1. DAILY QUESTION March 18, 2009 1. Do you wear corrective lenses (contacts or glasses)? 2. Do you know why you/or others wear these?

2. Agenda3/18/09 Daily Question Daily Question Turn-in: 15-4 Worksheet Turn-in: 15-4 Worksheet The eye packet The eye packet –Notes –Diagram Brain Pop: “Eye” Brain Pop: “Eye” –Quiz Optical Illusions and Conditions of the Eye Optical Illusions and Conditions of the EyeAssignments: 1. No assignment

3. The eye depends on refraction and lenses The operation of the human eye is similar to that of a simple camera: The operation of the human eye is similar to that of a simple camera: –Light enters through a large lens, which focuses the light into an image at the back

4. How the Eye Works Light first enters the eye through: Light first enters the eye through: The cornea The cornea –A transparent tissue –Responsible for 70% of refraction

5. After the cornea, light passes through: After the cornea, light passes through: The pupil The pupil –A hole in the colorful iris From there, light travels through: From there, light travels through: The lens The lens –Composed of glassy fibers situated behind the iris –The curvature of the lens determines how much further the lens refracts light –Muscles can adjust the curvature of the lens until the image is focused

6. The image is focused on the back of the eye, The image is focused on the back of the eye, The retina The retina –Composed of tiny structures that are sensitive to light  Rods and Cones The signal is then sent to the brain via the optic nerve where they are interpreted as images The signal is then sent to the brain via the optic nerve where they are interpreted as images

7. Rods Rods –Outer edges of the retina –More sensitive to dim light –Cannot resolve details very well Cones Cones –In the center of the retina –Responsible for color vision –Only respond to bright light

8. Problems of the Eye Myopia – Nearsighted Myopia – Nearsighted Presbyopia – “Old Man’s Eyes” Presbyopia – “Old Man’s Eyes” Age-related Macular Degenration Age-related Macular Degenration Cataracts Cataracts Diabetic Retinopathy Diabetic Retinopathy Glaucoma Glaucoma Legal Blindness Legal Blindness

9. Eye Safety 90% of eye injuries could be prevented 90% of eye injuries could be prevented

10. Eye Opening Facts More than ½ of all the people in the US use some type of lens to correct their vision More than ½ of all the people in the US use some type of lens to correct their vision Babies have poor vision at birth Babies have poor vision at birth Your eyes look red in pictures because the flash reflects off the choroid, blood vessels that nourish the retina Your eyes look red in pictures because the flash reflects off the choroid, blood vessels that nourish the retina