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Neuroscience BB Exam 2 > Visual System Anatomy / Physiology > Flashcards

Visual System Anatomy / Physiology Flashcards

1
Q

What is uveitis?

A

Inflammation of iris, ciliary body, and choroid (often secondary to eye injury)

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2
Q

What is presbyopia?

A

Loss of lens resilience (lens gets flatter as we get older) with age so that accommodation gets worse. The nearpoint recedes - can’t focus on close things. Get bifocals (like Carly at age 5) or reading glasses.

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3
Q

What are cataracts?

A

Growth of the concentric layers of fibrous cells in the lens over time (with no turnover of protein) leads to cloudy and opaque appearance from denaturation of cross-linking of proteins. (Other causes: UV light, diabetes, aging)

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4
Q

What are congenital cataracts?

A

A real drag - danger for complete loss of vision within affected eye; like from rubella in development

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5
Q

What is a homonymous defect?

A

Visual defect in SAME region for BOTH eyes (lesion to optic tract, both ipsilateral optic radiations, or ipsilateral lingual and cuneus cortex

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6
Q

A lesion to the lingual cortex and cuneus cortex from vessel occlusion can still have _______ from collateral MCA perfusion to the caudal visual cortex.

A

macular sparing

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7
Q

What is a contralateral homonymous hemianopsia?

A

From occlusion of anterior choroidal a. leading to ischemia of optic tract. Deficits in same part of visual field in each eye, in part of visual field opposite the side of the lesion.

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8
Q

What is ipsilateral nasal hemianopsia?

A

Lesion of lateral optic chiasm - nasal visual field, same side (only one eye)

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9
Q

What is bitemporal hemianopsia?

A

Lesion at optic chiasm (like pituitary tumor) resulting in loss of visual field input from BOTH temporal halves

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10
Q

What is papilledema?

A

Swelling of optic disc as a result of increased intracranial pressure (subarachnoid space extends along the nerve) around the optic nerve, impeding venous return –> partial/complete loss of vision

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11
Q

What is blindsight?

A

Ability for those with striate (primary visual) cortex lesions (cortically blind) to respond to visual stimuli that are not consciously perceived. Object orientation and tracking with eyes/head.

Retina –> superior colliculus –> pulvinar –> posterior parietal cortex (orientation and tracking)

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12
Q

What is achromatopsia? What pathway does it affect?

A

Can’t perceive colors, but can perceive object. Result of lesion to ventral stream (the “what” pathway, parvocellular), for recognition of objects, perception of color, shape, and textures (V4)

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13
Q

What is akinetopsia?

A

Can’t perceive motion, but can perceive stationary objects. Result of lesion to dorsal stream V5 (the “where” pathway, magnocellular), for processing of motion, speed, direction (increasing complexity further from calcarine sulcus).

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14
Q

What is prosopagnosia?

A

Inability to interpret, remember, recall formed images (like faces). From lesion of lateral fusiform gyrus (usually right side) or occlusion of PCA.

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15
Q

What is detachment of the retina?

A

Pigment cell layer detaches from neural layer (opens obliterated intraretinal space from the optic cup) from seepage of fluid between layers after trauma. Patient sees flashes of light or specks floating in front of the eye.

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16
Q

What is anophthalmia?

A

Congenital absence of all tissues in the eye; eyelids form but no eyeball. Primary is failure of optic vesicle to form. Secondary is from depressed forebrain development (missing eye is associated).

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17
Q

What is microphthalmia?

A

Miniature eye; arrested development of eye before optic vesicle has formed, lens doesn’t form.

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18
Q

What is coloboma of the retina?

A

Localized gap in retina, usually inferior to optic disc, from defective closure of retinal fissure

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19
Q

What is cyclopia?

A

Eyes fused in single median eye, tubular nose superior to eye (proboscis). Cyclopia is the single eye, and synophthalmia is fused eyes.

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20
Q

Holoprosencephaly is severe suppression of midline cerebral structures that produces _____

A

cyclopia

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21
Q

What can happen with a persisting hyaloid artery?

