The Eye 
How the eye works and functions
EYEThe eye is an extension of the brainVisit www.worldofteaching.comFor 100’s of free powerpointsEye brain proxomityCan you see : the optic nerve bundle?Spinal cord?Cross sectionYou must know the position of:RetinaLensCorneaScleroticOptic nerveCilary musclesSuspensory ligamentsRetina –receives the imageFull of light receptors which are sensitive to:ColourLight levelsMassive blood supply is also neededFovea is the main focal point and has greatest density of light receptorsRetina receptorsLight receptors are called rods and coneFocusing on objectsThe lens and cornea focus the light on the retinaFocusingThe lens job is to make the rays hit the same point The red rays will be out of focusBending lightLight is refracted and bent to focus it as it passes through the lensLens thickness can be changed so the amount of bending is changedNear visionto bend the light more to focus itFat lens neededDistance visionRays enter the eye closer togetherNeed less bendingThinner lens neededChanging lens thicknessThe lens is slightly elastic, its relaxed state is short and fat.Cilary muscles are attached to the lens, when contracted they pull the lens thinControlling light levelsYour eye are very sensitive and can be damaged by harsh light. Your iris controls light allowed into the eye by changing the size of the pupil