News tagged with eyeball
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement. In higher organisms the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.
The simplest "eyes", such as those in microorganisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment.
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A new type of firework caused severe eye injuries and blindness in children and adults at last year's bonfire night celebrations, warn doctors in a letter to this week's BMJ.
Health Oct 02, 2012 | not rated yet | 1
Descendants of a British mutiny who have lived for generations in the Pacific have among the lowest rates of myopia in the world, according to an Australian study.
Ophthalmology Jul 20, 2012 | not rated yet | 0
University of Texas Medical Branch at Galveston researchers have discovered that a drug already prescribed to millions of people with diabetes could also have another important use: treating one of the world's leading causes ...
Ophthalmology May 07, 2012 | 5 / 5 (1) | 0 |