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BRB Final > EYES! > Flashcards

EYES! Flashcards

1
Q

Fnc of eyes

A
  • transmit light
  • refract light onto retina
  • transduce light > signal
  • process signal > CNS
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2
Q

Refractice power due to:

A

2/3 cornea - fixed

1/3 lens - variable. accomodation

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3
Q

Corneal layers

A 
5:
Epithelium
Bowman's layer
Strom
Descemet's membrane
Endothelium
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4
Q

Lens

A
  • capsule, epithelium, nucleus, cortex

- controled by ciliary muscles on zonules

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5
Q

Cataracts

symptoms:

A

-opacity of lens
-blindness
Types:
-cortical: see white lines, periphery
-nuclear sclerosis: aging - yellow
-posterior subcapsular - steroids, dm

Symptoms: blurr, glare, halows, yellowish, change eyeglsses

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6
Q

Uvea

A
  • iris, ciliary body, choroid
  • colour
  • vascular
  • muscle attachements
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7
Q

Iris

A

sphincter muscle constrict via parasymp and CN 3
dilator muscle dilates via symp, adrenergics
colour: few pigment = blue; lots = brown

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8
Q

Horner’s Syndrome

Types

A
  • ptosis
  • constricted pupils
  • anhyrodrosis

Types:
Central: 1st neuron - medullary lesions, hypothal, midbrain, cervical cord

Preganglionic: 2nd neuron - tumours, plexus issues, nerve root. look for facial anhydrosis

Postganglionic: 3rd order - ICA dissection, neck lesions, cavernous sinus

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9
Q

Ciliary body fnc

A
  1. produce aq humour > nourishes avascular cornea, lens (drained by trabecular meshwork > canal of Schlem > venous)
  2. accomodation: change lens shape via zonules p
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10
Q

What is glaucoma? Tx?

A

elevated intraocular pressure b/c obstruction of aq drainage
-can damage optic nerve

Tx: lower IOP

  • decrease production
  • increase flow
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11
Q

What is the near triad?

A
  1. Accomodation: ciliary body muscle contracts > relax zonules > lens ROUND > focus near
  2. Eyes converge - keep object on fovea
  3. Pupils constrict:
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12
Q

Vitreous Humour

A
  • 99% water, 1% collagen, hyloronic cid

- clear

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13
Q

Macula

A

Centre of retina
-most detailed vision, centre vision
Fovea is centre - avascular

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14
Q

Retinal layers

A
  • 10 layers
  • light goes through 8 cell layers + vessels> photoreceptors > ganglion cells > optic nerve
  • RPE: blood-retina barrier. supply photoreceptors
  • choroid is underneath
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15
Q

Choroid

A
  • vascular

- supplies outer retina

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16
Q

Optic nerve:

A

intraocular 1mm
intraorbital 25mm -behind globe
intracannalicular 9mm - skull
intracranial 16mm - brain

attached to dura in optic canal - common injury site

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17
Q

Orbit bones: roof, lat wall, floor, med

A

roof: frontal, lesser wing
lat: greater wing, zygomatic
floor: sygomatic, maxillary, palatine
med: maxillary, lacrimal, ethmoid, sphenoid

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18
Q

Eyelids

A

control by
LPS - CN 3
Muellers - sympathetic

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19
Q

Tear Film

A
  • keeps eye moisten and clear
    1. Mucin layer: produced by conjunctiva. tear adherence to cornea
    2. Aq layer: produced by accessory lacrimal gland. forms bulk
    3. lipid layer; produced by meibomian gland in lid mergin. reduce evaporation
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20
Q

Lacrimal system

A

upper outer orbit

  • reflex secretion
  • accessory glands
  • drain to nasolacrimal duct
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21
Q

EOMuscles adn actions

A 
LR: abduction
MR: adduction
SR: elevation
IR: depression
SO: incyclotorsion; depress abducted eye
IO: excyclotorsion; elevate abducted eye
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22
Q

Visual acuity

A

normal; 20 line at 20 ft
driving 20/50
legally blind 20/200.

if can't see chart:
20ft
10ft
counting fingers
waving hand
light perception
NLP
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23
Q

Light Convergence/Divergence: lens used

A

Concave lens increase divergence to see far

Plus lens converge light

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24
Q

What is emmetropia?

A

good vision - parallel rays for far objects. distance is in focus. use accomodation for near
don’t need correction

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25
Q

What is presbyopia?

A

insufficient accomodation for near object. Distance is focus. near bad.
-need plus readers or bifocals.

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26
Q

What is myopia?

A
  • nearsighted
  • distant light out of focus because eye too long - too much convergence.
  • need divergent glasses
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27
Q

What is hyperopia?

A

eye too short - light behind retina

  • need plus power for distance and near
  • near vision fails first
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28
Q

What is astignmatism

A
  • eye not round
  • no point focus > image is not sharp
  • need corretion
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29
Q

Monocular vs binocular fields?

