Strabismus - Fundamentals of Clinical Ophthalmology.pdf

THERAPY OF STRABISMUS
to maintain fusion in downgaze. This may mean
the patient is left with slight chin up in the
primary position. Fusion in downgaze is
important in reading and going down stairs. In a
restrictive problem like thyroid eye disease
which makes the patient orthophoric in primary
position, correcting the hypotropia by
weakening the inferior rectus is associated with a
different set of problems, including diplopia in
downgaze. In several cases, we have resorted to
combining weakening the muscle without
further altering its insertions by marginal
myotomy. This has been done as a secondary
procedure if the initial surgery was unsuccessful.
Hazards of inferior rectus recession include
recession of the lower lid. Caution must be
exercised if the inferior rectus is recessed by more
than 3 mm. If the inferior rectus is recessed more
than 3 mm, even with careful dissection of the
check ligaments, lower lid retraction will follow.
At review 1–2 months later, surgery may be
indicated using eyebank sclera grafted to the
lower end of the tarsal plate to reposition the lid
and raise the level of the lower lid.
It is important to operate when the patient is
euthyroid and the thyroid eye disease is
quiescent. Even so, recession of the inferior
rectus may be followed by conversion of the
hypotropia to hypertropia if there is involvement
of the superior rectus. Subsequent forced
duction testing will show that the superior rectus
is also involved and this can be further
confirmed with imaging.
Globe perforation
The surgeon should be alert to this possibility,
especially in the thinned area of sclera
immediately posterior to the insertion of the
muscle. The increasing popularity of hangback
sutures for medial and lateral rectus muscle
surgery should reduce the risk of perforation. If
perforation occurs with loss of vitreous, a small
area of cryotherapy should be performed
visualising the area through a dilated pupil, and
subconjunctival antibiotics at the conclusion of
the surgery may be equally wise. The risk of
retinal detachment is small; however, a retinal
surgeon should be consulted. The risk of
perforation includes endophthalmitis.
Postoperative infection
Endophthalmitis
Endophthalmitis is rare, but may occur. A
retinal surgeon should be consulted, with a
vitreous biopsy and instillation of intravitreal
antibiotics instituted as a matter of urgency.
Orbital cellulitis
Undue swelling of the upper and lower lid
with fever and pain on eye movement requires
urgent admission. Smear and blood cultures
should be performed and systemic intravenous
antibiotic should be administered.
Conjunctivitis
Topical antibiotics should be used for 1–2
weeks. Prophylaxis by instillation of half strength
povidone-iodine may also help prevent
perioperative conjunctivitis. 16,17
Tenon’s capsule inflammation
Prolapse of Tenon’s capsule into the
conjunctival wound can be associated with
inflammation. Careful closure of conjunctiva
and the use of saline will distinguish Tenon’s
from conjunctiva.
Suture granuloma and suture abscess
These may present as a tender lump and if
not resolving, should be excised preferably after
10 days of surgery. Replacement of suture is
rarely required. Allergic reactions to polyglycolic
acid sutures are rare, and more common with
catgut. Skin tests by threading the suture
through the skin will confirm this.
Epithelial conjunctival inclusion cysts
These are rare, but may reach a large size
and should be removed under the operating
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