Ch 2. Light and the Eyes

Question 1

amount of light

Answer 1

photons

Question 2

light travel in a straight line in what?

Answer 2

homologous medium

Question 3

3 way interaction

Answer 3

light, object, observer

Question 4

6 extra-oscular muscles

Answer 4

4 rectus muscles (run straight back), 2 oblique

Question 5

Non-optical eye parts

Answer 5

sclera(outer layer), choroid (mid), extra ocular muscles

Question 6

strabismus

Answer 6

A disorder of the extraocular muscles in which the two eyes are not aligned with one another, resulting in a double image, which impairs binocular depth perception.

Question 7

amblyopia

Answer 7

A condition in which both eyes develop normally but the neural signals from one eye aren’t processed properly, so that fine vision doesn’t develop in that eye.

Question 8

Optical eye parts

Answer 8

Cornea
Aqueous
Iris/pupil
Crystalline Lens
Vitreous

Question 9

What focuses light?

Answer 9

Cornea and fluids (humors), mostly, and the lends adjusts shape for object distance

Question 10

effects of distance

Answer 10

• near objects will be in focus further from the lens

- far objects in focus nearer to lens

Question 11

accomodation

Answer 11

change lens shape to focus. Skinny ‘weak’ lends for far focal point, fat ‘strong’ lens for close local point (due to ciliary muscles contraction)`

Question 12

Old eyes

Answer 12

yellow lens, reduce pupil function, presbyopia (old eye), distance of dear point increases (from lens hardening and weakening of ciliary muscles)

Question 13

myopia

Answer 13

nearsighted, eye is too long, too much optical pwr, focus point is in front of retnia

Question 14

hyperopia

Answer 14

farsighted, eye too short, low optical pwr,

Question 15

Astigmatism

Answer 15

• Cylindrical error
• Cornea is lemon-, rather than orange-shaped
• Point image brought into focus in two places
  e. g. horizontal and vertical lines may not both be in focus

Question 16

Cataract

Answer 16

Opacity of the lens prevents clear vision
Typically occurs later in life, but seen in infants
Corrected by removing lens and using either spectacle correction or intraocular lens implants

Question 17

Corneal Opacities

Answer 17

cloudy lens

Question 18

Floaters

Answer 18

Shadows on the retina thrown by debris within the vitreous humor; perceived as small, semitransparent spots or threads that appear to be floating before the person’s eyes and tend to move with the eyes.

Question 19

Rods V.s cones location

Answer 19

cones in the fovea then get less as go out, no rods in the fovea but lots as you go out

Question 20

Wavelength names and positions

Answer 20

-blue=scones at lowest point
-rods next
green=m cones at medium
red=l cones for longest wavelength