X(T)
No single table for intermittent exotropia mm correction
XT <> X(T)
•pt have exophoria that is sometimes controlled
•pt have
•central and peripheral fusion are intact when the eyes are straight
•steropsis is nl when eyes are straight
•suppression and ARC can compensate when XT
•if XT becomes contant will lose fusion
•congenital xt patients have poor binocular potential
CHILDREN
•suppresion mechanism active
•potential for amblyopia
ADULTS
•diplopia
•loss of peripheral vision
PHASES OF XT
•1 X at distance, ortho near
•2 X(T) at distance, X at near
•3 XT at distance, X(T) at near
•4 XT at distance and near
CONTROL OF XT
•good: xt manifest only after cover testing. resumes fusion without a blink
•fair: xt manifest after cover testing. resumes fusion with a blink
•poor: xt spontaneously manifest
DEFINITIONS
•tenacious proximal fusion - vergence after-effect that does not dissipate c brief cover test, need to cover eye much longer
•outdoor sensitivity - XT is larger when looking further away
•AC/A ratio: •-2.00 test at distance •+3.00 test at near p monocular occlusion
BURIAN'S CLASSIFICATION
1 basic type
2 divergence excess type
3 pseudo-divergence excess type
4 convergence insufficiency type
KUSHNER'S CLASSIFICATION
NO WAY I'M COPYING this
CONCEPTS
•tenacious proximal fusion is good
•high AC/A ratio is bad
•convergence insufficiency is bad (low AC/A), where XT greater at near than distance
•basic type X(t) may require higher surg doses
•far distance may reveal more x(t), operate for largest seen
•watch out for lateral incomitance (could overcorrect for side vision)
•try not to overcorrect adults
•try not to undercorrect kids