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Hollenhorst Plaque
A Hollenhorst plaque (also known as a retinal cholesterol embolus) is a cholesterol embolus that is seen in a blood vessel of the retina. It is usually found when a physician performs ophthalmoscopy, during which a plaque will appear as a small, bright crystal that is refractile (reflects the light from the ophthalmoscope) and yellow. This is a medical exam finding, and is not a medical condition, though it may be related to cardiovascular conditions such as atherosclerosis of the internal carotid artery. It was first described by United States, American Ophthalmology, ophthalmologist Robert Hollenhorst in 1961. Cause A Hollenhorst plaque is the result of embolization (breaking off) of cholesterol forming an atheromatous plaque. This occurs in a blood vessel that is upstream of the eye, such as the internal carotid artery on the same side as the eye (ipsilateral), or the aorta. This cholesterol embolus is then able to travel via the bloodstream to distal (downstream) vessels. When ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal Embolism
Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use retinal to convert light into metabolic energy. In fact, a recent study suggests most living organisms on our planet ~3 billion years ago used retinal to convert sunlight into energy rather than chlorophyll. Since retinal absorbs mostly green light and transmits purple light, this gave rise to the Purple Earth hypothesis, Purple Earth Hypothesis. There are many forms of vitamin A — all of which are converted to retinal, which cannot be made without them. Retinal itself is considered to be a form of vitamin A when eaten by an animal. The number of different molecules that can be converted to retinal varies from species to species. Retinal was originally called retinene, and was renamed after it was discovered to be vitamin A aldehyde. Vertebra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
