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BV Flashcards

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1
Q

Tests that measure the direction and magnitude of the ocular deviation

A

CT
VG phoria (cannot differentiate phoria from tropia)
Maddox rod (cannot differentiate phoria from tropia)
Modified thorington (cannot differentiate phoria from tropia)
FD (only one measured under associated conditions)

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2
Q

Direct and indirect tests that measure vergence

A

Direct: Smooth vergence, step vergence, vergence facility

Indirect: NRA/PRA, FCC, bino accommodative facility, MEM ret.

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3
Q

2 tests that measure sensory status- suppression and stereo

A

Ran dot and Worth 4 dot

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4
Q

Phi phenom during CT

A

Exo sees image move with paddle

Eso sees image move opposite of paddle

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5
Q

Crossed, uncrossed, homo, hetero

A

Eso: Uncrossed, homo
Exo: Crossed, hetero

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6
Q

Modified Thorington

A

Purpose: Subjective, dissociated test that measures mag and direction of deviation. (cannot differentiate phoria from tropia)

Card held at 40cm
Pt holds maddox rod over rt eye, dr shines light through the center of the card

Similar to maddox rod but has numbers on the graph

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7
Q

Fixation Disparity

  • What is it
  • Examples of tests that measure FD
A

Very small misalignment of the visual axes (measured in minutes of arc)
NOT observed with standard tests for ocular alignment. The object falls within Panums fusional area for the corresponding retinal points in each eye, therefore, it is seen as single.

Always measured under associated conditions

Wesson and Sheedy tests measure FD.

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8
Q

How to use the Wesson card to measure FD

A

Associated conditions
Pt holds Wesson card at 40cm while wearing polarized glasses.
It has a black arrow pointing up to colored lines. The pt tells you which color the arrow is pointing to. Technically, it’s always pointing to the center red line but it will appear to be displaced for a patient with FD.

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9
Q

4 types of FD curves and what are the X and Y axes

A

X: Associated phoria (the amount of prism required to neutralize the FD)
Y: FD

1- Most common, prob asymptomatic
2- Eso
3- Exo
4- Unstable.

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10
Q

How to calculate ACA ratio

A

Multiply the accommodative stimulus amount x distance pd in cm. This is the stimulus to converge.

Map out their tonic and near phoria.
Figure out the change in convergence based on the stimulus to converge number / change in accommodation.

Change in convergence/ change in accommodation

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11
Q

2 types of ACA

A

Cacluated/Frys ACA- measured at 2 distances. Proximal convergence may cause a larger ACA.

Gradient ACA- Measured at the same distance with 2 different lenses.

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12
Q

How to treat patients with low or high ACA

A

High ACA patients will respond well to sphere lenses. An eso pt with high ACA ratio will significantly relax their accommodative convergence with addition of small plus.

Low ACA patients respond better to prism or VT

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13
Q

Smooth vergences

What does the blur break and recovery mean

A

Blur- ran out of fusional vergence (PFV and NFV)
Break- ran out of fusional AND accommodative vergence

Recovery should be at least 1/2 the break. Assess the flexibility of the bino system to regain fusion after diplopia occurs.

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14
Q

Sheard and percivals is better for estimating prism in esos or exos?

A

Sheard- exo

Percival- Eso

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15
Q

Sheard

A

Good at estimating prism for exo

Compensatory fusional vergence (blur) should be at least 2x the phoria.

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16
Q

Percival

A

Good at estimating prism for eso
Smaller fusional vergence reserve should be at least 1/2 the greater fusional vergence reserve. This places the demand within the middle 3rd of the zone of clear binocular vision.

Does NOT take into account the amt of phoria

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17
Q

Vergence facility testing

A

12 BO and 3 BI flippers.
Have pt view a near card.
Norm: 15 cpm (cycle= clear BO and BI)

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18
Q

NPC norms

A

5/7

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19
Q

Amp minimum, average, max

A

Min: 15-1/4 age
Avg: 18.5- 1/3 age
Max: 25 - 2/5 age

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20
Q

Minus lens test to measure accommodation

A

Subjective measurement of amp
Pt is behind horopter looking at 40cm target.
Add minus until completely blurred.

If you could add -2.00D then add that to the stimulus of -2.50 at 40cm. Add +0.50 back to account for minification.

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21
Q

accommodative facility testing

A

+2/-2 flippers

8cpm bino
11cpm mono

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22
Q

How to interpret accommodative facility results

  1. Inadequate clearing of plus and minus
  2. Inadequate clearing of plus under mono and bino
  3. Inadequate clearing of minus under mono and bino
  4. Inadequate clearing of plus/minus under bino, normal under mono
A
  1. Poor facility
  2. Over accommodation. can’t relax.
  3. Accommodative insufficient. Cant stimulate.
  4. vergence problem, normal accommodative system.
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23
Q

Main difference between MEM and FC

A

MEM OBJECTIVELY determines the accuracy of the accommodative response.

FCC SUBJECTIVELY determines the accuracy of the accommodative response.

