Lec 26 Visual System and Gaze Disorders Flashcards

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1
Q

What are the 3 layers of the eye?

A

external: sclera and cornea
intermediate: iris, ciliary body, choroid
internal: retina

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2
Q

What is the iris?

A

circular pigmented membrane enclosing pupil

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3
Q

What is the ciliary body?

A

just beneath sclera + lateral to lens
makes aqueous humor
contains ciliary muscle that allows lens to change shape to focus

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4
Q

What is the choroid?

A

layer of connective tissue and blood vessels between sclera and retina
suplles nutrients to the eye

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5
Q

What are the three fluid compartments of the eye?

A
  • anterior and posterior chambers in front of lens [separated by iris]
  • vitreous body [between back of lens and retina, contains jelly-like substance
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6
Q

What do the anterior/posterior chambers of eye contain?

A

aqueoue humor

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7
Q

What is an example of aqueous humor disorder?

A

glaucoma [excess aqueous humor in eye from drainage obstruction and other causes]

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8
Q

What is the lens?

A

biconvex structure, refracts light to focus it on retina

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9
Q

What is blood supply to lens?

A

avascular

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10
Q

What suspends the lens? what happens to these over time?

A
  • zonules

- they weaken with advanced age which is what causes eye problems as you get older

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11
Q

What are two examples of lens disorders?

A

presbyopia

cataracts

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12
Q

what is presbyopia?

A

loss of ability of lens to change shape [focus between distance and near]

– occurs with age, lens hardens and less elastic

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13
Q

what are cataracts?

A

clouding/yellowing of lens with advanced age

- initially have mild disturbance of vision then progressive loss

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14
Q

What is glaucoma?

A

excess aqueous humor (over production, under drain)

causes increased pressure thus lead to optic nerve injury and decreased vision

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15
Q

What are clinical signs of glaucoma?

A
  • high IOP
  • cupping of optic nerve
  • peripheral visual field loss progressing inward
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16
Q

What are two types of glaucoma?

A
  • primary open angle

- closed angle

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17
Q

What is primary open angle glaucoma?

A
  • wide/open angle betwen iris and cornea
  • due to slow clogging of drainage canals of eye
  • asymptomatic early but can advance to irreversible vision loss
  • most common type in elderly
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18
Q

What is closed angle glaucoma?

A
  • less common
  • higher risk in asians, females, hyperopia
  • angle/drainage canal between iris + cornea closed or narrow
  • creates suddent rise in IOP –> need meds or laser surgery
  • signs: ocular pain, redness, N/V, headche, blurred vision, halos around light
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19
Q

What is age-related macular degeneration [ARMD]? risk factors?

A

ARMD = degenerative disease of macula/fovea –> get decreased central vision/blind spot

risk factors: age > 70, fair skin, family history, smoking, heart disease

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20
Q

What are the two types of ARMD?

A
  • wet and dry
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21
Q

What is dry ARMD? signs?

A
  • gradual visual loss due to formation of small yellow deposits under macula
  • early = asymptomatic, straight lines appear crooked, advanced = central blind spot
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22
Q

What are drusen?

A

small yellow deposits under macula, cause dry ARMD

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23
Q

What is wet ARMD?

A
  • sudden, severe visual loss due to growth of blood vessels + bleeding under retina

decrease risk: eat fruits/veggies

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24
Q

What is diabetic retinopathy?

A
  • increased blood glucose damages retinal capillaries –> breakdown blood retinal barrier
  • causes retinal ischemia
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25
Q

what are findings of diabetic retinopathy?

A
  • early = asymptomatic
  • may have microaneurysms, hard exudates, intraretinal hemmorrhage
  • cotton wool spots
  • retinal ischemia
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26
Q

what are the 3 clinical stages of diabetic retinopathy

A

non-proliferative: asymptomatic

pre-proliferative: give laser therapy to prevent long term vision loss

proliferative: major cause severe visual loss, need laser treat or surgery

27
Q

what is treatment for severe diabetic retinopathy? side effects?

A
  • kill off peripheral ganglion skills to prevent VEGF from forming
  • laser treatment (causes some loss of peripheral vision and decreased night vision)
28
Q

How does hyperglycemia affect eyes?

A

when blood glucose > 200, lens can swell in eye and lead to blurred vision

29
Q

How does retinal detachment present?

A
  • presents with: light flashes due to tugging of vitreous on retina, floaters, curtain over vision, can create whole in retina
  • usually have symptoms before retinal detachment
30
Q

What is a retinal infarct? signs?

A

central retinal artery occlusion
–> see retinal whitening/edema and cherry red spot in the middle

if not treated w/in 3 hrs –> permanent vision lost

31
Q

What is hollenhorst plaque?

A

thromboembolus in retinal arteriole

32
Q

what is retinitis pigmentosa? signs?

