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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; and this kind of vision is impaired if the macula is damaged, for example 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 ... [...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 or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, 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 hallucinations may also occur. Macular degeneration typically occurs in older people. Genetic factors and smoking also play a role. It is due to damage to the macula of the retina. Diagnosis is by a complete eye exam. The 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 the two forms is the change of macula. Those with dry form AMD have drusen, ... [...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; and this kind of vision is impaired if the macula is damaged, for example 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fovea Centralis
The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina. The fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading and driving. The fovea is surrounded by the ''parafovea'' belt and the ''perifovea'' outer region. The parafovea is the intermediate belt, where the 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 central fovea. That, in turn, is surrounded by a larger peripheral area, which delivers highly com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a 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 film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by 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: rods and cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as well as high-acuity vision used f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeaxanthin
Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji (wolfberries), and many other plants and microbes their characteristic color. The name (pronounced ''zee-uh-zan'-thin'') is derived from '' Zea mays'' (common yellow maize corn, in which zeaxanthin provides the primary yellow pigment), plus ''xanthos'', the Greek word for "yellow" (see xanthophyll). Xanthophylls such as zeaxanthin are found in highest quantity in the leaves of most green plants, where they act to modulate light energy and perhaps serve as a non-photochemical quenching agent to deal with triplet chlorophyll (an excited form of chlorophyll) which is overproduced at high light levels during photosynthesis. Animals derive zeaxanthin from a plant diet. Zeaxanthin is one of the two primary xanthophyll carotenoids contained within the ret ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutein
Lutein (;"Lutein" . from ''luteus'' meaning "yellow") is a and one of 600 known naturally occurring s. Lutein is synthesized only by plants, and like other xanthophylls is found in high quantities in |
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 cells 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 responsible for this light reflex. The anatomy of the foveola was recently reinvestigated. Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License Serial semithin and ultrathin sections, and focuse ... [...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 cells 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 responsible for this light reflex. The anatomy of the foveola was recently reinvestigated. Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License Serial semithin and ultrathin sections, and foc ... [...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 * Fixation ... [...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 cells 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 responsible for this light reflex. The anatomy of the foveola was recently reinvestigated. Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License Serial semithin and ultrathin sections, and foc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