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24
Q

NRA/PRA norms

A

+2.50/-2.50

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25
Most common non-accommodative binocular vision disorder
CI | Affects 3-5% of the population
26
Difference between CI and pseudo CI
Pseudo CI is an accommodative problem leading to decreased convergence. Unlike a normal CI, pseudo CI will have decreased Amp and respond well to plus. They will not like minus= low PRA.
27
CI is longstanding problem. What if the patient presents with sudden symptoms?
MS and MG (fatigue)
28
Least common non-strab bino vision disorder
DI
29
DI symptoms and signs
Least common BV disorder Intermittent diplopia at distance that is worse at the end of the day. Fatigue, blurry vision, difficulty focusing from far to near More eso at distance, low ACA, low PRA/NFV at distance. Differential: CN 6 palsy (non-comitant eso deviation)
30
Differential for DI
CN 6 palsy | If you do CT in different directions of gaze, you will see that the palsy has non comitant deviations.
31
CE must be differentiated from pathologic causes of accommodative/convergence spams such as
Inflammation: uveitis, scleritis CNS disease: Tertiary syphilis (accommodates well but no direct response) or Sympathetic paralysis (parasympathetic takes over) Pharm: Parasymp drugs
32
most common symptom of DE
Diplopia Most common symptoms are cosmetic because the eye turns out or the patient covers an eye in bright light May have V pattern
33
Vertical phoria signs
Head tilt, reduced PFV and NFV, reduced vergence facility with BO and BI. Vertical dysfunction may contribute to the development of horizontal BV disorders. Vertical ranges may be constricted if recent onset, or larger if longstanding.
34
Fusional vergence dysfunction
Tight fusional ranges under bino conditions. Normal accommodation mono.
35
signs of accommodative insufficiency
Reduced amp Don't like minus lenses- reduced PRA and NFV high Lag bc like plus Inability to clear minus lenses bino and mono. DDX: Pseudo CI
36
2 subsets of accommodative insufficiency
Ill sustained accommodation | Accommodative paralysis
37
Accom insuf Accom Excess Which one likes plus? Minus?
Insuf likes plus | Excess likes minus. Basically causing themselves to be pseudo myope.
38
Accommodative excess
Difficulty shifting focus from far to near Normal to high amp They like minus, hate plus. Will have reduced NRA/PFV, low lag, inability to clear plus bino and mono PSeudo myopia- cyclo them.
39
Main difference between accommodative excess and spasm
Excess- Patient over accommodates, inducing pseudo myopia. They like minus lenses. Plus lenses will NOT work. Spams- Result of fatigue due to over stimulation of the accommodation system. Plus lenses will reduce symptoms
40
Accommodative infacility
Difficulty cleaning plus and minus on binocular and mono facility testing. Reduced NRA and PRA overall because their accommodation system is not very robust/flexible.
41
3 mechanisms that the visual cortex uses to avoid poor sensory fusion (Retinal images appear significantly different, localized in different retinal areas. Images must be clear, same size and fall on corresponding retinal points for sensory fusion)
Suppression --> Amblyopia Eccentric Fixation ARC
42
Images must be _____ for sensory fusion to occur
clear, same size and fall on corresponding retinal points
43
Amblyopia definition
20/30 or worse in one eye or a difference of 2 or more lines of visual acuity between the two eyes that is not correctable with refraction and not explained by structural abnormalities.
44
Amblyopia occurs at the level of the
Visual cortex
45
When does amblyopia develop
Will only develop from dissimilar retinal images that occur during the critical period of development of the visual cortex. Birth to 7-9 years. The first 2-3 years are the MOST sensitive for development of the visual cortex.
46
What is the crowding phenomenon
Common in patients with amblyopia Difficulty distinguishing between letters or words that are close together. Do VA with one letter on the chart instead of a line.
47
3 main forms of amblyopia
Refractive Form deprivation (occlusion) Strabismic
48
Causes of form deprivation/occlusion amblyopia
congenital cataracts, ptosis, corneal opacities | Early dx during the sensitive period is critical
49
which is more likely to lead to amblyopia? Aniso hyperopia or myopia?
Aniso hyperopia Eyes will accommodate the smallest amount possible in order to obtain a clear image. Both eyes accommodate the same, leaving the more hyperopic eye with an always blurred image.
50
3 types of refractive amblyopia
Anisometropic- Difference in refractive error between the two eyes. Aniso hyperopia more at risk of developing amblyopia. Isometropic- Poor connections between each eye and the visual cortex. Meridional- Due to uncorrected astig during the sensitive period.
51
How to remember potential amblyogenic refractive errors
Mike is 38. He dated Hannah who is 15 His ass is going to jail for 15-25 years First number is aniso Second number is iso
52
Strabismic amblyopia
occurs when there is a binocular misalignment of the visual axes of the eyes that is larger than panums--> Diplopia and confusion --> suppression at the level of the visual cortex. Will only occur if its constant and unilateral.
53
Define diplopia and confusion
