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Vision > Vision > Flashcards

Vision Flashcards

1
Q

white part of the eye, composed of tough connective tissue.

A

Sclera

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2
Q

Anteriorly to sclera, the outer layer consists of transparent

A

cornea

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3
Q

contains many blood vessels which nourish the retina

A

choroid

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4
Q

Choroid layer becomes specialized anteriorly to form the

A

ciliary body and iris

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5
Q

contains the rods and cones, the photoreceptors that convert light energy into nerve impulses.

A

retina

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6
Q

has the highest level of visual acuity (i.e. the ability to distinguish between two-point light sources.

A

fovea

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7
Q

The posterior cavity between the lens and retina contains jellylike substance

A

the vitreous humor.

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8
Q

The anterior cavity between cornea and lens contains a clear watery fluid, the _______ _____.
carries nutrients for the cornea and lens and is produced at a rate of about 5 ml/day by a capillary network

A

aqueous humor

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9
Q

The fluid produced by aqueous humor drains into a canal of ________ at the edge of the cornea and eventually enters the blood

A

canaal of schlemm

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10
Q

The condition associated with increased intraocular pressure is known as

A

glaucoma

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11
Q

the second leading cause of blindness in the United States and the leading cause of blindness among African Americans

A

Glaucoma

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12
Q

characterized by progressive optic neuropathy with loss of retinal neurons and the nerve fiber layer, resulting in blindness if left untreated.

A

Glaucoma

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13
Q

results from rapid increases in intraocular pressure. Patients present with a painful, red eye and are at risk of rapid permanent vision loss-medical emergency.

A

Acute closed-angle glaucoma

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14
Q

much more common and presents as painless progressive loss of vision. Typically, the peripheral vision is affected first and the central vision is affected later.

A

Open-angle glaucoma

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15
Q

intraocular pressure is normal, but optic nerve damage and visual field loss still occur

A

Normal-tension, or low-tension glaucoma

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16
Q

results from rapid increases in IOP

A

Acute closed-angle glaucoma

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17
Q

The point on the retina at which the optic nerve leaves and through which blood vessels pass is the

A

optic disc

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18
Q

the neural rim of the optic disc shrinks and the physiologic cup within the optic disc enlarges

A

pathologic “cupping.”

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19
Q

The main goal of glaucoma therapy is to

A

lower intraocular pressure (IOP).

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20
Q

treatment for glaucoma

A

Laser surgery and incisional surgery

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21
Q

drugs to treat glaucoma that decrease aqueous production

A

Carbonic anhydrase inhibitors
Alpha-adrenergic agonists
Beta-adrenergic antagonists

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22
Q

drugs to treat glaucoma that increase aqueous outflow

A

Prostaglandin derivatives
Cholinergic agonists
Alpha-adrenergic agonists

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23
Q

Changing the shape of lens to focus an object is called __________.

A

accommodation

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24
Q

a circular ring of smooth muscle attached to the lens by suspensory ligaments.

A

ciliary muscle

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25
Q

In the normal eye, the ciliary muscle is relaxed and the lens is _____ for far vision. When the ciliary muscle contracts, the lens becomes more ______ and stronger for near vision.

A

flat

convex

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26
Q

fibers on lens, which occasionally become opaque so that light rays cannot pass through, a condition known as

A

cataract

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27
Q

how may cataract be treated

A

defective lens can usually be surgically removed and vision restored by an implanted artificial lens or compensating eyeglasses.

28
Q

With advancing age the lens becomes sclerotic and less flexible. With loss of elasticity, the lens can no longer assume the spherical shape required to accommodate for near vision. This age-related reduction is known as

A

presbyopia

29
Q

caused by uneven curvature of the cornea.

occurs in combination with nearsightedness or farsightedness.

A

Astigmatism

30
Q

Astigmatic errors can be corrected with _______ lenses, frequently in combination with ______ lenses, or with _____ ______ lenses.

A

cylindrical
spherical
hard contact

31
Q

During embryonic development the retinal cells _______ ______ of the nervous system, so the retinal layers are actually facing backward from the incoming light.
Light must pass through several retinal layers before reaching the photoreceptors.

A

“back out”

32
Q

The point on the retina at which the optic nerve leaves and through which blood vessels pass is called the ______, , also often referred to as the blind spot

A

optic disc

33
Q

The area immediately surrounding fovea, ______ ______, also has a high concentration of cones and fairly high acuity, but less than in fovea, because of overlying ganglion and bipolar cells in the macula.

A

macula lutea

34
Q

major cause of gradual or sudden, painless, central vision loss in the elderly, brought on by deterioration of the macula.

