The eye and Image formation

Question 1

What are the steps through which light is transmitted?

Answer 1

Light enters the eye->focused by the cornea and lens onto the retina->photoreceptors (rods and cones)-> bipolar cells-> ganglion cells-> axons are the ones that make up the optic nerve.

Question 2

What makes up the optic nerve?

Answer 2

Axons of ganglion cells make up the optic nerve.

Question 3

Retinal ganglion cells are the only neurons in the retina that ____ ______ ______.

Answer 3

…fire action potentials.

Question 4

What is the set up of the retina?

Answer 4

The photoreceptors are at the back of the retina->horizontal cells-> bipolar cells-> amacrine cells-> ganglion cells->ganglion cell axons make up the optic nerve

Question 5

what is the blind spot and where is it located?

Answer 5

Blind spot- place in the visual field where there is a lack of of photoreceptors and therefore no sensitivity to light. Located at the hole where the optic nerve leaves through.

Question 6

Where is light refracted the most?

Answer 6

Cornea.

About 2/3 of the optical power of your eye is in the cornea and 1/3 is in the lens.

Question 7

What is the pupil?

Answer 7

Hole or black dot in eye.

Question 8

What is the iris?

Answer 8

the muscles tha change the size of the pupil.

Question 9

What is the cornea?

Answer 9

Thin, transparent covering of the eye ball.

Has the effect of bending the light rays that are incident on your eye and along with the lens it bends light rays even further. Combined effect focus the light rays onto the surface of your retina.

The focusing power of the cornea is fixed and cannot be adjusted.

Question 10

What is the lens?

Answer 10

adjustable focus for near/ far.

Focusing power can be adjusted. The lens has muscles attached to it that changes its shape and power.

Question 11

What is the fovea?

Answer 11

Part of the retina corresponding to the central part of visual field. It has a pit shape because the bipolar and ganglion cells are pushed off to the side so that the photoreceptors have a better access to the incoming light.

Question 12

What is the optic disk?

Answer 12

part of the retina corresponding to the blind spot.

Question 13

What is the optic nerve?

Answer 13

made up of ganglion cell axons that exit through the optic disc.

Question 14

What is the aqueous humor?

Answer 14

fluid filled region in front of the lens

Question 15

what is the vitreous humor?

Answer 15

fluid filled region behind the lens.

Question 16

How does an image form?

Answer 16

Light passes through a hole (pupil) and forms an image in the retina. Light will be reflected in many directions. Image is upside down and real.

Question 17

what is visual angle?

Answer 17

tan(ø)= height/ distance

Question 18

What size must a pinhole camera be?

Answer 18

A pin hole must be very smasll in order for it to work properly. The image gets blurred if the hole is large. BUT when the pin hole is too small only a fraction of the light can make it through the opening- a small pin hole cannot operate well in medium or low light level conditions.

Question 19

What is accomodation?

Answer 19

In vision, bringing objects located at different distances into focus by changing the shape of the lens.

Question 20

What is myopia or near-sightedness?

Answer 20

When person cannot see far/ distant away objects.

Eye is too long (or lens is too fat) so that even with relaxed accomodation, far objects are focused IN FRONT OF THE RETINA.

This is corrected with concave lenses.

Question 21

What is hyperopia or far sightedness?

Answer 21

When a person cannot see objects that are close/ near.

The eye is too short (lens that is too thin) even with relaxed accomodation, distant objects are focused behind the retina.

Correct this using convex lens.

Question 22

What is presbyopia?

Answer 22

“aging vision” person may have had perfect vision all their lives and usually find themselves in need of reading glasses by age 50 or so.