Strabismus (M2) Flashcards by Tyler Dowdall

When testing a patient with strabismus that has a reduced VA, what needs to be done?

test with pinhole
rule out pathology
evaluate for eccentric fixation

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What needs to be noted and looked for when assessing ductions and versions?

restrictions, underactions, or overactions

2. associated lid movements (narrowing of palpebral fissure on adduction)

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What is the position of gaze where a muscle is the primary mover of the eye called?

field of action

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What is the control assessment protocol for a strabismic?

do prior to any dissociation
30sec observe as patient accom at dist
30sec observe as patient accom at near
if no tropia at dist, determine time to recover fusion after 10sec dissociation (worst of 3 trials)
if no tropia at near, determine time to recover fusion after 10sec dissociation (worst of 3 trials)

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What is the description of a grade 5 on the IXT control scale? 1. Grade 4? 2. Grade 3? 3. Grade 2? 4. Grade 1? 5. Grade 0? 6

constant exotropia
XT more than 50% before dissociation
XT less than 50% before dissociation
XT only with dissociation, recovers in longer than 5sec
XT only with dissociation, recovers in 1 to 5sec
XT only with dissociation, recovers in less than 1sec

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How should the objective angle or angle of deviation be measured for a strabismic patient?

at distance and near in the 9 cardinal positions of gaze with accommodative target

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What needs to be noted about a cover test for a strabismic patient?

laterality
frequency
direction

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When performing the simultaneous prism cover test, which eye do you put the prism in front of?

deviating eye

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If there is an acute onset strabismus or suspected palsy, what is done differently about the cover test?

perform cover testing with each eye as the fixing eye

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How far is the penlight held from the patient in Angle Kappa?

40cm

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What does a difference between angle kappa between the two eyes and reduced acuity in one suggest?

eccentric fixation

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Which eye is the prism placed in front of during Krimsky testing? 1. What must the patient have for this to work? 2

fixing eye

2. range of fusion around objective angle to align reflexes

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What distance is the light held at during Bruckner testing? 1. How do you interpret the results? 2

2. brighter reflex is deviating eye

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When is the true deviation different from the deviation you measure?

eccentric fixation
stacked prisms in same direction
deviation over 30pd and pt has 5D or more refractive correction

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How does the measured deviation compare to the true deviation for a esotrope with nasal eccentric fixation?

measured less than true

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How does the measured deviation compare to the true deviation for a exotrope with nasal eccentric fixation?

measured greater than true

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How does the measured deviation compare to the true deviation for a esotrope with temporal eccentric fixation?

measured greater than true

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How does the measured deviation compare to the true deviation for a exotrope with temporal eccentric fixation?

measured less than true

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What is the equation to determine the effect of eccentric fixation on the true deviation?

D(true) = D(msr’d) + EF
+ for eso and nasal EF
- for exo and temporal EF

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If two prisms are stacked in the same direction, is the resulting prism greater or less than the sum of the two prisms?

greater than

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Do plus lenses increase or decrease the measured deviation?

decrease

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Do minus lenses increase or decrease the measured deviation?

increase

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What are the subjective tests for the evaluation of comitancy?

red lens test

2. Hess Lancaster screen

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What are the objective tests for the evaluation of comitancy?

cover test in 9 positions of gaze

2. three step test

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When performing the red lens test, which eye should you place the red lens in front of first?

non paretic eye

When performing the red lens test, if the patient has an exo deviation is the diplopia crossed or uncrossed?

crossed

When performing the red lens test, if the patient has an eso deviation is the diplopia crossed or uncrossed?

uncrossed

When performing the Hess Lancaster screen, if the patient has an exo deviation is the diplopia crossed or uncrossed?

uncrossed

When performing the Hess Lancaster screen, if the patient has an eso deviation is the diplopia crossed or uncrossed?

crossed

When performing the red lens test, which eye sees the leading image?

eye with paretic muscle

When performing the Hess Lancaster screen, which eye sees the leading image?

