What’s on BV – Episode 2 – How to get more from your occluder – Part 2

What do we mean by recovery?wobv_logo_125.gif

In the last episode, we saw that concomitant deviations do not have to be symmetrical, and that in the case of anisometropia, one may see an asymmetrical movement of the eyes on the alternate cover test.  This episode highlights the importance of the recovery movement seen on cover test.

In my time teaching BV in various clinical settings, it seems that the majority of people are quite happy with terminology used for manifest strabismus (tropia), whereas latent strabismus (phoria) is somewhat less well understood.

One term in particular is ‘recovery’.  When describing the characteristics of a patient’s phoria, it is common to write, for example:

‘Cover Test @ 1/3m: slight exophoria with rapid recovery’.

But what exactly do we mean by recovery?

Take for example the patient used above.  The cover test result implies that when fixating a target at 1/3m, both eyes are aligned, but on dissociation with an occluder, the covered eye deviates outwards.

As the occluder is moved to the other eye, the previously covered eye has to move inwards in order to retain fixation on the target.  This movement is simply a ‘fixation’ movement and should not be confused with recovery.

On removal of the occluder, the eyes return to their straight-ahead position, in other words, binocular single vision (BSV) is restored.  This is the recovery movement which one can therefore consider to mean ‘recovery to BSV’.  This means that observation of the eyes the instant the occluder is removed is critical in order to assess recovery.

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