Intermittent exotropia
Intermittent
exotropia is a common form of strabismus
where Patients demonstrate a duality of
behavior in that they seem to be completely
normal during orthotropic intervales and
totally ‘turned off’ during periods of
manifest exodeviation. In contrast to the exophoria, patients with
intermittent exotropia demonstrate a
manifest deviation part of the time.
These patients are classified into four
types on the basis of in what field or
distance of gaze the deviation is greater :
I. Basic type : The exodeviation is the same at distance and at
near.
II. Divergence excess type :
The distance exodeviation is greater than the
near deviation by 15 prism diopters.
III. Convergence
insufficiency type : The near exotropia is
greater than the far deviation by 15 prism
diopters.
IV. Simulated divergence excess type
The surgical treatment of intermittent exotropia
presents some philosophical problems. These
patients have a lot going for them before
anything is done. Vision is usually equal
and normal in each eye, sensory fusion with
stereopsis and motor fusion amplitudes are
present, and versions and ductions are
intact. In other words, the ‘good’
intermittent exotropia patient has no
problems, if there is any, it always starts
after surgical interference !!
This patient represents a straightforward case of intermittent exotropia
basic type since the far fixation is only
10 PD larger than the near fixation.
There is no urgent need for surgery, but on the
other hand it could be done at any time. A
bilateral lateral rectus recession of 7.0 mm
would be sufficient.
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