VISION part III

Question 1

innermost layer of the eyeball

Answer 1

NERVOUS TUNIC/RETINA

Question 2

the inner coat of the eyeball, lines the posterior three-quarters of
the eyeball and is the beginning of the visual pathway

Answer 2

RETINA

Question 3

is the site where the optic (II) nerve exits the eyeball. Bundled together with the optic nerve are the two blood supply: central retinal artery,
a branch of the ophthalmic artery, and the central retinal vein

Answer 3

OPTIC DISC

Question 4

2 LAYERS OF RETINA

Answer 4

• PIGMENTED LAYER
• NEURAL LAYER

Question 5

• non-visual portion of retina
  -It is a sheet of melanin-containing epithelial cells located between the choroid
  and the neural part of the retina

Answer 5

PIGMENTED LAYER

Question 6

• multilayered outgrowth of the brain
  that processes visual data extensively before sending nerve impulses into axons that form the optic nerve

Answer 6

NEURAL LAYER

Question 7

3 distinct layers of retinal neurons:

Answer 7

• PHOTORECEPTOR LAYER
• BIPOLAR CELL LAYER (horizontal and amacrine cells)
  GANGLION CELL LAYER

Question 8

are specialized cells in the photoreceptor layer that begin the process by which light rays are ultimately converted to nerve impulses

Answer 8

PHOTORECEPTORS

Question 9

2 TYPES OF PHOTORECEPTORS

Answer 9

RODS AND CONES

Question 10

HOW MANY RODS ARE IN THE RETINA

Answer 10

120 MILLION

Question 11

HOW MANY CONES ARE IN THE RETINA

Answer 11

6 MILLION

Question 12

• very sensitive to light (have low light threshold)
• dim light (black and white vision)
• PERIPHERAL VISION

Answer 12

RODS

Question 13

RHODOPSIN IS MADE UP OF CHON

Answer 13

SCOTOPSIN

Question 14

• responsible for color vision

Answer 14

CONES

Question 15

CONE ARE MADE UP OF CHON -

Answer 15

PROTOPSIN

Question 16

derivative of vit. A

Answer 16

RETINAL

Question 17

3 types of CONES

Answer 17

1. Blue cones, which are sensitive to blue light.
2. Green cones, which are sensitive to green light.
3. Red cones, which are sensitive to red light.

Question 18

inability to distinguish between certain colors because of the absence or deficiency of 1 or 3 photopigment

Answer 18

COLOR BLINDNESS

Question 19

inability to see well at dim light

Answer 19

NIGHT BLINDNESS/NYCTALOPIA

Question 20

Good vision depends on adequate intake of

Answer 20

CAROTENOID

Question 21

a small yellow spot near the center of the posterior portion of the retina

Answer 21

MACULA LUTEA

Question 22

A small pit/depression at the center of the
macula lutea. It contains only CONES, thus, the area of highest visual acuity or resolution

Answer 22

CENTRAL FOVEA

Question 23

ABILITY TO SEE IMAGES MOST CLEARLY

Answer 23

VISUAL ACUITY

Question 24

SHARPNESS OF VISION

Answer 24

RESOLUTION

Question 25

BLIND SPOT is a white spot just medial to the macula lutea. Where blood vessels, optic nerve enter the eyes. It contains no photoreceptors, thus objects focused on this area cannot be seen.

Answer 25

OPTIC DISC

Question 26

FUNCTIONS OF THE COMPLETE EYE:

Answer 26

1. REFRACTION 2. ACCOMMODATION

Question 27

- is the bending of light as it passes from one medium to another.

Answer 27

REFRACTION

Question 28

is a process by which the lens of the eye changes in shape/curvature to adjust for vision at various distances; the lens either increase/decrease in its curvature

Answer 28

ACCOMMODATION

Question 29

4 MEDIA OF REFRACTION

Answer 29

1. cornea 2. aqueous humor 3. lens 4. vitreous humor

Question 30

is the crossing point of light rays

Answer 30

FOCAL POINT

Question 31

is the process of causing light to converge (bend toward each other

Answer 31

FOCUSING

Question 32

CHARACTERISTICS OF IMAGES FOCUSED ON THE RETINA:

Answer 32

1. INVERTED/UPSIDE-DOWN 2. RIGHT TO LEFT REVERSAL

Question 33

what is the image seen on the retina when there is a convergence of light rays

Answer 33

INVERTED/UPSIDE-DOWN

Question 34

what is the image seen on the retina when the light from right side strikes the left side of the object and vice versa

Answer 34

UNDERGO RIGHT TO LEFT REVERSAL

Question 35

The light rays reflected from the object are nearly PARALLEL to one another

Answer 35

VIEWING AN OBJECT @ 20 ft. DISTANCE

Question 36

Light rays that are reflected from the object are DIVERGENT ( they move away from each other

Answer 36

VIEWING AN OBJECT - NEAR OBJECT (NEAR VISION)/CLOSER THAN 20 ft.

