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P seg Lab > VF > Flashcards

VF Flashcards

1
Q

relative unit of sensitivity in perimetry

A

Db

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2
Q

Unit of luminance/light density

A

Apostilb

*max luminance varies with VF

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3
Q

Hill of vision

  • What is it
  • Varies with what
  • Max sensitivity at
A

3D profile of pt’s retinal sensitivity

  • Varies with age, response of patient and light adaptation.
  • Fovea
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4
Q

Isopter

A

Line of equal retinal sensitivity plotted on a VF

Horizontal slice of HOV

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5
Q

Two types of scotoma

A

Absolute or relative

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6
Q

Two types of depression

A

Localized or general (real or artifact)

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7
Q

Causes of general depression

A

Could be due to media opacities, refractive error, ON disease, small pupil, poor pt attention, age

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8
Q

Contraction/constriction

A

Peripheral boundaries are moved inward

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9
Q

5 types of test paradigms

A
  1. Kinetic field. Goldman and tangent screen.
  2. Static field.
  3. Threshold. Stimulus that has 50% probability of being detected.
  4. Superthreshold. Screening. Presenting stimuli above expected threshold. Points noted as seen or not seen.
  5. Threshold related. 4 threshold test points. Remaining points tested at 6dB above threshold. More sensitive than 4
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10
Q

Visual field projection

A

VF on paper represents field as seen by the patient

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11
Q

Increasing or decreasing test distance.

What stays the same, what changes

A

Angular dimension does not change.
Lateral dimension will change proportionally with distance. Tangent screen utilizes this to check for hysterical amblyopia/tubular fields.

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12
Q

Damage to papillomacular fibers

A

Enter ON on the temporal side. Centrocecal defect.

Involves macula and blind spot.

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13
Q

Damage to temporal fibers

A

Arcuate defect

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14
Q

Damage to nasal fibers

A

Wedge defect

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15
Q

Superior and inferior fiber defects

A

Defects do not cross midline

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16
Q

Macular fibers initially run along which portion of ON

A

Outer

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17
Q

Altitudinal defect

A

Anterior ON damage close to retina

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18
Q

ON tract. The more posterior the damage

A

More likely it is to be congruous

19
Q

Optic radiation is located after the

A

LGN

20
Q

Pie in the sky defect

A

Damage to temporal/inferior/myers loop in optic radiation

21
Q

Pie on the floor defect

A

Damage to the parietal/superior loop in optic radiation

22
Q

Occipital cortex damage

A

Lesions here are highly congruous

Could exhibit macular sparring

23
Q

Frequency of seeing curve

A

Plots the percentage of time a stimulus is seen at a given intensity.
The gradient of the curve is a measure of the patient reliability. Steep is better.
Reliability increases with patient attention, previous test experience, additional auditory cues, multiple stimulus presentations.

24
Q

Sensitivity profile

A

Plots the change in retinal sensitivity with eccentricity. Varies with dark/light adaptation.

Photopic- steep
Mesoptic- flat
Scotopic- central depression

Affected by level of background illumination.
Pre adapted state of patient
Stimulus size

25
Q

Background illumination

A

Controls sensitivity profile and length of adaption of the patient.

26
Q

Adaptation time depends on

A

Background illumination
Prior state of adaption
Length of pre adaption period
Retinal eccentricity (greater sensitivity potential take longer)
-Local effect (ex bright fixation light will result in local area of reduction)

27
Q

Stimulus size

  • Due to ____ summation
  • Inverse relationship between size and ___
  • Based on what law
  • Spatial summation increases with
A
  • Spatial summation.
  • Between size and threshold. Small stimulus, complete inverse relationship. (Riccos law) with large stimuli, partial.
  • Riccos is luminance x area = constant
  • Spatial summation increases with eccentricity and dark adaption. (bigger fields in periphery)
28
Q

Blur can affect sensitivity due to increased spatial summation

A

True

29
Q

Goldman stimulus size ___ is normally used

A

III

30
Q

Stimulus duration

  • Due to ___ summation
  • Inverse relationship between duration and
  • Critical duration varies with
  • Saccadic reaction time
A
  • Temporal.
  • Threshold up to critical duration according to Bloch.
  • Bloch: luminance x duration = constant
  • Size, background illumination and retinal eccentricity.
  • Saccadic reaction time is 250 ms
31
Q

Keep stimulus duration between __ and __ msec

A

100 and 250

32
Q

5 types of perimetry

A

Confrontation - Static or kinetic
Ampler
Tangent - Kinetic or static. Tubular field.
Goldman- gold standard. Manual. Kinetic and static. Longer in duration than other forms.
automated

33
Q

4 types of automated perimetry

A

Humphrey - projects stimuli in bowl. Must correct for test distance for presbyopes. Static.

Octopus- Projects stimuli onto retina. Tests 30 degrees only. Only correct distance Rx. Static.

Dicon- Kinetic/dynamic only. Has sounds.

Frequency doubling tech (FDT)- Static.

34
Q

3 components of automated perimetry

A
  1. LED vs projection stimuli.
    - LED cannot alter size or color. Silent.
    - Projection can alter size and color. Makes noise.
  2. Fixation target
    - Humphrey, octopus and FDT all use static.
    - Dicon uses dynamic/kinetic
  3. Fixation monitor using Heijl Krakau method.
    - K purkinje image alignment used for humphrey gaze tracking.
35
Q

Quantify defects test strategy

A

Missed points are ran at threshold level. All others are super

36
Q

Humphrey analyzer algorithms

A
  1. Fast Pac. 40% less time than full threshold.
  2. SITA standard. 50% less than full threshold.
  3. SITA Fast. 50% faster than Fast pac
  4. SWAP. Blue stimulus on yellow background. Early detection of glaucoma since glaucoma damages short wavelength fibers first.
37
Q

SWAP test

  • What is it for
  • Significant dB values
  • Requires what type of patient
A

Blue stimulus on yellow background. Early detection of glaucoma since glaucoma damages short wavelength fibers first.

HOV drops more rapidly. 9db Centrally or greater than 9Db peripherally is significant.

Requires young attentive patient with no lens opacities.

38
Q

Greater than what percentage indicates low patient reliability for

Fixation loss
False Positive
False negative

A

more than 20
more than 33
more than 33

39
Q

High FN rate could indicate

A

Disease

40
Q

Short term fluctuation (SF)

  • Greater than what is considered high
  • What does it indicate if high
  • Could be early detection of
A
  • Greater than 0.3 is high
  • Indicates variability of patient response.
  • Could be early indication of pathology
41
Q

4 types of reliability indicies

A

Fixation loss
False Positive
False negative
Short term fluctuation (SF)

42
Q

Types of statistical analysis

A

Raw data
Grey scale
Probability plots
Central reference level
Defect depth plot
Total deviation plot - Shows local and overall defects
Pattern deviation plot- only shows local defects

43
Q

Types of global indicies

A

Mean deviation - elevation of depression of overall sensitivity. Normal is +/- 2

Pattern standard deviation: 0 to 2. High value indicates patient variability in responses.

Short term fluctuation- Normal is less than 3. Response consistency.

Corrected pattern standard deviation- Corrects for SF. Abnormal is p < 5%. Indicates field abnormalities. Can be fooled by advanced glaucoma !

P seg Lab (8 decks)

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