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456 Theory and Practice of Squint and Orthoptics
because of undisturbed attachment of the
intermuscular septum to the tendon. It is
reported that this retained action of superior
oblique avoids the postoperative complication
of torsional diplopia.
2. Temporal approach is preferred in all other
indications, especially when bilateral tenotomy
is to be performed, because of the following
advantages:
• Exact measurement of the site of transaction
of the tendon can be obtained. This allows
bilateral symmetric results.
• Complications like blepharoptosis and
superior rectus weakness known with nasal
approach are almost eliminated by temporal
approach.
• Occurrence of transient Brown's syndrome
has been reported following nasal but not with
temporal approach.
• Temporal approach is technically easier than
the nasal approach. However, injury to the
superior temporal vortex vein is obviously a
potential hazard of the temporal approach.
Fig. 15.16 Surgical technique of nasal approach for
superior oblique tenotomy.
septum is considered better for treating Brown's
syndrome. Since by this technique, the superior
oblique is weakened but some action is retained
TECHNIQUES OF OTHER WEAKENING
PROCEDURES FOR SUPERIOR OBLIQUE
1. In general, temporal approach is preferred over
the nasal approach for superior oblique
weakening procedures.
2. Initial steps up to the exposure of the tendon
are similar to those described for superior
oblique tenotomy.
3. Final steps for different weakening procedures
are as follows:
i. In recession, the superior oblique tendon is
reinserted near the nasal border of superior
rectus muscle, about 4 mm posterior to its
insertion.
ii. In anteropositioning, the superior oblique
tendon is further anteriorized as compared
to recession.
iii. In translational recession, the anterior point of
superior oblique reinsertion is 4 mm nasal
from the superior rectus and 12 mm posterior
from the limbus. The advantage of the
translation recession is that it prevents the
limitation of depression in abduction which
occurs with recession or anteropositioning.
Principles of Non-Surgical and Surgical Management of Strabismus
457
Fig. 15.17 Surgical technique of superior oblique tuck.
iv. In superior oblique expander technique some
surgeons insert 2 or 2.5 mm silicon tube
(or retinal band no. 240) in between the cut
ends of the superior oblique tendon 3 mm
nasal to the nasal border of superior rectus
muscle.
v. Posterior tenotomy of superior oblique (PTSO).
This operation is based on the observation
that posterior fibres of superior oblique
account for its vertical action. So tenotomy
of the posterior fibres of the superior oblique
is performed for a selective weakening of its
depressor action.
SUPERIOR OBLIQUE STRENGTHENING
PROCEDURES
SUPERIOR OBLIQUE TUCK
Indications
1. In superior oblique paresis, the tucking
procedure helps in enhancing effect.
2. In DVD, superior oblique tucking with or
without inferior oblique weakening has been
advocated.
Surgical technique
1. Initial steps up to exposure of the superior
oblique tendon are similar to those described
for temporal approach for superior oblique
tenotomy (see page 454 and Fig. 15.15A and B).
2. Tucking procedure. After isolating, the tendon
is transferred from the muscle hook to a Burch
tendon tucker or its von Noorden modification
(Fig. 15.17A). The tendon is then lifted upward
and pulled taut by turning the screw of the
handle of the tendon tucker (Fig. 15.17B). After
a sufficient (12–14 mm) tuck has been created
on the tucker, two 5-0 Mersilene sutures are
placed near the base of tuck (Fig. 15.17C). The
sutures are secured and the tucker removed.
Previously most of the surgeons used to secure
the tip of the tuck to the sclera in the direction
458 Theory and Practice of Squint and Orthoptics
of the original plane of the tendon by an
additional suture. However, an inadvertent
anterior pull on the tendon during this
manoeuver may decrease the vertical effect of
the operation and cause pseudo-Brown's
syndrome. Therefore, many surgeons prefer not
to fasten the tucked portion to the sclera
(Fig. 15.17D).
3. Forced duction test is performed in the end to
determine the degree of restriction when
elevating the adducted eye. The tuck is
considered adequate when mild elastic
restriction is felt. If a severe restriction is
encountered, the tucking should be undone
followed by a lesser amount of tucking.
4. Conjunctival closure is done with one or two
7-0 Vicryl sutures.
Note. A transient postoperative limitation of
elevation of adducted eye (pseudo-Brown's
syndrome) is a common phenomenon after
superior oblique tucking. Rarely a permanent
Brown's syndrome may also occur.
HARADA-ITO PROCEDURE
The Harada-Ito procedure is a selective
strengthening procedure for anterior fibres of
the superior oblique muscle. This procedure
essentially consists of anterior and lateral
displacement of the anterior fibres of the muscle
resulting in an advancement of its insertion
around the equator by several millimetres. This
operation is based on the idea that the anterior
fibres of the tendon are selectively concerned
with the torsional action of the superior oblique
muscle and that strengthening of these fibres
will enhance the incyclotropic effect thereby
correcting the excyclotropia.