A

Proximal is the central artery of the retina. If the distal persists, it appears as a free-moving, wormlike projection from optic disc. Can form a cyst.

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22
Q

What is congenital glaucoma?

A

Abnormal development of scleral venous sinus of aqueous humor increases intraocular pressure.

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23
Q

Congenital ptosis results from:

A

failure of development of levator palpebrae superioris (injury/dystrophy of superior division of oculomotor n.)

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24
Q

Direct light reflex:

A

Shine light in pupil, same pupil constricts.

Afferent: CN II
Efferent: CN III (sphincter pupillae) - parasympathetic

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25
Q

Consensual light reflex:

A

Shine light in pupil, other pupil constricts (in addition to the ipsilateral pupil).

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26
Q

Describe the pathway of the pupillary light reflex.

A

Retina, optic n., optic chiasm, optic tract, brachium of superior colliculus, pretectal midbrain, bilaterally to Edinger-Westphal, ciliary ganglion, short ciliary n., sphincter pupillae

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27
Q

Accommodation reflex circuit:

A

Afferent: Retina, optic n., chiasm, tract, LGN, visual cortex, visual association cortex, supraocular motor nuclei

Efferent: (bilaterally) Edinger-Westphal, oculomotor n., ciliary ganglion, short ciliary n., etc.

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28
Q

What is myopia?

A

Loss of distant acuity, due to genetic factors or overworked at short distances. OR the anteroposterior diameter of the eye is too long (parallel rays focus on vitreous humor (need concave lens)

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29
Q

What is hyperopia?

A

Loss of near acuity. Anteroposterior diameter of eye is too short. Parallel rays focus behind retina (need convex lens).

30
Q

What is astigmatism?

A

Curvature of corneal surface lead to un-uniform light passing through greater curvature (need cylindrical lens to equalize refraction)

31
Q

What is glaucoma?

A

Buildup of fluid within anterior chamber as result of block of canal of Schlemm (often) –> high pressure on eyeball –> damage to retina/optic nerve –> blindness, starting as a blur from the periphery (P > 20 mmHg is a danger)

32
Q

What is open-angle glaucoma?

A

Iris and corneal angle normal (cause unknown)

33
Q

What is closed-angle glaucoma?

A

Angle between cornea and iris is abnormally acute

34
Q

What is color confusion/blindness?

A

Lack of a certain cone type (commonly unequal recombination event - genetic). R/G hybrid gene leads to confusion of certain colors. Color perceived but not differentiated.

35
Q

L-cone:
M-cone:
S-cone:

A

red, green, blue

Red/green on X-chromosome, so more common in men. Blue is on autosome, so very uncommon.

36
Q

Protanopia:

A

Inability to detect pure red

37
Q

Deuteranopia:

A

Inability to detect pure green

38
Q

Tritanopia:

A

Inability to detect pure blue

39
Q

Retinitis pigmentosa:

A

Damaged retinal layer of rods and cones –> lack of light recognition in that eye (pupillary reflex, slower, and circadian rhythm ought to still work)

40
Q

Most common cause of blindness:

A

Retinitis pigmentosa, (rhodopsin gene), accumulation of opsin –> degeneration

Other cause is defect in arrestin binding rhodopsin to stop excitation (1st sign is night blindness, then tunnel vision)

41
Q

What is scotoma?

A

Symmetic or asymmetric, unilateral/bilateral shaped region(s) where vision is lost/reduced. Causes: toxins, retinal hemorrhage, trauma, tumor

42
Q

What is a monocular zone?

A

Temporal field seen only in corresponding eye

43
Q

What is a binocular zone?

A

Broad central region seen in both eyes

44
Q

Lesion of optic chiasm (pituitary tumor) leads to…

A

Bitemporal hemianopsia

45
Q

Impingement on lateral chiasm leads to…

A

Ipsilateral nasal hemianopsia (rare)

46
Q

Lesion of upper optic radiation:

A

loss of vision in contralateral INFERIOR visual field (contralateral inferior quadrantanopia)

47
Q

Lesion of lower optic radiation (Meyer’s Loop):

A

loss of vision in contralateral SUPERIOR visual field (contralateral superior quadrantanopia). Temporal lobe or fibers to calcarine sulcus.

