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SPECIAL SENSES > VISION part III > Flashcards

VISION part III Flashcards

1
Q

innermost layer of the eyeball

A

NERVOUS TUNIC/RETINA

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2
Q

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

A

RETINA

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3
Q

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

A

OPTIC DISC

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4
Q

2 LAYERS OF RETINA

A
  • PIGMENTED LAYER
  • NEURAL LAYER
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5
Q
  • 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
A

PIGMENTED LAYER

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6
Q
  • multilayered outgrowth of the brain
    that processes visual data extensively before sending nerve impulses into axons that form the optic nerve
A

NEURAL LAYER

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7
Q

3 distinct layers of retinal neurons:

A
  • PHOTORECEPTOR LAYER
  • BIPOLAR CELL LAYER (horizontal and amacrine cells)
    GANGLION CELL LAYER
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8
Q

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

A

PHOTORECEPTORS

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9
Q

2 TYPES OF PHOTORECEPTORS

A

RODS AND CONES

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10
Q

HOW MANY RODS ARE IN THE RETINA

A

120 MILLION

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11
Q

HOW MANY CONES ARE IN THE RETINA

A

6 MILLION

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12
Q
  • very sensitive to light (have low light threshold)
  • dim light (black and white vision)
  • PERIPHERAL VISION
A

RODS

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13
Q

RHODOPSIN IS MADE UP OF CHON

A

SCOTOPSIN

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14
Q
  • responsible for color vision
A

CONES

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15
Q

CONE ARE MADE UP OF CHON -

A

PROTOPSIN

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16
Q

derivative of vit. A

A

RETINAL

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17
Q

3 types of CONES

A
  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.
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18
Q

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

A

COLOR BLINDNESS

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19
Q

inability to see well at dim light

A

NIGHT BLINDNESS/NYCTALOPIA

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20
Q

Good vision depends on adequate intake of

A

CAROTENOID

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21
Q

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

A

MACULA LUTEA

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22
Q

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

A

CENTRAL FOVEA

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23
Q

ABILITY TO SEE IMAGES MOST CLEARLY

A

VISUAL ACUITY

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24
Q

SHARPNESS OF VISION

A

RESOLUTION

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25
Q

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.

A

OPTIC DISC

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26
Q

FUNCTIONS OF THE COMPLETE EYE:

A
  1. REFRACTION
  2. ACCOMMODATION
27
Q
  • is the bending of light as it passes from one medium to another.
A

REFRACTION

28
Q

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

A

ACCOMMODATION

29
Q

4 MEDIA OF REFRACTION

A
  1. cornea
  2. aqueous humor
  3. lens
  4. vitreous humor
30
Q

is the crossing point of light rays

A

FOCAL POINT

31
Q

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

A

FOCUSING

32
Q

CHARACTERISTICS OF IMAGES FOCUSED ON THE RETINA:

A
  1. INVERTED/UPSIDE-DOWN
  2. RIGHT TO LEFT REVERSAL
33
Q

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

A

INVERTED/UPSIDE-DOWN

34
Q

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

A

UNDERGO RIGHT TO LEFT REVERSAL

35
Q

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

A

VIEWING AN OBJECT @ 20 ft. DISTANCE

36
Q

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

A

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

37
Q

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

A

accommodation

38
Q

What makes the lens increase in its curvature?

A

 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)

39
Q

 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

A

DISTANT OBJECT (FAR VISION)

40
Q

3 REQUIREMENTS FOR ACCOMMODATION (1)

A
  1. CHANGE IN THE SHAPE
    near vision: increased in curvature
    far vision: decreased in curvature
41
Q

3 REQUIREMENTS FOR ACCOMMODATION (2)

A
  1. CONSTRICTION/DILATION OF THE PUPILS
    bright light: constriction
    dim light: dilation
42
Q

3 REQUIREMENTS FOR ACCOMMODATION (3)

A
  1. CONVERGENCE OF THE EYES
    - medial movement of eyeballs
    (*The nearer the object, the greater is the degree of convergence needed to maintain binocular vision)
43
Q

convergence is not complete, it produces double vision

A

DIPLOPIA

44
Q

minimum distance for near point vision

A

4 inches in young adult

45
Q

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

A

MYOPIA – Nearsightedness

46
Q

causes of myopia

A

a. Elongated eyeball
b. Thickened lens

47
Q

correction for myopia

A

CONCAVE LENS

48
Q

FARSIGHTEDNESS

A

HYPEROPIA/HYPERMETROPIA

49
Q

CAUSES OF HYPEROPIA

A

a. Shortened eyeball
b. Thin lens

50
Q

CORRECTION FOR HYPEROPIA

A

CONVEX LENS

51
Q

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

A

ASTIGMATISM

52
Q

CORRECTION FOR ASTIGMATISM

A

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

53
Q

–inflam of the conjunctiva, from bacterial infxn

A

CONJUNCTIVITIS

54
Q

*Contagious Conjunctivitis:

A

pink eye

55
Q

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

A

CHALAZION

56
Q

infection of an eyelash/hair follicle

A

STYE

57
Q

NEARSIGHTEDNESS

A

MYOPIA

58
Q

FARSIGHTEDNESS

A

HYPEROPIA

59
Q

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

A

PRESBYOPIA

60
Q

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

A

ASTIGMATISM

61
Q

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

A

COLOR BLINDNESS

62
Q

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

A

CATARACT

63
Q
  • 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
A

GLAUCOMA

64
Q

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

A

BLINDNESS

SPECIAL SENSES (7 decks)

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