News tagged with eye

Related topics: brain · nerve cells · current biology · retina

Half the world to be short-sighted by 2050

Half the world's population (nearly 5 billion) will be short-sighted (myopic) by 2050, with up to one-fifth of them (1 billion) at a significantly increased risk of blindness if current trends continue, says a study published ...

Feb 17, 2016
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Why smiles (and frowns) are contagious

Smile! It makes everyone in the room feel better because they, consciously or unconsciously, are smiling with you. Growing evidence shows that an instinct for facial mimicry allows us to empathize with and even experience ...

Feb 11, 2016
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Eye

Eyes are organs that detect light, and send signals along the optic nerve to the visual and other areas of the brain[citation needed]. Complex optical systems 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 cnidaria, molluscs, chordates, annelids and arthropods.

The simplest "eyes", such as those in unicellular organisms, 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.

This text uses material from Wikipedia, licensed under CC BY-SA

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