48
Q

What is a congruous lesion?

A

Visual field loss of one eye can be superimposed on the other (lesion is closer to V1 - posterior)

49
Q

What is an incongruous lesion?

A

Visual field loss of one eye CANNOT be superimposed on the other. Lesion is more anterior in optic tract or radiations.

50
Q

Lesion of the visual cortex can result from ______ and lead to _____

A

Occlusion of calcarine artery/tumor; contralateral hemianopsia

51
Q

What is apperceptive agnosia?

A

Patient cannot identify objects due to perceptual deficit

52
Q

What is associative agnosia?

A

Patient can perceive object, face, or photograph but cannot attach meaning

53
Q

Perception lies in a different pathway than the processing of meaning.

A

It’s true!

54
Q

Right hemispheric lesions to inferotemporal region (18, 20, 21) (nondominant):

A

agnosia of drawing objects

55
Q

Left hemispheric lesions to inferotemporal region (dominant):

A

object agnosia - patient can’t recognize objects, but they are perceived

56
Q

Prosopagnosia often from bilateral lesion of _____

A

Fusiform gyrus

57
Q

What is stereopsis?

A

3-D and depth perception

58
Q

Congenital cataracts, strabismus, amblyopia can disrupt synapse formation in layer II bilaterally in critical period, leading to _____

A

permanent visual deficits (failure to orient eye)

59
Q

What is Balint Syndrome?

A
  • Optic apraxia: impairment of voluntary eye movement (esp. saccades; reflex preserved)
  • Simultagnosia: difficulty recognizing whole scene instead of just one object
  • Optic ataxia: inaccurate vision guided movement
60
Q

What causes Balint Syndrome?

A

Bilateral lesion to parietoocciptial junction region (medial superior temporal area - dorsal stream)

61
Q

What is alexia without agraphia?

A

Affected person can write but not read what they or anyone else wrote (usually along with homonymous hemianopsia)

62
Q

What causes alexia without agraphia?

A

Lesion in splenium of corpus callosum (visual info from one V1 to the other) WITH lesion to adjacent occipital region

63
Q

What is the accommodation-convergence (triple) reaction?

A

Focuses attention on a near object (involves ocular convergence, pupillary constriction, thickening of lens)

  • Medial rectus contract (converge eyes)
  • Contract ciliary m. (lens thickens)
  • Pupillary constriction (sharpen image on retina)

Visual association cortex –> superior branchium –> superior colliculus

64
Q

Summarize briefly the pathway of dilation:

A
  • Begins with amygdala/hypothalamus
  • IML cell column
  • Superior cervical ganglion
  • Postganglionic fibers in carotid plexus to dilator pupillae
  • Psym inhibited
65
Q

What is emmetropia?

A

State of vision where object at infinity is in sharp focus with lens in relaxed state

66
Q

What is optic neuritis?

A

Inflammation of optic nerve which can result in complete and partial loss of fiber input or blurring of vision

Common in MS.

67
Q

What is hemineglect?

A

Lesion in parietal cortex causing neglect of one whole visual field. Difficulty tying shoes and buttoning buttons.

68
Q

What is synesthesia?

A

Stimulation of one sensory/cognitive pathway causes an automatic experience of a second pathway
- Number-color: numbers are always the same color; abnormality in fusiform area as result of overgrowth of one cortical input (number area into color area)

69
Q

What is age-related macular degeneration (AMD)?

A

Loss of vision in center of visual field due to damage to the retina. Sign is yellow deposits (Drusen) in macula between retinal pigment epithelium and choroid

70
Q

Dry AMD:

A

Atrophy of retinal pigment epithelial layer below retina –> death of photoreceptors (90%). Better prognosis, not much treatment.

71
Q

Wet AMD:

A

Vision loss from abnormal blood vessel growth in choriocapillaries –> blood/protein in macula –> irreversible photoreceptor damage (10%). Worse prognosis, but treatment available:

  • Removal of blood before scar forms
  • Anti-VEGF

Neuroscience BB Exam 2 (7 decks)

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