A

Age-related Macular Degeneration (AMD)

35
Q

Age-related Macular Degeneration (AMD) occurs in two forms

A

nonexudative (dry) form and an exudative (wet) form.

36
Q

is most common type of macular degeneration and affects 90% of the people who have the condition.

there is a breakdown or thinning of the layer of retinal pigment epithelial cells (RPE) in the macula.

A

Dry AMD (Age-related Macular Degeneration)

37
Q

Loss of the ________ leads to degeneration of photoreceptors resulting in loss of vision in advanced AMD.

A

pigment epithelial cells (RPE)

38
Q

treament for Dry AMD

A

There is no FDA approved treatment for dry AMD.

Some evidence exists, that treatment with vitamins C and E, beta-carotene, and zinc may retard dry macular degeneration

39
Q

Abnormal blood vessel growth (angiogenesis) is a hallmark of _____.

Neovascular vessels from the choroid grow underneath the RPE and leak serum and blood, damaging the macula and causing central vision loss.

A

Exudative macular degeneration (wet AMD)

40
Q

treament for wet AMD

A

Macugen and Lucentis

41
Q

a selective VEGF antagonist

A

Macugen (Pegaptanib)

42
Q

a humanized anti-VEGF antibody fragment that inhibits VEGF activity by competitively binding with VEGF.

A

Lucentis (ranibizumab)

43
Q

monochromatic (single color) receptor, which are highly sensitive to light and allow objects to be seen in low intensity light

A

Rods

44
Q

(increased light sensitivity in response to prolonged darkness) occurs to much greater extent in rods than in cones.

A

Dark adaptation

45
Q

There are three types of cone photoreceptors, with overlapping sensitivity to light of different wavelength:

A
  1. Blue (or S) cones absorb light of short wavelength
  2. Green (or M) cones absorb light of medium wavelength
  3. Red (or L) cones absorb the light at the long wavelength.
46
Q

properties of cones (6)

A 
color vision
low sensitivity
day vision
concentrated in fovea
3 mil per retina
high acuity
47
Q

properties of rods (6)

A 
100 million per retina
Vision in shades of gray
High sensitivity
Low acuity
Night vision
More numerous in periphery
48
Q

deficiency of vitamin A

A

results in night blindness (rod cell dysfunction)

49
Q

xerophthalmia

A

dry eyes that are prone to ulceration and infection

50
Q

follicular hyperkeratosis

A

rough elevations of skin around hair follicles resembling goose bumps

51
Q

common condition in which there is a range of possible defects in color vision.

A

Color blindness

52
Q

common cause of color blindness

A

X-linked recessive mutations are a common cause of defective color vision, resulting in a higher proportion of males than females with this condition

53
Q

The pupillary constrictor fibers release _______, which activates muscarinic AChRs. Sympathetic pupillary fibers release norepinephrine, which activates a1-adrenergic receptors.

A

acetylcholine

54
Q

Drugs that inhibit ________, or that stimulate a1-adrenergic receptors, dilate the pupils, whereas drugs that stimulate _________ or block a1-adrenergic receptors cause pupillary constriction.

A

mAChRs

mAChRs

55
Q

Used as miotics

(to constrict pupil) for control of intraocular pressure in glaucoma

A

Parasympathomimetics

56
Q

Cholinergic agonists of Parasympathomimetics

A

Cholinergic agonists: pilocarine, carbachol, methacholine

57
Q

Used as mydriatics
(to dilate pupil) to aid in eye examination or as cycloplegics
(to relax ciliary muscles)

A

Parasympatholitics

58
Q

Parasympatholitics Anticholinergic agents

A

Mydriatic: eucatropine

59
Q

Cyctoplegic and mydriatic drugs

A

homatropine, scopolamine, atropine, cyclopentolate

60
Q

Sympathomimetics

A

Used for mydriasis; do not cause cycloplegia

61
Q

Sympathomimetics drugs

A

Phenylephrine, hydroxyamphetamine,epinephrine, cocaine

62
Q

Lateral geniculate nucleus

A

in the thalamus separates information received from the eyes and relays it via optic radiation to different zones in the cortex

63
Q

Damage of visual cortex of one side will produce the loss of visual field on the opposite side to the lesion.

Occipital hematoma produce _______ _______ and headache

A

homonymous hemianopia

64
Q

The overlapping area seen by both eyes at the same time is known as the ________, which is important for depth perception.

A

binocular (“two-eyed”) field of vision

65
Q

amblyopia

A

misaligned eyes

66
Q

diplopia

A

double vision

67
Q

Drugs that possess anticholinergic properties that are known to induce visual disturbances.

A

Antihistamines
antipsychotics
tricyclic antidepressants

Vision (1 decks)

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