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Macula
The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. The anatomical macula at a size of is much larger than the clinical macula which, at a size of , corresponds to the anatomical fovea. The macula is responsible for the central, high-resolution, color vision that is possible in good light. This kind of vision is impaired if the macula is damaged, as in macular degeneration. The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The term macula lutea comes from Latin ''macula'', "spot", and ''lutea'', "yellow". Structure The macula is an oval-shaped pigmented area in the center of the retina of the human eye and other animal eyes. Its center is shifted slightly away from the optical axi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macular Degeneration
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no symptoms. Some people experience a gradual worsening of vision that may affect one or both eyes. While it does not result in complete blindness, loss of central vision can make it hard to recognize faces, drive, read, or perform other activities of daily life. Visual release hallucinations, Visual hallucinations may also occur. Macular degeneration typically occurs in older people, and is caused by damage to the macula of retina, macula of the retina. Genetic factors and smoking may play a role. The condition is diagnosed through a complete eye exam. Severity is divided into early, intermediate, and late types. The late type is additionally divided into "dry" and "wet" forms, with the dry form making up 90% of cases. The difference between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macula Lutea
The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. The anatomical macula at a size of is much larger than the clinical macula which, at a size of , corresponds to the anatomical fovea. The macula is responsible for the central, high-resolution, color vision that is possible in good light. This kind of vision is impaired if the macula is damaged, as in macular degeneration. The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The term macula lutea comes from Latin ''macula'', "spot", and ''lutea'', "yellow". Structure The macula is an oval-shaped pigmented area in the center of the retina of the human eye and other animal eyes. Its center is shifted slightly away from the optical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fovea Centralis
The ''fovea centralis'' is a small, central pit composed of closely packed Cone cell, cones in the eye. It is located in the center of the ''macula lutea'' of the retina. The ''fovea'' is responsible for sharp central visual perception, vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading (activity), reading and driving. The fovea is surrounded by the ''parafovea'' belt and the ''perifovea'' outer region. The ''parafovea'' is the intermediate belt, where the Retinal ganglion cell, ganglion cell layer is composed of more than five layers of cells, as well as the highest density of cones; the ''perifovea'' is the outermost region where the ganglion cell layer contains two to four layers of cells, and is where visual acuity is below the optimum. The ''perifovea'' contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Eye
The human eye is a sensory organ in the visual system that reacts to light, visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and Balance (ability), keeping balance. The eye can be considered as a living optics, optical device. It is approximately spherical in shape, with its outer layers, such as the outermost, white part of the eye (the sclera) and one of its inner layers (the pigmented choroid) keeping the eye essentially stray light, light tight except on the eye's optic axis. In order, along the optic axis, the optical components consist of a first lens (the cornea, cornea—the clear part of the eye) that accounts for most of the optical power of the eye and accomplishes most of the Focus (optics), focusing of light from the outside world; then an aperture (the pupil) in a Diaphragm (optics), diaphragm (the Iris (anatomy), iris—the coloured part of the eye) that controls the amount of light entering the interior of the eye; then an ... [...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] |
Umbo (eye)
The foveola is located within a region called the macula, a yellowish, cone photoreceptor filled portion of the human retina. Approximately 0.35 mm in diameter, the foveola lies in the center of the fovea and contains only cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...s and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer, and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye. The center of the foveola is sometimes referred to as the umbo, a small (150-200μm) center of the floor of the foveola; features elongated cones. The umbo is the observed point corresponding to the normal light reflex but not solely respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perifovea
Perifovea is a region in the retina that circumscribes the parafovea and fovea and is a part of the macula lutea. The perifovea is a belt that covers a 10° radius around the fovea and is 1.5 mm wide. The perifovea ends when the Henle's fiber layer disappears and the ganglion cells are one-layered. Additional images File:Macula lutea.svg, Schematic diagram of the macula lutea of the retina, showing perifovea, parafovea, fovea, and clinical macula File:Retina-OCT800.png, Time-Domain OCT of the macular area of a retina at 800 nm, axial resolution 3 μm File:SD-OCT Macula Cross-Section.png, Spectral-Domain OCT macula cross-section scan. File:Macula Histology OCT.jpg, alt=macula histology (OCT), macula histology (OCT) File:Retinography.jpg, A fundus photograph showing the macula as a spot to the left. The optic disc is the area on the right where blood vessels converge. The grey, more diffuse spot in the centre is a shadow artifact. See also * Eye movements in reading * Fixati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parafovea
Parafovea or the parafoveal belt is a region in the retina that circumscribes the fovea and is part of the macula lutea. It is circumscribed by the perifovea. Effect on reading In reading, information within 1° (approximately 6–8 characters) of the point of fixation is processed in foveal vision, while information up to 6° of visual angle benefits from parafoveal preview. Studies have shown that people can tell the difference in the letters of a word in the fovea and near-parafovea (the part of the parafovea closest to the fovea), but not in the outer edges of the parafovea. In languages that read from left to right, the word immediately to the right of the fixated word is known as the parafoveal word. Information present in the parafovea can interact with information present in the fovea. The benefit the parafoveal preview has is also mediated by how common the word in the parafovea is, with less common words providing less of a reduction in fixation duration when they reach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foveola
The foveola is located within a region called the macula, a yellowish, cone photoreceptor filled portion of the human retina. Approximately 0.35 mm in diameter, the foveola lies in the center of the fovea and contains only cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...s and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer, and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye. The center of the foveola is sometimes referred to as the umbo, a small (150-200μm) center of the floor of the foveola; features elongated cones. The umbo is the observed point corresponding to the normal light reflex but not solely respo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umbo (eye)
The foveola is located within a region called the macula, a yellowish, cone photoreceptor filled portion of the human retina. Approximately 0.35 mm in diameter, the foveola lies in the center of the fovea and contains only cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...s and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer, and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye. The center of the foveola is sometimes referred to as the umbo, a small (150-200μm) center of the floor of the foveola; features elongated cones. The umbo is the observed point corresponding to the normal light reflex but not solely respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foveola
The foveola is located within a region called the macula, a yellowish, cone photoreceptor filled portion of the human retina. Approximately 0.35 mm in diameter, the foveola lies in the center of the fovea and contains only cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...s and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer, and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye. The center of the foveola is sometimes referred to as the umbo, a small (150-200μm) center of the floor of the foveola; features elongated cones. The umbo is the observed point corresponding to the normal light reflex but not solely respo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
