Intermittent Exophthalmos
This rare
clinical picture characterized by intermittent unilateral or
bilateralexophthalmos is caused byvaricose
dilation of the orbital veins, such as canoccur following trauma or in
Osler’s disease (polycythemia vera). Patients report protrusion of the eyeball
of varying severity. Exophthalmos is usually unilateral and is especially prone
to occur when the resistance to venous drainage is increased, as can occur when
the patient presses, bends over, screams, or compresses the vessels of the
neck. Occasionally the exophthal-mos will be associated with increased filling
of the episcleral and/or conjunc-tival vessels. The disorder can be diagnosed
in ultrasound studies using theValsalva
maneuver. A differential diagnosis should exclude a fistula betweenthe
carotid artery and cavernous sinus or an arteriovenous aneurysm, which is
usually accompanied by a dramatic clinical picture with pulsation and increased
intraocular pressure. In these clinical pictures, the ultrasound examination
will reveal generalized dilation of
the orbital veins. Surgical removal of orbital varices entails a high risk of
damaging crucial delicate neu-rovascular structures in the orbital cavity.
However, it may be indicated in rare cases such as cosmetically unacceptable
exophthalmos or where symp-toms of keratoconjunctivitis sicca occur due to
exposure that fails to respond to treatment.
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