Lectures 25-27: Eye Flashcards Preview

Brain and Behavior > Lectures 25-27: Eye > Flashcards

Flashcards in Lectures 25-27: Eye Deck (121):
1

Elevation mediated by...

Sup rectus and inf oblique

2

Depression mediated by...

Inf rectus and sup oblique

3

Pulling directions of eye muscles are in same plane as...

Semicircular canals

4

Torsional eye movements: which muscle groups control which directions?

When eye is abducted, the oblique muscles control torsion; when eye is adducted, the rectus muscles control torsion

5

Torsion (definintion)

Rotating eye movement within the globe

6

Two causes of IIIrd nerve palsy

Uncal herniation or PCOM aneurysm

7

Describe IIIrd nerve palsy

Impaired elevation, depression and adduction (Down and Out); ptosis; enlarged pupil

8

IVth nerve palsy

Gaze of affected eye is up and medial w/ head tilt to unaffected side

9

VIth nerve palsy

Gaze of affected eye cannot abduct

10

Where does binocular coordination occur in LMNs?

Fiber connections in medial longitudinal fasiculus (MLF)

11

MLF interconnects...

The vestibular nuclei, VI, IV, and III

12

Lesion of abducens nerve

Impaired abduction of ipsilateral eye

13

Lesion of abducens nucleus or PPRF also...

Destroys internuclear neurons (which cross and ascend to medial rectus motor neurons in oculomotor nucleus via MLF) --> ipsilateral lateral gaze palsy (inability of patient to look to side of lesion with EITHER eye)

14

Lesion of MLF...

Internuclear opthalmoplegia (INO) (ipsilateral eye cannot adduct, contralateral nystagmus [because brainstem is attempting to maintain conjugate gaze])

15

Paramedian pontine reticular formation (PPRF)

Receives connections from contralateral frontal eye fields and innervates abducens nucleus (so, causes same effect as damage of abducens)

16

What disease often impacts MLF? Talk about age/diagnosis

MS: 1/3 of cases of INO are attributable to MS; 45 yo = unilateral, stroke

17

Locations of cortical and subcortical control eye movement mechanisms

Cortical eye fields: frontal (supplemental eye field and frontal eye field), parietal (parietal and parieto-occipital eye fields); Subcotical regions: superior colliculus, pretectum, RF

18

Saccadic eye movements (definition and description). For all saccades, cortical outflow is directed to neurons in the...

Conjugate eye movements intended to foveate a point of interest, fast and ballistic; superior colliculus

19

How to make a horizontal saccadic eye movement?

PPRF --> abducens --> MLF pathway we learned before PLUS reciprocal inhibitory projections arising from the other abducens nucleus

20

What is the saccadic gaze center for vertical eye movements? What muscles/nerves?

Rostral interstitial nucleus of the MLF (riMLF); IV and III: io, sr, ir

21

Smooth pursuit eye movements (definition and stimulus)

Slow conjugate eye movements used to maintain stable retinal image, stimulus is retinal slip

22

Pathway for smooth pursuit involves...(network name)

Cortico-ponto-cerebellar network

23

Optokineti nystagmus (phases)

Slow component: smooth pursuit (large moving visual targets); Fast component: saccadic eye movement (reflexively resets the eye; DIRECTION NAMED FOR THIS PHASE)

24

Vestibulo-ocular reflex (VOR) (definition and neuron arc)

A compensatory eye movement that maintains visual fixation during head movements; head rotation to the right --> activates the right horizontal canal and inhibits the left horizonal canal --> conjugate gaze to the left (involves excitatory [contralateral to activated canal] and inhibitory [ipsilateral to activated canal] pathway of abducens nucleus)

25

Caloric testing (theory and pneumonic)

Assesses cerebral cortex and brainstem function in unconscious patients, solution different from body temperature will set up convection currents in the fluid w/in the ear, the horizontal (lateral) semicircular canal is tested, then record eye movements; COWS: cold opposite, warm same

26

Caloric testing (colder)

Cold saline in left ear, nystagmus is to the right (opposite direction of the ear)

27

Caloric testing (warmer)

Warm saline in left ear, nystagmus is to the left (same direction of ear)

28

Vergence eye movements (definition, function, what your eye does)

Disconjugate eye movements; maintains fused fixation of a target as viewing distance changes; accommodation and miosis

29

What fibers interconnect the ciliary muscles and iris muscles?