eye with normal muscle (paretic lags)

When performing the Hess Lancaster screen, does the fixating eye view the examiners or the patients target?

examiners

If there is a greater hyper deviation with a head tilt to the same side as the original deviation, what type of muscle is involved?

oblique

If there is a greater hyper deviation with a head tilt to the opposite side as the original deviation, what type of muscle is involved?

rectus

What degree of fusion is being measured with the superimposition of dissimilar targets?

first degree

What degree of fusion is being measured with the fusion of common borders?

second degree

What degree of fusion is being measured with stereopsis?

third degree

What can be used to determine the level of fusion? 1. What is the unit of measurement for this? 2

1. troposcope | 2. prism diopters

What is it called when superimposition and 2deg fusion is not possible and the target gets closer, disappears, and then reappears on the opposite side of the target?

horror fusionalis or horror fusionis

What is it called when you are measuring the level of fusion and the targets are on top of each other but not superimposed?

central fusion disruption

What is the theory of etiology of eccentric fixation where EF = anomalous correspondence?

Cuppers

What is the theory of etiology of eccentric fixation that there is suppression of the fovea to eliminate diplopia?

Worth

What is the theory of etiology of eccentric fixation that eccentric fixation is artifact of motor output based on registration of eye movements?

Schor

What are the things we need to determine and record about eccentric fixation?

1. amount 2. direction 3. steadiness

What are the conditions that visuoscopy should be done?

1. red free 2. dec illumination 3. dilation

For the Haidinger Brush (MITT box), if the brush is seen 3cm tot he left of the fixation dot with the right eye at 0.5m away, what is the fixation disparity?

6pd nasal eccentric fixation

What test for eccentric fixation can only be done if the patient has normal correspondence?

after image transfer

During the after image transfer, if a patient views the AI 1cm to the left f the fixation dot while testing at 50cm in the right eye, what is the deviation?

2pd nasal eccentric fixation

What is the equation to calculate the expected visual acuity based on an eccentric fixation value?

EF + 1 = MAR = x/20

What is suppression attributed to?

cortical inhibition

What is the size of foveal suppression? 1. Central suppression? 2. Peripheral? 3

1. less than or equal to 1deg (2pd) 2. btw 1 and 5deg (2 to 10pd) 3. greater than 5deg (greater than 10pd)

What are the tools that can be used to diagnose suppression?

1. orthoscope 2. Worth dot 3. polarized 4 dot 4. troposcope 5. 4 BO test 6. synoptophore

What is the problem with the Worth 4 dot for diagnosis of suppression?

patients can change status based on laterality of filters

What are the eye movements expected to be seen in a normal patient during the 4BO test?

1. version movement by both eyes | 2. eye without prism in front converge to fuse target

What are the eye movements expected to be seen in a central suppression patient during the 4BO test in front of the fixing eye?

1. version movement by both eyes | 2. no fusion vergence movement

What are the eye movements expected to be seen in a central suppression patient during the 4BO test in front of the suppressing eye?

1. no movement of either eye

What devices can be used to measure the depth of suppression?

1. Bagolini bar filter 2. Worth dot or polarized 4 dot in light vs dark 3. troposcope

What is a neural adaptation to eye misalignment in which noncorresponding retinal points are linked in the visual cortex to provide binocular fusion?

anomalous correspondence

What is the idea the H and A change in concert while S = 0?

covariation of angle of anomaly in anomalous correspondence

What is the innate theory of etiology of anomalous correspondence?

born with it to prevent diplopia

What is the sensory adaptation theory of etiology of anomalous correspondence?

adaptation to sensory problems of strabismus that evolves from NC

What is the motor adaptation theory of etiology of anomalous correspondence?

always present in strab due to version anomaly. Changes in correspondence

What is the letter that denotes the angle of deviation or the objective angle? 1. What is the sign of eso? 2

1. H, D, or O | 2. +

What is the angle where the patient perceives fusion? 1. What is the sign of eso? 2