A

monocular field is at teh 2 sides - far nasal retina

binocular is overlapping and in front

30
Q

Where does retina send signal to?

A
  1. Hypothalamus: suprachiasmatic nucleus - biological clock
  2. Thalamus: LGN > 1ry visual cortex for perception
  3. Midbrain; pretectal and edinger westphl nuclei > pupillary light reflex
31
Q

Visual loss - hor vs vert

A
  • field loss respecting horizontal midline = optic nerve/retina issue
  • field loss respecting vert midline = neurological lesion (chiasm or beyond) , usually both eyes
32
Q

How is visual field projected onto retina

A

-laterally inverted and upside down
-latearl > nasal retina (bigger)
-medial > temporal retina
(reference pt = fovea)

33
Q

Why is fovea highest in resolution?

A
  1. few layers, avascular, ganglion axons divert around fovea > light goes through easier
  2. mostly cones
  3. high ratio of ganglion cells: photoreceptors > small receptive fields. good localiztion. clear
34
Q

Cones vs rods

A

Cones: 3 photopigment

  • bright light
  • visual acuity
  • colour vision

Rods:

  • monochromatic
  • dim light
35
Q

What is age-related macular degen?

A
  • changes in RPE
  • Drusens form: accumulation of debris
  • blood under retina is toxic to photoreceptors
  • blindness
36
Q

Describe pathway from visual field > cortex

A

fields are laterally inverted and upside down on retina.
-info on nasal retina deccusate at chiasm; temporal stay ipsilateral [CORTEX and visual field CONTRALATERAL: Rt cortex sees left world; left cortex sees riht world]
>tract > thalamus > cortex

Superior field > inf retina > travels through temporal lobe via MYERS loop to visual cortex
inferior field > parietal lobe > visual cortex

37
Q

What causes chiasmal defects?

visual field loss?

A

-pituitary adenoma
-supresellar meningioma
-enurysm of internal carotid
> bitemporal hemianopia
> junction scotoma: loss in one eye, wedge shape in the otehr

38
Q

Where is the fovea represented in cortex how much?

A

Fovea is 1% of retina but 50% of axons and tracts.

posterior 1/2 of calcarine fissure

39
Q

Risk factors for cataracts

A 
aging
fhx
dm
trauma
inflammation
steroids
UV light : WEAR SUNGLASSES!
40
Q

Cataract surgery

when are there exception to waiting till worsen?

A
  • when lack of vision interere wth func
  • only intervention that helps
  • use ultrasound and laser to break and remove cataract

-babies, cataract causing glaucoma/iritis, in teh way of retinal tx

41
Q

Complications to catarct surgery

A

-infection, hemorrhage, retina detachment, glaucoma, macular edema, capsular opacification: cells proliferate behind capsule - use lasers to remove

42
Q

What is hte pupil?

A
  • opening in iris
  • light enters through
  • size control by iris muscles
43
Q

What are causes of pathologic anisocoria.

A
  • unequal pupils
  • > 1mm
  • shine light: pupils react diff, and diff size in dark vs light
  • dilation: Cn 3 palsy, glaucoma, dilating drops, trauma
  • constriction: horner’s syndrome, iritis, cholinergic drugs
44
Q

miosis vs mydriasis?

A

miosis = constricted pupils

mydriasis: dilated pupils

45
Q

Causes of RAPD

A

-no input - pupils dilate with flashlight
(lesions of optic nerve and tract)
Optic nerve disease: trauma, glioma, glaucoma, neuritis
Retinal disease: detachment, occlusions

46
Q

What does not cause RAPD?

A

-cataract
-corneal scar
-refractive errors
-vit hemorrhage
-cortical blindness
-func vision loss
(lesions after tract does not cause rapd)

47
Q

Diabetic retinopathy

NPDR vs PDR

A
  • inner BRB - tight jnc loss, pericyte loss, leak fluid and fat into retina
  • vision loss under 55 major cause

Nonproliferative: retinal vessel closure, alter perm
> see exudates, dot-blot hemorrhages, microaneuryms, macular edema is the most common cause of vision loss in NPDR (treat with laser)
-can lead to PDR

Proliferative: abnormal growth of tissue after ischemia
-VEGF signal new vessel growth on retina
> cause tractional retinal detachment, vitrous hemorrhage, neovascular glaucoma
(treat with laser)

48
Q

age-related macular degen
Wet vs Dry
Tx

A
  • outer BRB - break down barrier > swelling
  • degen the macula
  • damage centre vision whil peripheral ok

Wet ARMD:
-break RPE > blood into space

Dry ARMD: more common

  • Drusen deposits: Ca deposits
  • pigmentation abnormalities

TX: anti VEGF injections

49
Q

Blood retina barrier

A

made up by retinal vessels and RPE

-dual supply:
inner 2/3: retina vessels. tight jncs, no leak. pericytes 1:1
outer 1/3: choroid

50
Q

How to check for optic nerve fnc

A 
visual acuity
RAPD
visual fields
color vision
contrast sensitivity
51
Q

How much of axons deccusate at chiasm?

