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Eye Eye is the organ of vision. It detects light and converts it into impulse in a neuron. That impulse travels to the brain where image is formed. How eye evolved was a subject of significant study. First eyes were just simple fotocells. They they evolved in such way that area lifted around those fotocells. Through time that formed what is now knows as eye socket. Furthermore eye socket was filled with transparent liquid and that is how modern eye started. As Darwin put it, it is one of the most remarkable creations of evolution. Eyes are adapted to the enviroment and life requirements of the organism to which they belong. There are many types of eyes such as compund eyes found in insects, eyes adopted to night vision such as the eyes of cats, eyes for fast tracking of pray found on species such as eagles and hawks. Human eye has a lot of chemical compounds called rods and cones. Rods detect light in general and create monochromatic picture. Cones detect color of the light and then brain colors the picture acordingly. Furthermore human eye is capable of changing the focal length of its aparatus and thus is capable of refocusing image at any distance. Even though human eyes are fairly good, they carry some “Evolutionary baggage”. That is why human eye has third eyelid. Something we see highly developped with snakes and cats. It is used to keep our eyes moist. Other flaw of human eye is that it is blind on one spot where optic nerve connects to the eye. Each eye is controlled by six muscles. Those muscles contract in such way that eye almost never moves left, right, up or down. It only rotates. That can really be noticed when people fall asleep, as then they enter REM stage. That stands for rapid eye movement. During that stage of sleep our eyes repidly move in all directions. Ciliary muscles around the eyes compress them in such way to change their focal length. That enables us to use them to look far away, and also really close. Human eye can focus up to 20cm for long time, without putting any strain on the eye. Human eye has field of view (shortened FOV) of about 95 degrees to left and right. To down FOV is 75 degrees down and 60 degrees up. Peripheral vision is up to 180 degrees to left and right. Even though our vision has high FOV we can only attain information from small center piece of around 12-15 degrees around the center. Ismet Majstorović

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  • EyeEyeistheorganofvision.Itdetectslightandconvertsitintoimpulseinaneuron.

    Thatimpulsetravelstothebrainwhereimageisformed.Howeyeevolvedwasasubjectofsignificantstudy.Firsteyeswerejustsimple

    fotocells.Theytheyevolvedinsuchwaythatarealiftedaroundthosefotocells.Throughtimethatformedwhatisnowknowsaseyesocket.Furthermoreeyesocketwasfilledwithtransparentliquidandthatishowmoderneyestarted.AsDarwinputit,itisoneofthemostremarkablecreationsofevolution.

    Eyesareadaptedtotheenviromentandliferequirementsoftheorganismtowhichtheybelong.Therearemanytypesofeyessuchascompundeyesfoundininsects,eyesadoptedtonightvisionsuchastheeyesofcats,eyesforfasttrackingofprayfoundonspeciessuchaseaglesandhawks.

    Humaneyehasalotofchemicalcompoundscalledrodsandcones.Rodsdetectlightingeneralandcreatemonochromaticpicture.Conesdetectcolorofthelightandthenbraincolorsthepictureacordingly.Furthermorehumaneyeiscapableofchangingthefocallengthofitsaparatusandthusiscapableofrefocusingimageatanydistance.Eventhoughhumaneyesarefairlygood,theycarrysomeEvolutionarybaggage.Thatiswhyhumaneyehasthirdeyelid.Somethingweseehighlydeveloppedwithsnakesandcats.Itisusedtokeepoureyesmoist.Otherflawofhumaneyeisthatitisblindononespotwhereopticnerveconnectstotheeye.

    Eacheyeiscontrolledbysixmuscles.Thosemusclescontractinsuchwaythateyealmostnevermovesleft,right,upordown.Itonlyrotates.Thatcanreallybenoticedwhen people fall asleep, as then they enter REMstage. That stands for rapid eyemovement.Duringthatstageofsleepoureyesrepidlymoveinalldirections.Ciliarymusclesaroundtheeyescompresstheminsuchwaytochangetheirfocallength.Thatenablesustousethemtolookfaraway,andalsoreallyclose.Humaneyecanfocusupto20cmforlongtime,withoutputtinganystrainontheeye.

    Humaneyehasfieldofview(shortenedFOV)ofabout95degreestoleftandright.TodownFOVis75degreesdownand60degreesup.Peripheralvisionisupto180degreestoleftandright.EventhoughourvisionhashighFOVwecanonlyattaininformationfromsmallcenterpieceofaround1215degreesaroundthecenter.

    IsmetMajstorovi


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