Zonule fibers

30

Cornea responsible for how much refraction? And what structure does the remaining fraction?

2/3; lens

31

Describe the eye chambers

Anterior chamber: b/t cornea and lens filled w/ aqueous humor; Posterior chamber: between zonule fibers and ciliary body, aqueous humor made here by ciliary body; Vitreous body: between retina and lens, filled with vitreous humor

32

Bipolar cells

Link photoreceptors with retinal ganglion cells

33

Ganglion cells

First neuron cell in chain of light transduction

34

Horizontal cells

Horizontal interactions b/t photoreceptor cells (processes in outer plexiform layer)

35

Amacrine cells

Horizontal interactions b/t ganglion cells (processes in inner plexiform layer)

36

Layers of retina (10) and locations of cell bodies

Pigment epithelium, next three layers: photoreceptor cells (outer segment, inner segment, outer nuclear layer [cell bodies]), outer plexiform layer, inner nuclear layer (cell bodies of horizontal cells, bipolar cells, amacrine cells), inner plexiform layer, ganglion cell layer, optic fiber layer, internal limiting membrane

37

Rods

Detect light: low spatial resolution, night/peripheral vision

38

Cones (and the types w/ colors)

Detect color/acuity: high spatial resolution, day/foveal vision; L = red, M = green, S = blue

39

Relate convergence to acuity

HIGH degree of convergence of rods and rod bipolar cells onto retinal ganglion cells; LOW degree of convergence of cones and cone bipolar cells onto retinal ganglion

40

Fovea

Retinal layers become thinner at fovea, reducing barriers to light passage, cone-only region

41

What's cool about the structure of the optic nerve?

It's CNS, so it's covered with dura right up to the retina w/ central retina vessels running through

42

Blind spot is located in the _________ portion of the visual field

Temporal

43

Binocular visual field (definition) is flanked by the ________ _________

Area of the world seen by both eyes; monocular crescents

44

What happens at the optic chiasm? Which ones cross? So what happens?

Some of the fibers of the optic nerve cross; nasal retinal fibers (NOT temporal retinal fibers); right optic tract carries left visual field, left optic tract carries right visual field

45

Cut optic nerve...

Monocular blindness

46

Damage optic chiasm (in saggital plane)...why?

BiTEMPORAL hemianopia (while the nasal retinal fibers are cut, they carry the temporal visual field)

47

Where does optic tract travel to? How many cell layers and information? Does mixing of information from different eyes happen?

Lateral geniculate nucleus; 6; parvocellular layers (4) = cones, magoncellular layers (2) = rods; NO

48

Cut optic tract or LGN...

Homonymous hemianopia

49

What visual field quadrant is carried by Meyer's loops? Damage (optic radiations temporal lobe)?

Upper quadrant = homonynous superior quadrant hemianopia

50

Cut optic radiations (parietal lobe)

Homonymous inferior quadrant hemianopia

51

Superior visual field where in respect to calcarine fissure?

Inferior

52

Foveal vision maps to where in respect to occipital cortex?

Occipital pole

53

Damage to primary visual cortex...

Homonymous hemianopia

54

Damage to primary visual cortex further back...Why?

Homonymous hemianopia with macular sparing; due to magnificant factor (must damage a lot of occipital pole) and to blood supply

55

What two muscles control pupillary light reflexes and function

Sphincter pupillae: constricts, para; Dilator pupillae: widens, sympa

56

Steps of direct pupillary light reflex

Afferent: 1. Light to eye; 2. Optic nerve, chiasm, tract; 3. Midbrain pretectum. Efferent: 4. Edinger-Westphal nucleus, 5. CN III to ciliary ganglion; 6. IPSILATERAL sphincter muscle contracts

57

Steps of consensual pupillary light reflex

Afferent: 1. Light to eye; 2. Optic nerve, chiasm, tract; 3. Midbrain pretectum. Efferent: 4. CONTRALTERAL Edinger-Westphal nucleus via posterior commissure, 5. CN III to ciliary ganglion; 6. CONTRALTERAL sphincter muscle contracts

58

What cells project to which brain structures (3) to control light-dependent biological clock. Name function of each structure.

Photosensitive retinal ganglion cells project to the hypothalamus (suprachiasmatic nucleus = circadian rhythm), pineal gland = melatonin, and pretectal nucleus = pupillary light reflexes

59

What determines absorption in eye

Length of time drug stays in cul-de-sac

60

What are the two themes of distribution for the eye?

Systemic distribution: via nasal mucosa; Ocular distribution: via transcorneal/transconjunctival route

61

What determines eye metabolism? What does the metabolism?

Tear and tissue proteins, diffusion across cornea/conjunctiva; enzymes in eye and hepatic

62

Elimination in the eye

Nasolacrimal drainage --> bloodstream --> liver (note: avoids first pass metabolism that you have for oral meds)

63

Miosis

Constriction of pupils

64

Mydriasis

Dilation of pupils

65

Describe iris muscles

Sphincter/inner circular muscle = para; Outer radial muscle = sympa

66

What characterizes glaucoma

Elevated intraocular pressure (presses backward damaging optic nerve --> progressive retinal ganglion cell axon loss)

67

Types of glaucoma and presentation. What makes the angle?

Open-angle glaucoma (allows aqueous humor to circulate that is usually found on exam) and closed-angle glaucoma (emergency, no fluid can circulate to cornea, major increase in intraocular pressure that presents with pain, acute visual loss, erythema/edema); lens and iris makes angle

68

How do we treat closed angle glaucoma?

Lasor irodotomy: drills hole between iris and ciliary body to allow for drainage

69

Glaucoma is diagnosed with...(3)

Fundoscopic exam: cupping (enlarged, hollowed out appearance of optic nerve), visual field testing, intraocular pressure

70

Ciliary body consists of...

Ciliary muscles (2) and ciliary epithelium

71

Accommodation is mediated by __________ stimulation causing which muscle to contract? Define cyclospasm and cycloplegia

Parasympathetic; ciliary muscle; cyclospasm = severe muscle contraction and cycloplegia = no accommodation

72

What allows the aqueous humor to flow out? (2 methods)

1. Para stimulation --> tension of trabecular meshwork --> opening of pres allowing flow through Canal of Schlemm and trabecular meshwork; 2. Uveoscleral outflow pathway: aqueous humor can also flow through ciliary muscles into suprachoroidal space

73

What promotes aqueous humor secretion

Sympathetic stimulation via beta receptors

74

How to treat glaucoma?

1. Increase outflow (uveoscleral/canal of Schlemm) or 2. Decrease production

75

What is the first line therapy (example) for treatment of glaucoma, SEs.

Prostaglandin agonists (Latanoprost) which increase aqueous humor outflow via uveoscleral pathway; SEs: blurred vision, irritation, iris color change, keratitis

76

What receptor antagonist can be used to treat glaucoma (example)? Mechanism, SEs and special considerations (2)

Beta receptor antagonist (Timolol); decrease aqueous humor production; SEs: eye-related AND cardiovascular (bradycardia, hypotension), respiratory (cough, dyspnea); don't give to patients w/ respiratory disease and CYP2D6 metabolism

77

What receptor agonist can be used to treat glaucoma (example)? Mechanism, SEs

Alpha2 agonist (Brimonidine); decrease aqueous humor production via pre (less NE) and post synaptic (less cAMP) alpha2 receptors; SEs: eye-related AND cardio: hypotension

78

Carbonic anhydrase inhibitors example? Mechanism, SEs

Dorzolamide; HCO3- is secreted from blood into aqueous humor, inhibited by CA inhibitor, decreasing aqueous humor production, SEs: eye-related AND metabolic acidosis via CA inhibition in the kidney (HCO3- in lumen not changed into CO2, H2O to be reabsorbed)

79

Cholinergic agonist: 2 examples? Mechanism, SEs

Carbachol, Pilocarpine; muscarinic agonist: ciliary muscle contraction helps outflow; SEs: eye-related

80

Name two corneal disorders

Corneal abrasion (visualized with flourescent dye) and corneal ulcer (infection from an abrasion)

81

What is presbyopia?

Loss of accomodation of the eye due to weakening of the zonules.

82

A cataract is the most common disorder of the...what happens?