Indications
This procedure has been reported to be useful
in patients with bilateral or unilateral superior
oblique palsy for correcting an excyclotropia of
10° or more but without significant primary
position vertical deviation.
Surgical technique
1. Initial steps up to exposure of the superior
oblique tendon are same as described for
superior oblique tenotomy (Fig. 15.15A
and B).
2. Anterior and lateral displacement of the anterior
fibres of superior oblique tendon is carried out, after
meticulous isolation of the tendon, by any of the
following techniques:
i. Conventional Harada-Ito technique. A 5-0
Mersilene (non-absorbable) suture singlearmed is passed through the anterior half of
the tendon fibres and secured firmly with a
triple knot (Fig. 15.18A). The needle is then
passed through the sclera at a point located
3 mm temporal and anterior to the insertion
(Fig. 15.18B). At this juncture, secure tying
of the suture over its scleral fixation will pull
the anterior fibres of the tendon anteriorly
and laterally.
ii. Fells modification over Harada-Ito technique. A
visual estimate of half the width of superior
oblique tendon is made and its insertion is
split parallel to its tendinous fibres. A single
6-0 Vicryl suture is placed at the edge of the
anterior half of the insertion. The anterior
half of the tendon is then disinserted and
reattached to the sclera at a point where the
continuation of the lines of insertion of the
superior and lateral recti meet. A second
single-armed 6-0 Vicryl suture is used to
secure the posterior point of the splitted and
anteriorly transported anterior half of the
tendon approximately 6 mm directly behind
this point (Fig. 15.18C).
iii. Harada-Ito procedure with adjustable suturing
technique. Some surgeons have suggested the
use of adjustable sutures after splitting the
tendon as in Fells' modification. However,
not much advantages are associated with this
modification.
3. Conjunctival closure is performed with one or
two of 7-0 Vicryl sutures.
MUSCLE TRANSPOSITION PROCEDURES
Muscle transposition procedures essentially
involve moving the extraocular muscles out of
their original planes of action. Such procedures
are generally reserved for treatment of paralytic
strabismus. The usual situations in which these
procedures are used include paralysis of cranial
nerves III and VI as well as double elevator
palsy. The muscle transposition procedures are
Principles of Non-Surgical and Surgical Management of Strabismus
Fig. 15.18 Surgical technique of Harada-Ito procedure
(for explanation, see text).
also useful in A- and V-patterns, cyclodeviations and small vertical and horizontal
deviations. A few commonly performed muscle
transposition procedures are described here.
459
MUSCLE TRANSPOSITION PROCEDURES IN
TREATMENT OF A- AND V-PATTERNS
1. Vertical transposition of the horizontal rectus
muscles and horizontal transposition of the
vertical rectus muscles has been recommended
for correcting A- and V-patterns.
2. Surgical technique of these procedures is
similar to recession and resection procedures for
rectus muscles except that muscles are
reinserted by shifting the insertion between half
or one full muscle width as per requirement.
Important point to be noted is that even after
shifting, the muscle should be reinserted parallel
to the limbus.
MUSCLE TRANSPOSITION PROCEDURES FOR
TREATMENT OF CYCLODEVIATIONS
1. Horizontal transposition of vertical rectus
muscles and vertical transposition of horizontal
rectus muscles has been recommended for:
• Correction of cyclotropia, and
• Correction of compensatory head tilt to one
shoulder in patients with a nystagmus having
null zone in tertiary gaze position.
2. The direction in which the vertical and
horizontal rectus muscles be transposed to cause
incycloduction or excycloduction of each eye is
as follows:
• To cause incyclodeviation, the superior rectus
should be shifted temporally and inferior
rectus nasally (Fig. 15.19).
• To produce excyclodeviation, superior rectus
should be shifted nasally and inferior rectus
temporally.
• To produce incyclodeviation, the medial
rectus should be shifted upward and lateral
rectus downward (Fig.15.20).
• To cause excyclodeviation the medial rectus
should be shifted downward and lateral
rectus upwards.
3. Surgical technique of these procedures is
similar to recession and resection procedure for
these muscles, except that muscles are reinserted by shifting the insertion by one-half or
one full muscle thickness, as per requirement.
Even the shifted reinsertion should be parallel
to limbus.
460 Theory and Practice of Squint and Orthoptics
Fig. 15.19 Temporal transposition of superior rectus tendon
and nasal transposition of inferior rectus tendon to produce
incyclodeviation.
Fig. 15.20 Upward transposition of medial rectus and
downward transposition of lateral rectus to produce
incyclodeviation.