1. subjective angle (S) | 2. +

What is the difference between the subjective and objective angles called? 1. What does it mean if it is positive? 2. Negative? 3

1. angle of anomaly (A) 2. crossed separation of foveal tags 3. uncrossed separation

What is the type of correspondence where the subjective and objective angles are equal with an angle of anomaly of zero?

normal correspondence

What is the type of correspondence where the subjective and objective angles are equal and there is a difference between the two?

anomalous correspondence

What is the type of correspondence where the subjective angle is zero despite there being a strabismus (H=A)?

harmonious anomalous correspondence (HAC)

What is the type of correspondence where the subjective angle greater than 0, H is greater than S and A?

unharmonious anomalous correspondence (UHAC)

What is the type of correspondence where the angle of anomaly is greater than the objective angle (S is in the opposite direction to H)? 1. What is this due to? 2

1. paradoxical anomalous correspondence (PAC I) | 2. EOM surgery

What is the type of correspondence where the subjective angle is greater than the objective angle (A in opposite direction to H)? 1. What is this due to? 2

1. paradoxical anomalous correspondence (PAC II) | 2. EOM surgery

What are the methods of measuring correspondence that compares subjective and objective angles?

1. Bagolini Lens test 2. troposcope 3. red lens with vertical prism

What are the methods of measuring correspondence that directly measure the angle of anomaly?

1. HBAIT 2. Haidinger Brush AI test 3. bifoveal test of Cuppers

How should the notches be oriented from a doctors point of view during Bagolini testing?

135deg OD, 45deg OS

What is done to assess the objective angle during the Bagolini testing?

perform unilateral cover test over any prism used to neutralize subjective angle

If a tropia is noted on UCT when doing Bagolini lenses with a S=0, what is the correspondence? 1. Not seen? 2

1. HAC | 2. NC

If a esotropia is noted on UCT when doing Bagolini lenses with a S being +, what is the correspondence? 1. Not seen? 2. Is the diplopia crossed or uncrossed? 3

1. UAC 2. NC 3. uncrossed

If a exotropia is noted on UCT when doing Bagolini lenses with a S being -, what is the correspondence? 1. Not seen? 2. Is the diplopia crossed or uncrossed? 3

1. UAC 2. NC 3. crossed

What is the problem with the major amblyoscope (troposcope)?

AC less likely to be found since it is less natural

How is the objective angle found in a troposcope? 1. Subjective angle? 2

1. alternate flash and move arms to neutralize | 2. illuminate both tubes to match images to align

If there is no movement on the douse test (performed with subjective) for the troposcope, what is the type of correspondence?

How can the Worth 4 dot be used to test correspondence?

add horizontal prism until patient sees all four dots. Then do objective on top of that

Is the Hering Bielschowsky AI test affected by eccentric fixation?

yes

What is the procedure for the Hering Bielschowsky AI test?

1. occlude deviating eye and flash horizontal 2. occlude better eye and flash vertical 3. ask where after images are in relation to each other

What is it called when the after image is not lined up at first but then lines up after a few seconds?

covariation

What should be done to rule out pathology in all strabismic patients?

1. pupils 2. DFE 3. visual field

What are the general etiologies of strabismis?

1. refractive 2. organic and sensory 3. anatomic and motor (abnormal location of pulleys) 4. innervational 5. 50% unknown

What are the traits that are found in innervational strabismis?

1. abnormal AC/A 2. weak fusion ability 3. abnormal tonic innervation to EOMs 4. abnormal central coordination

What is a change in fixation at the midline of each eye called?

cross fixation

What is the area of hyperopia that is in controversy for prescribing?

+3.00 to +5.00

Is HBAIT or Bagolini better at detecting covariation anomalous correspondence?

HBAIT

When is microtropia suspected?

1. unilateral dec in VA with no RE, organic cause, or strabismus 2. small fixation movement on UCT

Strabismus (M2) Flashcards

(92 cards)