| A | B |
|---|
| Visible light | the very narrow range of wavelengths and frequencies in the electromagnetic spectrum that humans can see |
| Cornea | a transparent membrane that protects the eye and refracts light |
| Pupil | the opening to the inside of the eye |
| Iris | the colored part of the eye that controls the size of the opening to let in more or less light |
| Lens | the part of the eye that refracts light to focus an image on the back surface of the eye |
| Retina | the back surface of the eye that acts like a screen for the image |
| Nerves | attached to rods and cones in the retina to carry information to the brain |
| Nearsightedness | when the eye is too long and the lens focuses light in front of the retina |
| Farsightedness | when the eye is too short and the lens focuses light behind the retina |
| Concave lens | a lens that is thinner in the middle than at the edges and is used to correct nearsightedness |
| Convex lens | a lens that is thicker in the middle than at the edges and is used to correct farsightedness |
| Color deficiency | a condition in which 5-8% of men and 0.5% of women in the world have trouble distinguishing certain colors |
| near | A nearsighted person can clearly see _____ objects. |
| far | A farsighted person can clearly see ____ objects. |