MUSCLE TRANSPOSITION PROCEDURES FOR
PARALYTIC SQUINT
• It has been reported that the muscle trans-
position procedures are useful in paralytic
squint by their mechanical effect and not by
any innervational adjustment.
• The muscle transpositions are useful in
paralytic squint, only if there is no restriction
to passive movements of the eyeball in the
paretic field of gaze. Therefore, if forced
duction test reveals any restriction, it should
be removed first by a maximal recession of
the contractured antagonist of the paretic
muscle with or without conjunctival recession
depending upon the need.
• The commonly performed muscle trans-
position procedures for paralytic squint are
as follows:
– Knapp's procedure
– Hummelsheim procedure
– Jensen's procedure
– Transposition of superior oblique tendon
– Transposition of lateral rectus muscle
Knapp's procedure
Indication
Knapp procedure consists of transposition of the
insertion of medial and lateral recti to that of
superior rectus (in patients with double elevator
palsy) or inferior rectus (in patients with double
depressor paralysis).
Surgical technique
1. Conjunctival incision consists of a superior or
inferior limbal peritomy of approximately 210°
depending upon the indication.
2. Exposure of the muscles. The medial and lateral
recti and either superior or inferior rectus, are
exposed as described in recession for rectus
muscles.
3. Disinsertion of horizontal recti. After meticulous
isolation, as in recession procedure, 6-0 Vicryl
sutures are passed near the insertion of medial
and lateral recti and the muscles are disinserted
from the globe.
4. Transposition of the horizontal recti. A
Desmarre's retractor is used to hold the
conjunctiva out of the surgical field and the
medial and lateral recti are reattached to the
globe at each corner of the insertion of either
superior rectus (in patients with double elevator
palsy (Fig. 15.21) or inferior rectus (in patients
with double depressor palsy).
5. Conjunctival closure is done in the end of
surgery.
Jensen's procedure
Indication
Jensen's procedure is indicated in patients with
complete paralysis of lateral rectus muscle. It
Principles of Non-Surgical and Surgical Management of Strabismus
Fig. 15.21 Knapp's procedure for double elevator palsy.
461
Further, one must ensure that sutures are tied
loosely enough to prevent strangulation and
necrosis of the muscle.
4. Recession of the medial rectus. It is imperative
that Jensen's procedure should always be
combined with a maximal recession of the
ipsilateral medial rectus muscle with or without
conjunctival recession to obtain successful
results. The recession is performed as usual. To
prevent anterior segment ischaemia, especially
in older individuals, the recession of medial
rectus and conjunctiva should be performed at
least 4 to 5 months prior to the actual Jensen's
procedure.
5. Conjunctival closure is done as usual.
consists of transposition of half thickness
muscle of superior and inferior recti to the lateral
rectus at the level of equator.
Surgical technique
1. Conjunctival incision consists of 180° peritomy
performed at the temporal half of the limbus.
2. Exposure of the muscles. The lateral, superior
and inferior recti are meticulously exposed
beyond the equator as in recession procedure.
3. Transposition of the muscles. The tendons of
superior, lateral and inferior rectus muscles are
isolated and split posteriorly for approximately
8 mm with the help of a muscle hook. Then the
temporal halves of the superior and inferior recti
are joined with the corresponding superior and
inferior halves of the lateral rectus over the
equator using 5-0 Mersilene suture (Fig. 15.22).
It is important to note that at least one branch of
the anterior ciliary vessel should remain in the
nasal segment of each of the vertical recti that
are not incorporated in the muscle union.
Hummelsheim procedure
Indication
This procedure is indicated in complete 6th
nerve palsy in which any contracture of the
medial rectus has been eliminated by a previous
or simultaneous medial rectus recession.
Surgical technique
Hummelsheim procedure basically consists of
total transplant of the superior and inferior
rectus muscles to the insertion of the lateral
rectus muscle (Fig. 15.23). The surgery is
performed through a 180° temporal peritomy
and the technique is essentially similar to
Knapp's procedure.
Transposition of superior oblique tendon
Indication
Transposition of superior oblique tendon to the
insertion of medial rectus muscle is indicated
Fig. 15.22 Jensen's procedure for lateral rectus palsy.
Fig. 15.23 Surgical technique of Hummelsheim procedure
for lateral rectus muscle palsy.
462 Theory and Practice of Squint and Orthoptics
in patients with third cranial nerve palsy. This
procedure is always combined with a maximal
recession (10–12 mm) of the lateral rectus
and resection (8–9 mm) of the medial rectus
muscle.
Surgical technique
Superior oblique tendon transposition is
performed by nasal approach. In this classical
approach, superior oblique tendon is exposed
as described for nasal approach for tenotomy
(see page 455). A small closed mosquito
haemostat is then slid along the tendon until its
tip enters the pulley of the trochlea. The tendon
is freed after fracturing the pulley by just
opening the hemostat. The tendon is then
shortened by 10–12 mm and is sutured to the
sclera near the superior border of the medial
rectus muscle. Results of this procedure in
improving the adduction are not always
encouraging.