Lens; becomes cloudy and obstruct vision

83

During cataract surgery, what is put in the eye?

Intraocular lens (lens implant)

84

What is the second most common cause of visual loss in elderly?

Glaucoma

85

What is glaucoma?

Optic nerve damage associated with visual field defects usally associated with high intraocular pressure

86

What kind of vision loss happens with glaucoma?

Loss of peripheral vision

87

Glaucoma risk factors (6)

Elderly, African/Hispanic Americans, elevated with IOP, family history, diabetics, high myopia

88

What to check for when looking for glaucoma (3)

Eye pressure, visual field test, optic nerve damage

89

How do we test for optic nerve damage?

Enlarged cup in optic disc

90

Treatment for open angle glaucoma

Medications

91

Treatment for closed angle glaucoma and risk groups

Laser iridotomy; small eyes: Asians, females

92

What is the most common cause of elderly visual loss?

Age-related macular degeneration

93

What kind of vision loss happens with ARMD?

Central vision loss

94

ARMD risk factors (5)

Advanced age, fair skin/eyes, family history, smoking and heart disease

95

What causes dry ARMD?

Yellow deposits scattered throughout retina with gradual visual loss

96

What is the difference between dry and wet ARMD?

Fluid/bleeding beneath retina with sudden loss of vision; permanent damage

97

T/F: Diet has been shown to prevent ARMD

True! A diet rich in fruit and vegetables

98

Diabetic retinopathy is the __th leading cause of blindness in elderly Americans. How about working-age Americans?

4th; leading cause

99

What kind of vision loss happens with diabetic retinopathy?

Blurry vision with missing patches

100

T/F: Diabetic retinopathy cannot be prevented

False! Important for patient to work with doctors to screen for diabetic retinopathy

101

Increased blood glucose damages what in the eye?

Retinal capillaries

102

What are four pathological fundoscopic finding in diabetic retinopathy?

Microaneurysms (like little red dots), hemorrhages, cotton wool spots (ischemia), and hard exudates (later stage)

103

Three stages of diabetic retinopathy

Non-proliferative, pre-proliferatie, proliferative (neovascularization that causes vision loss)

104

What causes neovascularizastion? What is the reatment?

VEGF, lazer damaging of retina to regress neovascularization

105

Where does the optic nerve become myelinated? Is it covered by meninges?

After it exits the optic disc; yes

106

What is optic neuritis (ON)? Pathogenesis

Inflammation of the optic nerve; demyelination of nerve

107

If optic neuritis occurs alone it's called ________

Idiopathic

108

What is the most common optic neuritis association? What are some others (2)

MS (first clinical sign); sarcoidosis and infections

109

Symptom onset of ON and symptoms (4). Recovery?

Acute, loss of visual acuity, color, field and afferent pupillary defect; vast majority

110

T/F: ON always presents with a swollen nerve

False! Hard to detect with a fundoscopic exam

111

If someone has ON, what should be done?

Get an MRI to assess for MS

112

What is the difference between bilateral optic disc edema (two swollen discs) and papilledema?

Papilledema requires increased ICP (so, not all bilateral disc edemas cause papilledema)

113

What should you do if you find papilledema?

Scan them!

114

Reflexes of sphincter muscle

Light and near reflex

115

Difference in pupil size called? Can be...

Anisocoria; pathologic and physiologic

116

If one eye sees less light than the other, this is called...

Relative Afferent Pupillary Defect (RAPD)

117

RAPD can be caused by...(4)

Optic neuropathy, chiasmal/tract lesion, retinal damage, blindness

118

What is (Holmes-Adie) Tonic Pupil? Who tends to get this and how does it present? What is damaged?

Idiopathic disorder where one pupil (the abnormal one) is larger and reacts poorly to light/accommodation; young women often complain of difficulty reading; parasympathetic fibers to pupil

119

Argyll Robertson Pupils and number one and two cause

Miotic pupils w/ absence of pupillary light response but retention of near response; neurosyphilis and diabetes

120

IIIrd nerve palsy tends to effect which fibers first? What does this look like? What can cause this?

Pupillary fibers; affected pupil is mydriatic; uncal herniation/PCOM aneurysm

121

What is Horner syndrome? It causes...

Oculosympathetic paralysis; miosis of affected pupil and ptosis

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