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X. Strabismus > Exotropia — COMPLETE > Flashcards

Exotropia — COMPLETE Flashcards

1
Q

Exophoria decompensates gradually to…

A

IXT and then eventually CXT

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2
Q

TRUE/FALSE: XT has a genetic/familial component

A

TRUE

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3
Q

Infantile XT onset

A

Before 1 yr

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4
Q

Non-Infantile XT onset

A

1.5 - 8 yrs

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5
Q

Prevalence of XT, compared to ET

A

ET>XT
(XT: 1/4 of ET)

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6
Q

Describe the RE of XT patients

A

Vary just as much as general population

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7
Q

General Symptoms of XT (2)

A
  1. Close one eye c sun exposure
  2. Head turn
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8
Q

Symptoms of CXT

A

Usually asymptomatic
Complaints typically cosmetic

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9
Q

Symptoms of IXT (3)

A
  1. Ocular discomfort (e.g. eyes pullin, HAs)
  2. Blur
  3. Diplopia

if asymptomatic, likely suppression or task avoidance

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10
Q

Differential Diagnosis of XT (6)

A
  1. Pseudo-XT
  2. CN 3 Palsy (c MR weakness)
  3. Orbital Disease (Medial Wall Tumor)
  4. MG (affecting MR)
  5. Duane Type 2 (bc can’t aDduct)
  6. Consecutive XT
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11
Q

Size of Micro-XT

A

1-5 PD

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12
Q

Size of Small-XT

A

6-20 PD

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13
Q

Size of Moderate-XT

A

21-40 PD

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14
Q

Size of Large-XT

A

> 40 PD

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15
Q

Vision Therapy is the treatment of choice for pts with ______ PD of XT

A

25 or less

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16
Q

What is more common: CXT vs IXT

A

IXT

CXT is very rare

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17
Q

DEXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation

A

25%
More Than

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18
Q

BXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation

A

50%
Equal to

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19
Q

CIXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation

A

25%
Less Than

20
Q

Describe the AC/A in a DEXT

A

HIGH

Remember: the distance is wayyy more than near, so each D of accommodation accounts for a lot of convergence

21
Q

Why are patients often misdiagnosed as Pseudo-DEXT?

A

Fusional Vergence Spasm

22
Q

How do you differentiate between a DEXT and Pseudo XT

A

Patch one eye for 30 min to break fusional vergence spasm, retest near CT. If near doesn’t change (still smaller than distance), True DEXT. If changes from initial measurement (becomes more equal to distance deviation), PseudoXT/BXT

23
Q

If XT non-comitant, expect…

(etiologies)

A

Trauma (obstetric, blunt trauma, etc.), muscle anomalies, or pathology (vascular, neoplasm, viral, or chronic)

24
Q

Most common etiologies for adult onset XT

A
  1. Trauma
  2. Vascular
  3. Neoplasm
25
Q

Most common etiologies for childhood onset XT

A
  1. Congenital
  2. Trauma
  3. Acute Viral Infection
26
Q

Typical age of onset for XT

A

18-28 months

27
Q

Intermittent divergent position is common in early infancy, but stabilizes by _____ months

A

2-4 months

28
Q

Most frequently seen sensory anomaly in XT patients

A

Suppression

29
Q

Which of the sensory anomalies is the most limiting?

A

Amblyopia

30
Q

Post-Surgical XT vs. Consecutive XT

A

Post-Surgical: uncorrected XT
Consecutive: over-corrected ET

31
Q

Why are Consecutive XTs difficult to treat?

A

Usually have Paradoxical Anomalous Correspondence

32
Q

Why is pre-surgical convergence therapy controversial?

A

Some surgeons think it can overcorrect XT (to ET)

33
Q

What is the tolerance level for a patient > 10 yr old?

A

1% of the time

34
Q

What is the tolerance level for a patient < 10 yr old?

A

10% of the time, without losing visual skills

35
Q

True/False: The larger the deviation of XT, the more frequent the intermittent episodes

A

TRUE

36
Q

Best possible optical correction provides ______ for binocular vision

A

Sensorimotor stimulation

37
Q

Why is undercorrecting hyperopia/overcorrecting myopia sometimes used as an IXT treatment?

What are the drawbacks of this treatment?

A

Stimulates convergence

Increases risk of myopic shift :(

38
Q

T/F: Overminusing treatment for IXT does not persist after being weaned off of overcorrection.

A

TRUE; effect wears off
(overminus therapy may be limited)

39
Q

What is the purpose of PT occlusion for XT treatment?

A

Disrupt suppression and create diplopia awareness

40
Q

Explain how increased instances of diplopia can promote alignment

A

Increased diplopia —> stimulates PFV for fusion —> promotes alignment

41
Q

What demographic of XT patients can benefit most from PT occlusion as part of their therapy?

A

Patients too young for VT or during early VT to break suppression

42
Q

Which type of XT is difficult to treat with surgery?

A

CIXT

43
Q

What is considered cosmetic success after XT surgery?

A

ET or XT < 15 PD

44
Q

What is considered functional success after XT surgery?

A

Constant tropia < 10 PD w/ peripheral fusion or small residual IXT

45
Q

Which treatment plan has the best outcome for XT?

A

Surgery + VT

46
Q

What is the “glue” that prevents post-surgical drift?

A

Sensory fusion

X. Strabismus (8 decks)

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