Question 37

Thus, when viewing at closer objects, light rays must be refracted more to allow the image to be focused on the retina called

Answer 37

accommodation

Question 38

What makes the lens increase in its curvature?

Answer 38

 The CONTRACTION of the ciliary muscle, allowing the ciliary process & choroid to be pulled forward toward the lens -- this action releases tension on the lens & on the suspensory ligaments  Because the lens is elastic, it changes its shape: shortens, thickens, bulges (increase in convexity)

Question 39

 In order to accommodate light rays, the ciliary muscles should RELAX, causing the suspensory ligaments to exert greater tension on the lens, thus the lens becomes more flat: stretched in all direction by the suspensory ligaments decreased convexity of the lens

Answer 39

DISTANT OBJECT (FAR VISION)

Question 40

3 REQUIREMENTS FOR ACCOMMODATION (1)

Answer 40

1. CHANGE IN THE SHAPE near vision: increased in curvature far vision: decreased in curvature

Question 41

3 REQUIREMENTS FOR ACCOMMODATION (2)

Answer 41

2. CONSTRICTION/DILATION OF THE PUPILS bright light: constriction dim light: dilation

Question 42

3 REQUIREMENTS FOR ACCOMMODATION (3)

Answer 42

3. CONVERGENCE OF THE EYES - medial movement of eyeballs (*The nearer the object, the greater is the degree of convergence needed to maintain binocular vision)

Question 43

convergence is not complete, it produces double vision

Answer 43

DIPLOPIA

Question 44

minimum distance for near point vision

Answer 44

4 inches in young adult

Question 45

Image is focused in front of the retina, thus the person has to move closer to the object to allow clearer vision

Answer 45

MYOPIA – Nearsightedness

Question 46

causes of myopia

Answer 46

a. Elongated eyeball b. Thickened lens

Question 47

correction for myopia

Answer 47

CONCAVE LENS

Question 48

FARSIGHTEDNESS

Answer 48

HYPEROPIA/HYPERMETROPIA

Question 49

CAUSES OF HYPEROPIA

Answer 49

a. Shortened eyeball b. Thin lens

Question 50

CORRECTION FOR HYPEROPIA

Answer 50

CONVEX LENS

Question 51

The cornea’s curvature is asymmetrical, so light rays are focused at 2 points on the retina, rather than at one point resulting to: o blurred vision, shadows on the letters, squinting o double vision

Answer 51

ASTIGMATISM

Question 52

CORRECTION FOR ASTIGMATISM

Answer 52

Eyeglasses wherein its anterior outer surface corrects visual defects & the posterior surface. Matches the curvature of the cornea.

Question 53

–inflam of the conjunctiva, from bacterial infxn

Answer 53

CONJUNCTIVITIS

Question 54

*Contagious Conjunctivitis:

Answer 54

pink eye

Question 55

– a cyst caused by infection of the sebaceous glands along the edge of the eyelids

Answer 55

CHALAZION

Question 56

infection of an eyelash/hair follicle

Answer 56

STYE

Question 57

NEARSIGHTEDNESS

Answer 57

MYOPIA

Question 58

FARSIGHTEDNESS

Answer 58

HYPEROPIA

Question 59

decrease in the ability of the eye to accommodate for near vision; comes with aging

Answer 59

PRESBYOPIA

Question 60

a defect in which the cornea or lens is not uniformly curved & the image is not sharply focused

Answer 60

ASTIGMATISM

Question 61

absence of perception of 1 or more colors; most of which have genetic origin

Answer 61

COLOR BLINDNESS

Question 62

most common cause of blindness -clouding of the lens as a result of aging, infection or trauma; also excessive exposure to UV rays

Answer 62

CATARACT

Question 63

- excessive pressure build up; results from an interference with normal circulation of AH or from overproduction - tunnel vision/increase of IOP - lost of peripheral vision

Answer 63

GLAUCOMA

Question 64

*increase pressure w/in the eye can interfere with circulation & may lead to malfunction/destruction of the optic nerve

Answer 64

BLINDNESS