Module 5: Visual Pathway Flashcards Preview

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Flashcards in Module 5: Visual Pathway Deck (70)
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0
Q

Examination of visual system

A

Visual acuity, Visual field, Pupillary light reflex, Extraocular muscles & Fundoscopy “VV PEF”

1
Q

Anatomy of the visual pathway

A

Eye-optic nerve-chiasm-optic tract-lateral geniculate-optic radiation-occipital

2
Q

To assess for macular degeneration

A

Retina

3
Q

The optic nerve: etiology of dysfunction

A

Compression, inflammation, Infarction & Alterations in blood supply “CIAA”

4
Q

Decussation of visual and pupil fibers. Multiple neighboring influences: ______, ______, ______ & ______.

A

Optic chiasm. CSF, Vascular, Skull & Pituitary.

5
Q

In __________, the defects become homonymous, on the same side as the visual space. A ___________ localizes only to the retrochiasmal area.

A

Retrochiasmal lesions. Complete homonymous hemianopsia.

6
Q

In retrochiasmal lesions, ________ are identical in size, shape and depth: applies only to _________. Imply a more _______: cortical anatomy.

A

Congruous lesions. Incomplete hemianopsia. Posterior lesion.

7
Q

Lesion in congruous homonymous hemianopsia

A

Optic radiation

8
Q

Lesion in incongruous homonymous hemianopsia

A

Optic tract

9
Q

Retrochiasmal field defects: occipital lobe

A

Homonymous quadrant, Temporal crescent & Macular sparing “HTM”

10
Q

Retrochiasmal field defects: lateral geniculate

A

Homonymous sectoranopia

11
Q

Retrochiasmal field defects: temporal lobe

A

Homonymous “pie in the sky”

12
Q

Carry fibers to the LGB. Carry pupil fibers to the midbrain enlage of _________ via the brachium of the superior colliculus. ________ field defects.

A

Edinger Westphal. Incongruous.

13
Q

Located in the posterolateral thalamus. Retinotopic organization: layer _____ from contralateral eye. Layer ____ from ipsilateral eye. The _____ projects to 50% of the LGB.

A

Lateral geniculate. 1, 4 & 6. 2, 3 & 5. Fovea.

14
Q

Meyer’s loop: temporal lobe. Parietal lobe path direct. Majority of fibers from other thalamic nuclei.

A

Optic radiations

15
Q

Striate cortex V1. Caudal 50% encode central __ degrees. Middle 40% encodes ___ degrees. Rostral 10% encodes __ degrees. (The temporal crescent)

A

Occipital cortex. 10. 10-60. 60-90.

16
Q

The where pathway

A

Occipitoparietal

17
Q

The what pathway

A

Occipitotemporal

18
Q

Testing techniques

A

Confrontation, Patient drawing & Bowl perimetry “CPB”

19
Q

Bowl perimetry. Kinetic: ________.

A

Goldman perimeter

20
Q

Bowl perimetry. Static: ________.

A

Humphrey perimeter

21
Q

May occur unilateral or bilateral. Poor vision with small nerve. May occur in isolation or with ocular or forebrain abnormalities. When bilateral and accompanied by poor vision and nystagmus, usually other developmental abnormalities observed.

A

Optic nerve hypoplasia

22
Q

Disturbance of axonal metabolism in the presence of a small scleral canal. Increase in size with time, more visible with time due to calcium deposition. Associated visual defect at times not noticed by the patients.

A

Optic disc drunsen

23
Q

Possible association with increased abuse of alcohol and drugs. Phenytoin, quinine, alcohol, LSD and cocaine. Maternal diabetes. Perimetry: irregular borders, stable overtime.

A

Optic nerve hypoplasia

24
Q

Central cup absent, anomalous vascular branching, vessels arising from the apex of the nerve, retention of vascular detail. Transillumination and irregular disc margin. No hemorrhage or cotton wool spots.

A

Disc drunsen (ophthalmoscope)

25
Q

Causes are protean. Papilledema: elevated ICP and disc edema. Space occupying lesion. Disruption of axoplasmic flow at the level of the lamina cribrosa: fast and slow. Subsequent hypoxia and vascular changes on the disc. May take hours to resolve.

A

Swollen optic nerve

26
Q

Elevated ICP: headache,nausea,TOV & tinnitus. Normal neurologic exam. Elevated CSF pressure with normal parameters & normal imaging to exclude mass lesion or dural sinus thrombosis. Transient obscurations of vision. Neck stiffness. Neck, shoulder or arm pain. Diplopia (CN VI palsy)

A

Idiopathic intracranial hypertension

27
Q

Acquired optic nerve disease without disc edema. Painless progressive loss of vision over first week. Predominantly monocular. Preceding viral illness & sinus symptoms. Loss of acuity, abnormal visual field, color vision & afferent pupil defect.

