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U5 Neuroscience > Visual Field Defects > Flashcards

Visual Field Defects Flashcards

1
Q

What is the definition of a visual field?

A

The area of space that a eye can perceive

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2
Q

What is the name of the process used to assess the visual field?

A

Perimetry

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3
Q

What is the normal temporal angle for a visual field? What is the normal nasal angle for the visual field? What are the angles to which we can see superiorly and inferiorly?

A

Temporal angle: 100 degrees
Nasal angle: 60 degrees
Superior/Inferior angles: 60 degrees

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4
Q

What is the blind spot in the eye due to? Why don’t we notice it?

A

Optic nerve; the brain fills in this blind spot

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5
Q

When you look at a fixation point in the center, what are you using to perceive this image?

A

Fovea- within the macula

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6
Q

What part of the visual field does the nasal retina perceive? What part of the visual field does the temporal retina perceive?

A

Nasal retina perceives the temporal visual field while the temporal retina perceives the nasal visual field

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7
Q

What anatomical feature divides the nasal and temporal retina?

A

Fovea

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8
Q

The area from 60 to 100 degrees that can only be perceived by one eye at a time is known as what?

A

The temporal monocular crescent

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9
Q

What area represents the binocular visual field? The nasal visual fields of both eyes, the temporal visual fields of both eyes, the nasal retina, or the temporal retina

A

The nasal visual field of both eyes, which would be perceived by the temporal retina of both eyes- this represents the overlapping visual field of both the right and left eye

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10
Q

In a diagram of Tranquir’s Island of vision, that represents a visual field with an x, y, and z axis, what does the z axis represent?

A

Sensitivity of the visual field

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11
Q

In a diagram of Tranquir’s Island of Vision, where can one find the best acuity of 20:20 vision?

A

The tip of the island

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12
Q

What is the most important factor that affects visual sensitivity (or the shape of Tranquir’s island of vision)?

A

Character of the stimulus- the size, intensity, shape, color, duration, and movement of the stimulus

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13
Q

When will you first see a bright, larger object moving in from the periphery- when it first hits your island of vision or close to the tip of the island? What about a dim, smaller object?

A

Bright, large object: see as soon as it hits the island

Dim, small object: won’t be seen until it hits the tip of the island, or is right in front of your fovea

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14
Q

Moving in object from the periphery into the center and noting when the patient can see it is known as what form of perimetry?

A

Kinetic perimetry

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15
Q

Using a stationary object and then making it brighter until the patient can see it is known as what form of perimetry?

A

Static perimetry

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16
Q

What are the advantages and disadvantages of using confrontation visual fields to assess a patient’s visual field?

A

Advantages: inexpensive, fast, practical
Disadvantages: dependent on both the examiner and the examinee

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17
Q

When performing a confrontation visual field what should the examiner do?

A

Have the patient cover one eye with their palm, with the examiner covering the contralateral eye, then ask if the patient sees the examiners face, followed by finger counting (ask how many fingers in each quadrant), then finger waving from periphery, and then bring in a red object which has requires a higher sensitivity

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18
Q

What is a hemianopia?

A

A nasal or temporal defect where you can only see one or the other- can only see the nasal visual field or the temporal visual field

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19
Q

How do you use an Amsler grid to test visual field defects?

A

Place the small grid at 33cm and ask if patient has an missing, blurred, or distorted lines on the grid

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20
Q

How do you use a Tangent screen to assess visual field?

A

Examiner stands 1m away from the examinee, facing them, and brings an image in from each side

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21
Q

Amsler grid testing and tangent screen testing use: static perimetry or kinetic perimetry?

A

Kinetic perimetry

22
Q

What is the definition of scotoma?

A

A chunk of the visual field is missing

23
Q

The mean deviation provided by the Humphrey visual field test, gives you what information?

A

The weighted average of all visual defects in one eye

24
Q

What causes an arcuate visual field defect?

A

Arc like shaped defect caused by retinal nerve fiber damage

25
Q

What is a altitudinal visual field defect?

A

Either a superior or inferior visual field defect- split at the horizontal

26
Q

What is a quadranopia?