Diplopia: Object falls on non corresponding retinal points because the fovea in one eye is deviated. The object appears in 2 different visual directions. Suppression in the peripheral retina eliminates diplopia. Confusion: When each macula views a different object due to deviation. Dissimilar objects appear in the same visual direction. Suppression at the fovea eliminates confusion.
54
Eccentric fixation
Monocular. Occurs when a non-foveal point is used for fixation in the strab eye under monocular conditions. Can occlude the other eye and this eye will still turn. Esotropes develop nasal EF and exotropes develop temporal EF. Paradoxical EF is when these points are switched. Ex: Esotrope uses temporal EF pt. During CT, the objective measurement will appear less than it actually is because the patient will fixate with the eccentric point rather than going to the fovea for fixation.
55
What test is used to dx Eccentric Fixation
Haidinger's brush | If pt uses an EF point, they will see Haidinger's brush centered on a point other than the fixation target.
56
Main difference from EF and ARC
EF- monocular. Cover the other eye and this eye will stay turned to its spot. Non foveal point being used in strab eye- otherwise healthy. (Eccentric viewing is in unhealthy eye) ARC- binocular. Cover the other eye and this eye will straighten out. Under monocular conditions, the deviated eye will use the fovea to fixate the target. * in both, eso will use nasal pt, exo will use temporal pt.
57
When does ARC occur
Occurs if the foveal misalignment occurs before age 5 Visual cortex responds by this to eliminate confusion
58
Angle of anomaly is the difference between
Objective and subjective angle of deviation Think AOSA Angle of anomaly = objective - subjective
59
Harmonious ARC
When the angle of anomaly = objective angle of deviation The new fovea of the deviated eye corresponds with the fovea of the fellow eye so that the subjective angle of deviation is zero. The patient will not have symptoms of diplopia or confusion Angle of anomaly = O- S In this scenario, objective- zero = Anomaly Angle of anomaly = objective Most common type of ARC.
60
Unharmonious ARC
When the angle of anomaly is less than the objective
61
Hirschberg
Patient views a light at 50cm fro midline with both eyes open. Compare to angle lambda, which is 0.5mm nasal in each eye under monocular conditions. nasal displacement-exo (-) Temporal- eso (+) Upwards- Hypotropia Down- Hypertropia
62
Angle lambda
The angle between the pupillary axis and line of sight (through pupil to the fovea) Measured on monocular conditions 0.5mm nasal Only angle we can clinically measure
63
a 1mm shift in the corneal light reflex during hirschberg indicates
22 pd
64
Purpose of the bruckner test
Detect strab, aniso, and/or media opacities in infants
65
How to do the Bruckner test
Use DO 80-100cm away from the patient. Compare the red reflexes. The darker reflex = eye with media opacity or fixating eye Brighter reflex= eye with higher uncorrected refractive error or strab eye
66
Purpose of visuoscopy and how to interpret results
Detect eccentric fixation Grid is superior to FLR? Superior eccentric fixation Grid is temporal to FLR? Temporal eccentric fixation
67
Tests to determine eccentric fixation
Haidingers brush, maxwells spot, monocular hirschberg, visuoscopy
68
Tests for retinal correspondence
After image- tag each fovea. | Bagolini- most sensitive
69
How does the after image test determine ARC
Tag each FOVEA- horizontal line for non strab eye and vertical line for strab eye. If the fovea is nasal to the new fovea, the vertical line will be perceived as coming from temporal space. Vertical line will be displaced to the right. If the patient has NRC, they will see a perfect cross- even if there is ocular misalignment. Because both foveas are linked.
70
Bagolini lens purpose and how do they work
Most sensitive test for retinal correspondence, can also determine suppression. Have them put the glasses on and ask what they see. Do CT if their eyes aren't aligned
71
4 levels of sensory fusion
Zero: no fusion. Monocular or suppressing First: Bi-ocular. Superimposition targets. Patients will have diplopia. Second: Flat fusion. Pts do not have diplopia Third: Stereo. Requires motor and sensory fusion
72
worth 4 dot - Purpose - How To - Interpretation
Detects suppression and flat fusion. Do if stereo is below 40 seconds of arc. Pt wears red/green glasses with red over OD. OD sees red target, OS sees green target. 2 red dots- OS sup 3 green dots- OD sup 4 dots- flat fusion, no sup 5 dots seen- diplopia If the patient suppresses at near and in the dark, the patient has a large and deep suppression
73
2 types of targets used to assess stereo, both seen on Ran dot
``` Contour/local= wirt circles. Laterally displaced targets with monocular cues. Global/stereo= uses random dot targets with no monocular clues. ```
74
4 categories of estotropia
1. Infantile 2. Acquired 3. Secondary 4. Micro ET
75
4 categories of exo deviations
1. Infantile 2. Acquired 3. Secondary 4. Micro XT
76
2 main areas of visual perceptual processing tests
1. Visual spacial: Standing angles in the snow, piagets laterality test, Jordan left and right reversal test (directionality) 2. Visual perception: Visual discrimination, visual closure, form constancy, figure ground discrimination, visual spatial relations and visual memory. TVPS, MFVP, DTVP

KMK Ocular Motility (2 decks)

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