A

Optic neuritis

28
Q

Most common cause for disc swelling over age of 50.

A

Ischemic optic neuropathy.

29
Q

Brings the target to the fovea

A

Saccades

30
Q

Looking from far to near

A

Vergence

31
Q

Moving objects are kept still on retina

A

Pursuit

32
Q

When we move our head eyes stay locked on target

A

Vestibular ocular reflex

33
Q

When image slips on a large portion of the retina

A

Optokinetic reflex

34
Q

Adduction

A

Medial rectus

35
Q

Elevation & small intorsion

A

Superior rectus

36
Q

Intorsion & small depression

A

Superior oblique

37
Q

Abduction

A

Lateral rectus

38
Q

Depression & small extorsion

A

Inferior rectus

39
Q

Extorsion & small elevation

A

Inferior oblique

40
Q

Along the medial aspect of the eyeball, inserts at a point of 5.5mm of the limbus. It is controlled by oculomotor nerve. Contraction of this muscle causes adduction of the eye.

A

Medial rectus

41
Q

Along the inferior aspect of the eyeball, inserts at a point of 6.5mm of the limbus. It is controlled by oculomotor nerve. When the eyeball is positioned 23 degrees ouward in the orbit with respect to primary gaze, contraction of this muscle causes depression of the eye. When the eyeball is postioned 67 degrees inward, causes excycloduction of the eye.

A

Inferior rectus

42
Q

Contraction causes depression, excycloduction & adduction of eye

A

Inferior rectus

43
Q

Along the lateral aspect of the eyeball, inserts at a point of 7mm of the limbus. It is controlled by abducens nerve. Contraction of this muscle causes abduction of the eye.

A

Lateral rectus

44
Q

Along the superior aspect of the eyeball, inserts at a point of 7.5mm of the limbus. It is controlled by oculomotor nerve. Contraction of this muscle causes elevation, incycloduction & adduction of the eye.

A

Superior rectus

45
Q

Passes through the trochlea and its insertion on the eyeball below the superior rectus muscle is at 51degrees with respect to primary gaze. Controlled by trochlear nerve. Contraction of this muscle causes incycloduction, depression and abduction of the eye.

A

Superior oblique

46
Q

The insertion of the is on the eyeball below the lateral rectus muscle at 51degrees with respect to primary gaze. It is controlled by oculomotor nerve. Contraction of this muscle causes excycloduction, elevation and abduction of the eye.

A

Inferior oblique

47
Q

Describes movement of one eye

A

Duction

48
Q

Describes movement of two eyes in the same direction

A

Version

49
Q

Describes movement of two eyes in opposite direction

A

Vergence

50
Q

Point of intersection of line of sight when eyes are maximally converged. Theoretically, should be measured from center of rotation of eyes. Clinically, measured from the facial plane.

A

Near point of convergence

51
Q

Maximun convergence ability or NPC is measured by

A

Confrontational testing

52
Q

NPC breakpoint, target becomes double.

A

Greater than 7cm

53
Q

Average NPC

A

5cm

54
Q

The recovery point, target becomes single.

A

10cm

55
Q

Fast, step-like eye movement that places image of the target on the fovea.

A

Saccade

56
Q

Slow, smooth-following movement that maintains image of the target of fovea

A

Pursuit

57
Q

The most common test for extraocular motility

A

Broad H test

58
Q

Is also a part of confrontational testing

A

EOM testing

59
Q

To investigate the integrity of EO muscles and their nerves. To assess the patient’s ability to perform version eye movements. And to determine if strabismus is comitant.

A

Extraocular motility testing

60
Q

A pursuit test done bonocularly with penlight at a test distance of 30-40cm. It tests 9 position of action, starting with primary position. It tests fields of action of the 6 extraocular muscles.

A

Broad H test

61
Q

Direction where a particular muscle has the greatest action

A

Field of action

62
Q

Look for lags or overshoots at various diagnostic position of gaze. Look for smooth and accurate pursuit movements. Look for any gaze restrictions or overactions of muscle in 9 position.

A

Broad H Test

63
Q

When deviation of the visual axes remains constant in all fields of gaze, there is

A

Comitancy

64
Q

When deviation of the visual axes changes with field of gaze, there is

A

Noncomitancy

65
Q

Check by moving the target to diff. positions of gaze, while keeping the patient steady.

A

Comitancy

66
Q

Expected findings for saccade testing

A

Smooth, Accurate, Full & Extensive. “SAFE”

67
Q

Drugs, fatigue, basal ganglia syndromes, cerebellar syndromes, peripheral oculomotor weakness, white matter diseases and miscellaneous disorders.

A

Slow saccades

68
Q

Calibration errors. Opsoclonus. Restriction syndromes.

A

Fast saccades

69
Q

Ocular restriction syndromes. Cranial nerve, muscle palsies. Nuclear lesions.

A

Assymetrical saccidic velocity