A

Visual field defect in one quadrant

27
Q

Relative versus absolute visual field defects differ in what aspect?

A

Relative visual field defects are only abnormal for certain stimuli while absolute are abnormal regardless of which type of stimulus is used

28
Q

A defect in the temporal field of the right eye and the nasal field of the left eye is considered to by homonymous or heteronymous?

A

Homonymous- both affect the same side of the eye

29
Q

A defect in the temporal field of the right eye and the temporal field of the left eye is considered to be homonymous or heteronymous?

A

Heteronymous- affecting different sides of the eyes

30
Q

What does congruous mean?

A

The visual defect is similar in both the right and left eye

31
Q

What is the anatomical pathway from the retina to the occipital lobe?

A

Retina, optic nerve, optic chiasm, optic tract, LGN, optic radiations, calcarine fissure

32
Q

What divides the retina into the superior and inferior aspects?

A

Horizontal raphe

33
Q

What two visual field defects would you expect with a retinal defect?

A

Central scotoma from a foveal lesion or arcuate defect from glaucoma

34
Q

What are three visual field defects that can be seen when there’s a defect in the optic nerve?

A

Altitudinal field defect, central depression, or central scotoma

35
Q

What usually causes an altitudinal field defect?

A

Anterior ischemic optic neuropathy- (NAION)

36
Q

What fibers cross in the bottom of the optic chiasm? What part of the visual field do these fibers contain?

A

Fibers from the inferior nasal retina

Carry the superior temporal visual field

37
Q

What fibers cross at the top of the optic chiasm? What part of the visual field do these fibers contain?

A

Fibers from the superior nasal retina

Carry the inferior temporal visual field

38
Q

A pituitary tumor is most like to push against the lower portion of the optic chiasm, producing what kind of visual field defect?

A

Bitemporal supratemporal field defect

39
Q

The fibers from the inferior nasal retina do something different immediately after reaching the optic chiasm, what is this?

A

Loop around the opposite optic nerve forming Wilibrands knee and then return to the optic chiasm

40
Q

What is significant about Wilibrands knee if the optic nerve is cut?

A

Lose the complete vision in one eye, but also part of the visual field in the opposite eye- pie in the sky

41
Q

What happens to the axons from the fovea after they leave the retina?

A

Cross in the center of the optic chiasm; very hard to damage from physical force because so deep

42
Q

What is the hallmark visual field defect when the lesion affects the body of the chiasm?

A

bitemporal visual field defects

43
Q

A lesion beyond the optic chiasm produces what type of visual field defects?

A

Homonymous

44
Q

The more posterior the lesion is, with regard to the retinochiasmal pathway, the visual field defect is said to be more congruous or incongruous

A

Congruous

45
Q

What visual field defect is seen with a lesion at the optic tract? What other symptoms are seen?

A 
Incongruous homonymous field defect
Contralateral RAPD (pupillary reflex)
Contralateral paresis from the proximity to posterior limb of internal capsule
46
Q

Lesion in the LGN of thalamus causes what kind of visual field?

A

Homonymous sectoranopia

47
Q

After synapsing in the LGN, axons then travel to via the parietal and temporal radiations to the calcarine sulcus. What visual field is contained in the parietal and temporal radiations?

A

Parietal radiation: carries the inferior field

Temporal radiation: carries the superior field

48
Q

Which optic radiation goes directly to the calcarine sulcus? Where does the other radiation go before going to the calcarine sulcus?

A

Parietal goes directly to the calcarine sulcus

Temporal loops around forming Meyer’s loop in the rostral part of the temporal lobe before going to the calcarine sulcus

49
Q

The cuneate receives which optic radiations; the lingual gyrus receives which optic radiations?

A

Cuneate receives parrietal optic radiations

Lingual receives temporal optic radiations

50
Q

With which type of lesion do you see macular sparing?

A

Occipital lobe lesion

51
Q

Where do the monocular temporal crescent axons go in the occipital lobe?

A

The most anterior part of the calcarine fissure

U5 Neuroscience (35 decks)

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