old age, a family history of glaucoma, and certain medical conditions or the use of some medications. The word ''glaucoma'' comes from the Ancient Greek word (), meaning 'gleaming, blue-green, gray'. Of the different types of glaucoma, the most common are called open-angle glaucoma and closed-angle glaucoma. Inside the eye, a liquid called Aqueous humour, aqueous humor helps to maintain shape and provides nutrients. The aqueous humor normally drains through the trabecular meshwork. In open-angle glaucoma, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit signals, resulting in a range of signs and symptoms, including physical, cognitive disability, mental, and sometimes psychiatric problems. Symptoms include double vision, vision loss, eye pain, muscle weakness, and loss of Sensation (psychology), sensation or coordination. MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms). In relapsing forms of MS, symptoms may disappear completely between attacks, although some permanent neurological problems often remain, especially as the disease advances. In progressive forms of MS, bodily function slowly deteriorates once symptoms manifest and will steadily worsen if left untreated. While its cause is unclear, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Neuritis
Optic neuritis (ON) is a debilitating condition that is defined as inflammation of cranial nerve II which results in disruption of the neurologic pathways that allow visual sensory information received by the retina to be able to be transmitted to the visual cortex of the brain. This disorder of the optic nerve may arise through various pathophysiologic mechanisms, such as through Demyelinating disease, demyelination or inflammation, leading to partial or total loss of vision. Optic neuritis may be a result of standalone idiopathic disease, but is often a manifestation that occurs secondary to an underlying disease. Signs of ON classically present as sudden-onset visual impairment in one or both eyes that can range in severity from mild visual blurring to complete blindness in the affected eye(s). Although pain is typically considered a hallmark feature of optic neuritis, the absence of pain does not preclude a diagnosis or consideration of ON as some patients may report painlessne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a member of a group of genetic disorders called inherited retinal dystrophy (IRD) that cause loss of vision. Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). As peripheral vision worsens, people may experience " tunnel vision". Complete blindness is uncommon. Onset of symptoms is generally gradual and often begins in childhood. Retinitis pigmentosa is generally inherited from one or both parents. It is caused by genetic variants in nearly 100 genes. The underlying mechanism involves the progressive loss of rod photoreceptor cells that line the retina of the eyeball. The rod cells secrete a neuroprotective substance (rod-derived cone viability factor, RdCVF) that protects the cone cells from apoptosis. When these rod cells die, this substance is no longer provided. This is generally followed by the loss of cone photoreceptor cells. Diagnosis is through eye examination of the retina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Coherence Tomography
Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or other scattering media. It uses interferometry techniques to detect the amplitude and time-of-flight of reflected light. OCT uses transverse sample scanning of the light beam to obtain two- and three-dimensional images. Short-coherence-length light can be obtained using a superluminescent diode (SLD) with a broad spectral bandwidth or a broadly tunable laser with narrow linewidth. The first demonstration of OCT imaging (in vitro) was published by a team from MIT and Harvard Medical School in a 1991 article in the journal ''Science (journal), Science''. The article introduced the term "OCT" to credit its derivation from optical coherence-domain reflectometry, in which the axial resolution is based on temporal coherence. The first demonstrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Plexiform
The inner plexiform layer is an area of the retina that is made up of a dense reticulum of fibrils formed by interlaced dendrites of retinal ganglion cells and cells of the inner nuclear layer In the anatomy of the eye, the inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, of which there are three varieties: bipolar cells, horizontal cells, and amacrine cells. Bipolar cell .... Within this reticulum a few branched spongioblasts are sometimes embedded. References External links Overview at utah.edu * Human eye anatomy {{eye-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
