How can we use lenses to correct vision?

1. How can we use lenses to correct vision?

2. How can we use lenses to correct vision? • If the image is turned upside down too soon, what lens would we use? • What if the image was turned upside down too late? What lens would we use?

4. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

5. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

6. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

7. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

8. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

9. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

10. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

11. No correction needed a. Normal eye Corrected with concave lens b. Nearsightedness-image formed in front of retina c. Farsightedness- image formed behind retina Corrected with convex lens Eyeball too long Eyeball too short

13. Iris: color of eye

15. Iris: color of eye • Lens: double convex

17. Iris: color of eye • Lens: double convex • Cornea: single convex

19. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in

21. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in • Ciliary Muscle: opens up pupil in dim light, closes in bright light

23. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in • Ciliary Muscle: opens up pupil in dim light, closes in bright light • Vitreous humour: transparent jelly of salts and protein

25. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in • Ciliary Muscle: opens up pupil in dim light, closes in bright light • Vitreous humour: transparent jelly of salts and protein • aqueous humour: is a thick watery substance filling the space between the lens and the cornea.

27. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in • Ciliary Muscle: opens up pupil in dim light, closes in bright light • Vitreous humour: transparent jelly of salts and protein • aqueous humour: is a thick watery substance filling the space between the lens and the cornea. • Sclera: white covering

29. Iris: color of eye • Lens: double convex • Cornea: single convex • Pupil: opening that lets light in • Ciliary Muscle: opens up pupil in dim light, closes in bright light • Vitreous humour: transparent jelly of salts and protein • aqueous humour: is a thick watery substance filling the space between the lens and the cornea. • Sclera: white covering • Optic nerve: sends picture to the brain

31. Retina: the picture is upside down here

33. Retina: the picture is upside down here • Made up of millions of tiny, light-sensitive cells called rods and cones

34. Retina: the picture is upside down here • Made up of millions of tiny, light-sensitive cells called rods and cones • Rods: distinguish among black, white and gray; allows you to see in dim light

35. Retina: the picture is upside down here • Made up of millions of tiny, light-sensitive cells called rods and cones • Rods: distinguish among black, white and gray; allows you to see in dim light • Cones: respond to color, 3 types: red, green and blue. Only function in bright light

36. Colorblind? The normal human retina contains two kinds of light sensitive cells: the rod cells (active only in low light) and the cone cells (active in normal daylight and responsible for color perception). Normally, there are three kinds of cones (each one sensitive to a specific range of wavelengths): "red" cones (64%) "green" cones (32%) "blue" cones (2%) The different kinds of inherited color blindness result from partial or complete loss of function of one or more of the different cone systems.

37. Different Types of Color Blindness • Monochromacy: occurs when two or all three of the cone pigments are missing and color and lightness vision is reduced to one dimension. • Total color blindness-see everything as white, black and shades of gray • Dichromacy: occurs when only one of the cone pigments is missing and color is reduced to two dimensions. • Partial color blindness red-green blue-yellow