DAILY QUESTION

March 18, 2009

1. Do you wear corrective lenses (contacts or glasses)?

2. Do you know why you/or others wear these?

AgendaAgenda 3/18/093/18/09

Daily QuestionDaily Question Turn-in: 15-4 WorksheetTurn-in: 15-4 Worksheet The eye packetThe eye packet

– NotesNotes– DiagramDiagram

Brain Pop: “Eye”Brain Pop: “Eye”– QuizQuiz

Optical Illusions and Conditions of the EyeOptical Illusions and Conditions of the EyeAssignments: Assignments:

1. No assignment 1. No assignment

The eye depends on refraction and The eye depends on refraction and lenseslenses

The operation of the human eye is The operation of the human eye is similar to that of a simple camera:similar to that of a simple camera:– Light enters through a large lens, which Light enters through a large lens, which

focuses the light into an image at the focuses the light into an image at the backback

How the Eye WorksHow the Eye Works

Light first enters the eye through:Light first enters the eye through: The corneaThe cornea

– A transparent tissueA transparent tissue– Responsible for 70% of refractionResponsible for 70% of refraction

After the cornea, light passes through:After the cornea, light passes through: The pupilThe pupil

– A hole in the colorful irisA hole in the colorful iris From there, light travels through:From there, light travels through: The lensThe lens

– Composed of glassy fibers situated behind Composed of glassy fibers situated behind the iristhe iris

– The curvature of the lens determines how The curvature of the lens determines how much further the lens refracts lightmuch further the lens refracts light

– Muscles can adjust the curvature of the lens Muscles can adjust the curvature of the lens until the image is focuseduntil the image is focused

The image is focused on the back of The image is focused on the back of the eye, the eye,

The retinaThe retina– Composed of tiny structures that are Composed of tiny structures that are

sensitive to lightsensitive to light Rods and ConesRods and Cones

The signal is then sent to the brain The signal is then sent to the brain via the optic nerve where they are via the optic nerve where they are interpreted as imagesinterpreted as images

RodsRods– Outer edges of the Outer edges of the

retinaretina– More sensitive to More sensitive to

dim lightdim light– Cannot resolve Cannot resolve

details very welldetails very well

ConesCones– In the center of the In the center of the

retinaretina– Responsible for Responsible for

color visioncolor vision– Only respond to Only respond to

bright lightbright light

Problems of the EyeProblems of the Eye

Myopia – NearsightedMyopia – Nearsighted Presbyopia – “Old Man’s Eyes”Presbyopia – “Old Man’s Eyes” Age-related Macular DegenrationAge-related Macular Degenration CataractsCataracts Diabetic RetinopathyDiabetic Retinopathy GlaucomaGlaucoma Legal BlindnessLegal Blindness

Eye SafetyEye Safety

90% of eye injuries could be 90% of eye injuries could be preventedprevented

Eye Opening FactsEye Opening Facts

More than ½ of all the people in the More than ½ of all the people in the US use some type of lens to correct US use some type of lens to correct their visiontheir vision

Babies have poor vision at birthBabies have poor vision at birth Your eyes look red in pictures Your eyes look red in pictures

because the flash reflects off the because the flash reflects off the choroid, blood vessels that nourish choroid, blood vessels that nourish the retinathe retina