A
  • disorder of rods that involves progressive retinal degeneration due to pigmentary depositis
  • also see optic nerve atrophy
  • symptoms: nigh/low vision blindness, tunnel vision
  • slow process takes decade to happen
  • may be hereditary
33
Q

What is a roth spot? what 2 systemic diagnoses should you consider?

A
  • retinal hemorrhage with white center
  • infective endocarditis
  • leukemia
34
Q

What covers the optic nerve?

A

meninges! because its just an extension of the CNS

35
Q

What is optic neuritis? pathogenesis?

A
  • inflammatory optic neuropathy

- presumed to be due to demyelination

36
Q

What disease are associated with optic neuritis?

A
  • multiple sclerosis
  • sarcoidosis
  • neuromyelitis optica
  • infections
37
Q

Who gets optic neuritis?

A

usually under age 40

38
Q

What are symptoms of otpic neuritis?

A
  • acute onset: unilateral loss of visual acuity, color, field
  • pain on eye movement
  • may or may not have afferent pupillary defect [APD]
  • on exam: optic nerve head swollen or normal
  • visual loss worst days - 2 wks after onset, recover over wks - months
39
Q

24 yo comes in with blurry vision, one eye really hurts with movement?

A

think optic neuritis!

40
Q

What is treatment optic neuritis typically?

A
  • can resolve on its own after wks to months
  • to accelerate: give IV steroids
  • give MRI since there is an association with MS
41
Q

What is typical of MS on MRI of brain?

A

white matter periventricular lesions > 3mm in size

42
Q

What is risk of MS with optic neuritis?

A

22%

or 72% if any sort of periventricular white matter lesion

43
Q

What is papilledema?

A

optic disc edema/swelling caused by high intracranial pressure, usually bilateral

  • optic disc edema without ICP is not papilledema
44
Q

What are causes of bilateral optic disc edema?

A
  • papilledema
  • malignant hypertension
  • ischemia/inflamation, etc
45
Q

What are causes of papilledema?

A
  • intracranial mass [frontal lobe meningioma
  • hydrocephalus
  • pseudotumor cerebri
46
Q

What is mech of optic disc edema?

A

lack of axonal transport from build up of pressure greater than IOP –> get disc swelling

47
Q

What are symptoms of papilledema?

A
  • many nerve axons lost before any detectable visual field defect
  • once visual loss begins, rapidly progresses
  • get chronic to atrophic papilledema within 3 wks
48
Q

Which muscle contraction leads to miosis? which mydriasis?

A

sphinter = miosis [PNS]

dilator muscle = mydriasis [SNS]

49
Q

What is physiologic anisocoria?

A

unequal pupil size

50
Q

what is relative afferent pupillary defec [APD]t? test?

A
  • defect = if input from one eye is less than the other

- swinging flashlight test –> input from one eye is less than other eye

51
Q

causes of APD?

A
  • optic neuritis/glaucoma
  • chiasmal or optic tract lesion
  • severe retinal damage
  • amaurotic pupil

NOT: ocular media opacities [cataract] or amblyopia

52
Q

What is Holmes-Adie’s Tonic Pupil?

A
  • idiopathic

- one pupil abnormally large –> constricts poorly to light, due to palsy of iris sphincter muscle

53
Q

What is horner syndrome? signs?

A

oculosympathetic paralysis on one side
- could indicate dissection of carotid artery

signs:

  • ptosis and small pupil on one side
  • anhidrosis [decreased sweating] of the affected forehead
  • enesecoria worse in the dark [eye doesn’t dilate in the dark]
54
Q

who is at risk for glaucoma?

A
  • elderly
  • afica americans
  • people with elevated intraocular pressure
  • family history of glaucoma
55
Q

What should you think if pt presents with: gradual vision loss startig at periphery and progressing in?

A

glaucoma = tunnel vision

56
Q

What should you think it pt presents with: vision loss starting with central blind spot in elderly

A

age-related macular degenration [ARMD]

57
Q

What should you think: pt says straight lines appear crooked?

A

dry ARMD

58
Q

Is dry or wet ARMD more gradual?

A

dry!

59
Q

Should type 1 or type 2 diabetes have annual opthalmologic exams immediately after diagnosis?

A

type 2 because its likely they were undetected or had high blood glucose for a while

60
Q

What is leading cause of blindness in working age americans?

A

diabetic retinopathy

61
Q

What are argyll robertson pupils?

A
  • bilateral
  • dissociation of light-near reflexes
  • irregular pupils, accomodate [constrict in near] but don’t react [constrict in lihgt]
62
Q

What are some possible common causes of argyll robertson?

A
  • neurosyphilis

- diabetes

63
Q

What are signs of pupil defect associated with 3rd nerve palsy?

A
  • mydriasis [dilation]
  • ptosis
  • can’t react to light or near
64
Q

What is common cause of CN3 pupil lesion? why is pupil vulnerable?

A
  • fibers to pupil are external part of nerve = vulnerable to compression
  • common cause = aneurysm of posterior communicating artery (Pcom)