Strabismus - Fundamentals of Clinical Ophthalmology.pdf

STRABISMUS
Fourth nerve palsy is common and the
majority of cases are congenital or traumatic.
The patient may not be aware of compensatory
head postures, but old photos will confirm.
If the superior oblique palsy is not congenital
or traumatic, a neurological consultation to
exclude intracranial neoplasm is mandatory.
Horizontal diplopia is usually related to sixth
nerve paresis and is obvious clinically. Trauma,
vascular disease and raised intracranial pressure
are the commonest causes. Diplopia in the older
person is sometimes ascribed to divergence
insufficiency. There may be associated symptoms
of nystagmus, vertigo or dizziness on head turn,
suggesting vertebrobasilar insufficiency. The
diplopia is often readily corrected with prisms
and may reflect underlying bilateral mild sixth
nerve palsy. It is important to consider whether
or not to investigate carotid and vertebral
circulations and the associated circle of Willis
depending on the patient’s age and possibility of
therapeutic intervention.
Horizontal diplopia may occur as a result of a
lesion in the medial longitudinal fasciculus due
to multiple sclerosis in a young adult or microvascular
disease in the older patient. An
important cause to consider is internuclear
ophthalmoplegia. The leading eye will reveal
abducting nystagmus, whilst the following eye
will show inability to adduct in horizontal gaze in
the presence of diplopia, and convergence is
usually preserved. A diverse range of disease
processes can damage the sixth nerve causing
horizontal diplopia, reflecting its long course
from the brainstem to the lateral rectus.
References
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Advances in Amblyopia and Strabismus. Transactions of
the VIIth International Orthoptic Congress, Nurnberg,
1991.
3. Pratt-Johnson JA. 18th Annual Frank Costenbader
Lecture. Fusion and suppression: development and loss.
J Pediatr Ophthalmol Strabismus 1992;29:4–11.
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Ophthalmol 1958;60:1027–35.
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