Alternating Tropia
Started by nomadic123
Alternating tropias are diagnosed with a unilateral cover test.
Phorias are diagnosed using one of a number of different tests.
Yeah, it does. If you see their eye kicking in or out on unilateral it's a tropia, but if it only moves on alternating it's a phoria.
could you please give me an example. say you cover the RE, and the LE picks up fixation, then you have a tropia in the LE.
If you covered the RE, and saw no movement in the LE, then you don't have a tropia. If you then saw movement in the RE upon uncovering the RE, then you have a RE phoria.
With the alternating cover test, if you covered the RE and saw no movement and then immediately switched to cover the LE and saw movement in the RE, then you could have a phoria in the RE or an alternating tropia right? But in this case, how do you distinguish between the phoria or alternating tropia?
I hope I make sense ( sorry if that was impossible to follow)
If you covered the RE, and saw no movement in the LE, then you don't have a tropia. If you then saw movement in the RE upon uncovering the RE, then you have a RE phoria.
With the alternating cover test, if you covered the RE and saw no movement and then immediately switched to cover the LE and saw movement in the RE, then you could have a phoria in the RE or an alternating tropia right? But in this case, how do you distinguish between the phoria or alternating tropia?
I hope I make sense ( sorry if that was impossible to follow)
The alternating cover test cannot distinguish between a phoria or tropia. It can only be used to quantify the tropia or phoria.
As an aside, you are listed as an optometry student. What school do you go to?
Yes. I should have said phorias are MEASURED with a bunch of different tests.
what if you had this scenario:
when performing alternative cover test, cover RE, no LE movement = no tropia
then switch to cover LE; see RE movement inwards = either RE exophoria OR alternating constant exotropia.
then if you switch to cover RE again; 1. see no LE movement = RE exophoria
but if 2. you saw LE move in = alternating constant exotropia
is this right? if so, would this diagnose a phoria from a alternating tropia?
when performing alternative cover test, cover RE, no LE movement = no tropia
then switch to cover LE; see RE movement inwards = either RE exophoria OR alternating constant exotropia.
then if you switch to cover RE again; 1. see no LE movement = RE exophoria
but if 2. you saw LE move in = alternating constant exotropia
is this right? if so, would this diagnose a phoria from a alternating tropia?
I go to school in New Zealand by the way. The University of Auckland
if you're doing alternating CT and both eyes are moving, it's probably a phoria.
If you go back and re-check UNILATERAL CT after seeing movement with alternating, and you still see movement, that means they're a trope. (Someone feel free to fix me if I'm wrong, this has always been my weak area.) A lot of good textbooks have a flowchart of what your patient has if you see a certain type of movement.
Yes. Essentially, the only test that can differentiate between the phoria and tropia is the unilateral cover test. If you cover OD and OS turns in or out, you have a tropia. If you cover OD and OS remains still, yet when you uncover OD, OD moves, then you know it is a phoria.
I've already attempted to help the OP with the original question.
Last edited:
