Exotropia — COMPLETE Flashcards
Exophoria decompensates gradually to…
IXT and then eventually CXT
TRUE/FALSE: XT has a genetic/familial component
TRUE
Infantile XT onset
Before 1 yr
Non-Infantile XT onset
1.5 - 8 yrs
Prevalence of XT, compared to ET
ET>XT
(XT: 1/4 of ET)
Describe the RE of XT patients
Vary just as much as general population
General Symptoms of XT (2)
- Close one eye c sun exposure
- Head turn
Symptoms of CXT
Usually asymptomatic
Complaints typically cosmetic
Symptoms of IXT (3)
- Ocular discomfort (e.g. eyes pullin, HAs)
- Blur
- Diplopia
if asymptomatic, likely suppression or task avoidance
Differential Diagnosis of XT (6)
- Pseudo-XT
- CN 3 Palsy (c MR weakness)
- Orbital Disease (Medial Wall Tumor)
- MG (affecting MR)
- Duane Type 2 (bc can’t aDduct)
- Consecutive XT
Size of Micro-XT
1-5 PD
Size of Small-XT
6-20 PD
Size of Moderate-XT
21-40 PD
Size of Large-XT
> 40 PD
Vision Therapy is the treatment of choice for pts with ______ PD of XT
25 or less
What is more common: CXT vs IXT
IXT
CXT is very rare
DEXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation
25%
More Than
BXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation
50%
Equal to
CIXT accounts for ___% of XT’s and Distance Deviation is ____ (less than, more than, equal to) Near Deviation
25%
Less Than
Describe the AC/A in a DEXT
HIGH
Remember: the distance is wayyy more than near, so each D of accommodation accounts for a lot of convergence
Why are patients often misdiagnosed as Pseudo-DEXT?
Fusional Vergence Spasm
How do you differentiate between a DEXT and Pseudo XT
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
If XT non-comitant, expect…
(etiologies)
Trauma (obstetric, blunt trauma, etc.), muscle anomalies, or pathology (vascular, neoplasm, viral, or chronic)
Most common etiologies for adult onset XT
- Trauma
- Vascular
- Neoplasm
Most common etiologies for childhood onset XT
- Congenital
- Trauma
- Acute Viral Infection
Typical age of onset for XT
18-28 months
Intermittent divergent position is common in early infancy, but stabilizes by _____ months
2-4 months
Most frequently seen sensory anomaly in XT patients
Suppression
Which of the sensory anomalies is the most limiting?
Amblyopia
Post-Surgical XT vs. Consecutive XT
Post-Surgical: uncorrected XT
Consecutive: over-corrected ET
Why are Consecutive XTs difficult to treat?
Usually have Paradoxical Anomalous Correspondence
Why is pre-surgical convergence therapy controversial?
Some surgeons think it can overcorrect XT (to ET)
What is the tolerance level for a patient > 10 yr old?
1% of the time
What is the tolerance level for a patient < 10 yr old?
10% of the time, without losing visual skills
True/False: The larger the deviation of XT, the more frequent the intermittent episodes
TRUE
Best possible optical correction provides ______ for binocular vision
Sensorimotor stimulation
Why is undercorrecting hyperopia/overcorrecting myopia sometimes used as an IXT treatment?
What are the drawbacks of this treatment?
Stimulates convergence
Increases risk of myopic shift :(
T/F: Overminusing treatment for IXT does not persist after being weaned off of overcorrection.
TRUE; effect wears off
(overminus therapy may be limited)
What is the purpose of PT occlusion for XT treatment?
Disrupt suppression and create diplopia awareness
Explain how increased instances of diplopia can promote alignment
Increased diplopia —> stimulates PFV for fusion —> promotes alignment
What demographic of XT patients can benefit most from PT occlusion as part of their therapy?
Patients too young for VT or during early VT to break suppression
Which type of XT is difficult to treat with surgery?
CIXT
What is considered cosmetic success after XT surgery?
ET or XT < 15 PD
What is considered functional success after XT surgery?
Constant tropia < 10 PD w/ peripheral fusion or small residual IXT
Which treatment plan has the best outcome for XT?
Surgery + VT
What is the “glue” that prevents post-surgical drift?
Sensory fusion