A

53% deccusate

47% ipsilateral

52
Q

How to evaluate optic nerve: BCC

A

Borders: sharp rim
Cup: inside bright part. 30% of disc. part of nerve without living things.
Color: pink. no hemorrhage

53
Q

What is papilledema?

A
  • swelling of nerve due to increased ICP!
  • CSF push on nerves
  • bilateral
  • vision normal unless severe
  • MRI, LP
54
Q

Common optic neuropathies?

A

under 50; demylination > optic neuritis: unilateral visul loss, RPD, pain on movement, may see swelling
-check for MS

over 50: non-areritic ischemia

  • hypopersuion of optic nerve
  • wake up with visual loss, respect horiz midline.
55
Q

What is arteritic optic neuropathy

A

ex: Giant cell arteritis
-over 70yrs
-jaw claudications, headache, wt loss, fever, shoulder pain
-inflammation of vessels > occlude > ischemia
-visual loss in 1 eye, irreversible
-check inflammation makers!
TX: steroids

56
Q

What are the eye movemetns? 6

A 
Keep eyes still when head moves:
1. vestibuloocular reflex
2. optokinetic reflex
Change looking
3. saccades
Keep object on fovea
4. Pursuit
5. Fixation
Change plane of object
6. vergence
57
Q

Brainstem parts involved in vision

A
  • midbrain: vertical gaze (riMLF)
  • pons: hor gaze (Ppontine reticular formation)
  • medulla: control
58
Q

Describe teh vestibuloocular reflex

A

quick reflex
-semicircular canal detect head motion in X direction
> contralateral CN 6
> contralateral LRectus contract to move in opposite side of X
> ipsilatearal CN 3 > MRectus

Indirect pathway involving Nucleus prepositus hypoglossi to keep eyes from getting pulled back when head moves during horizontal eye movements
-interstitial of cajal during veritcl eye movements

-inhibited by antibiotics: aminoglycosides

59
Q

Describe optokinetic reflex

A
  • moving stimulus, keep eyes straight

- slow pursuit + saccades

60
Q

Pathwy of saccades

A

-stimulus enters > position info from visual cortex > Parietal Eye Field > Prefrontal cortex for planning of saccades > Frontal Eye Field to execute motor pathway

> internal capsule > Superior colliculus > deccusate on contralateral PPRFormation in pons > CN 6 N
contra CN 6 LR constrict
goes to MLF deccusates on CN 3 N > ipsilateral MR constricts

61
Q

Pathway of smooth pursuit

A

-visual cortex gives velocity info to parietal. similar pathway to saccades
but invoves cerebellum before going to CN 6 N

62
Q

Predict eye deviation with these lesions:

  1. Right temporal lobe
  2. Pontine midline
  3. Right MLF (brainstem)
A
  1. right gaze - away from hemiporesis
  2. left gaze - toward hemiporeis
  3. left gaze -toward hemiporesis
63
Q

Monocular diplopia
Cause
Tx

A
  • due to eye abnormaly or glasses
  • resolves with pinhole

Causes: refractive errors

  • lid lesion
  • dry eyes, scr, cataract, lens issus, wrinkled retina, uveitis

Tx: glasss, drops, surgery

64
Q

Binocular diplopia

TX

A
  • due to ocular misalignment: check with coreneal light reflex - ESOtropia - eye in; EXOtropia: out
  • due to mechanical (orbit fractures, graves) vs innervational (stroke, palsies, MG)
  • double worse in direction of weakness
  • tilting head to opposte direction
  • ptosis

Tx; patch (monovision), prism glasses, treat underlying, if 6mo and still: imaging, strabismus surgery, botox weakens muscle

65
Q

What is teh 3 step test?

A
  • CN 4 palsy
  • look straight : hypertropic eye
  • side gaze: double vision worse in oppostive direction of palsy
  • tilt head to shoulder: double vision worse on side of palsy (that’s why they tilt to the other side)
66
Q

CN 6 palsy

A

-horizontal
-esotrophic
trauma, ischemia, dm
-look for papilloedema

67
Q

CN 4 palsy

A
  • hypertropia
  • vertical/diagonal
  • head tilts oppos side
  • trauma, congenital, ischemia
  • usually not tmour/aneurysm
68
Q

CN 3 palsy

A

-eye down and out (hypotropic and exotrpic)
-ptosis
check PUPIL - may be dilated > surgical needed may be Pcomm aneurysm
-diagonal or none if there’s ptosis
-ischemia, aneurysm (pupils involved), trauma

69
Q

What is INO

A

internuclear ophthlmoplegia

  • lesion to MLF > ipsilateral adduction defecit (not MRectus issue)
  • may see nystagmus
  • horizontal diplopia

young: think MS
old: think stroke

70
Q

What is strabismus surgery

A
  • Recess: cut back the antag muscle - weaken

- Resect: strengthen the lesioned muscle

BRB Final (8 decks)

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