Transposition of lateral rectus muscle
Some lateral rectus transposition procedures
which have been recommended by some
workers, for surgical management of third nerve
palsy include:
• Inferior nasal transposition of lateral rectus
• Lateral rectus transposition to the nasal pole
of superior rectus muscle
• Medial transposition of Y-split lateral rectus
muscle
Periosteal fixation of extraocular muscles
Medial rectus orbital wall (periosteal) fixation
Medial rectus orbital wall (periosteal) fixation
with the help of non-absorbable 5-0 Mersilene
sutures through the retrocaruncular or skin
approach (using DCR incision) has also been
described for surgical management of third
nerve palsy. However, it shows limited
effectiveness.
Lateral rectus orbital (periosteal) fixation
Lateral rectus orbital (periosteal) fixation after
disinserting the LR combined with 8–9 mm
resection of MR has been reported to show
reasonably good results in patients with third
nerve palsy.
COMPLICATIONS OF EXTRAOCULAR
MUSCLE SURGERY
Complications of extraocular muscle surgery are
inevitable for any regularly operating strabismus surgeon. They vary in severity and
frequency. Complications of extraocular muscle
surgery, their prevention and management can
be discussed under following headings:
• Complications of anaesthesia
• Intraoperative complications
• Postoperative complications
COMPLICATIONS OF ANAESTHESIA
Undoubtedly, general anaesthesia has become
very safe in the recent days, however, it is never
entirely free from danger. Even deaths due to
anaesthesia to the tune of 2 per 10,000 have been
reported during strabismic surgery. The
potentially dangerous complications reported
are as follows:
1. Cardiac arrest. Such a life-threatening
complication may occur during operation or
during recovery period. So a careful and
meticulous monitoring is very important.
Further, the ophthalmologist must be aware of
the updated means of managing such a
catastrophy and should be in a position to
actively help the anaesthetist during the crisis
hours. A ready tray of emergency drugs filled
in syringes is mandatory in the operation
theatre.
2. Malignant hyperthermia. It is a comparatively
rare but again a life-threatening complication
of anaesthesia.
Prevention. In some families susceptibility to this
condition is inherent and is apparently
autosomal dominant. Therefore, careful history
and constant monitoring of the rectal temperature
especially in predisposed patients may help in
avoiding the crisis. Use of succinylcholine
should be better avoided, as chances of
malignant hyperthermia are comparatively
more, when this drug is used.
Management. The condition is diagnosed by the
occurrence of tachycardia, arrhythmia, rapidly
rising temperature, acidosis and shock. The first
sign of malignant hyperthermia is muscular
Principles of Non-Surgical and Surgical Management of Strabismus
463
rigidity and hyperthermia is a late sign. Once
diagnosed, it should be treated energetically to
prevent death by taking following measures:
• Immediately stop anaesthesia
• Provide care and surface cooling
• Correct metabolic acidosis
• Intravenous use of the drug dantrolene
sodium is quite effective incontrolling
malignant hyperthermia.
3. Hepatic porphyria and suxamethonium
sensitivity are other genetic disorders which can
cause serious complications during and after
general anaesthesia.
4. Oculocardiorespiratory reflexes. The occur-
rence of oculocardiorespiratory reflexes is
related to extraocular muscle manipulation and
thus to be precise are operative complications.
However, since they occur more frequently with
general anaesthesia and are to be basically
managed by the anaesthetist so they are
discussed here. The oculocardiorespiratory
reflexes include oculocardiac reflex, oculorespiratory reflex and oculodepressor reflex.
• Oculocardiac reflex (OCR) refers to slowing of
heart rate and/or disturbances in cardiac
rhythm resulting from manipulation of
extraocular muscles. It was first described by
Aschner in 1908 and since then an abundant
work has been done on various aspects of OCR.
Its reported incidence varies from 32 to 90%.
• Oculorespiratory reflex (ORR), also first
described by Aschner, refers to slowing of
respiration on extraocular muscle traction.
• Oculodepressor reflex (ODR) has recently been
described by Khurana et al. to denote the
significant fall in blood pressure observed
during extraocular muscle traction. One might
expect the cardiac output and, therefore, arterial
blood pressure to fall in the presence of
significant cardiac slowing due to oculocardiac
reflex (OCR). However, the significant
hypotension observed by the authors even after
abolition of OCR by vagotomy, atropine and
glycopyrronium have confirmed ODR to be
distinct and independent of OCR.
• Prevention of OCR, ORR and ODR becomes
imperative during squint surgery since the
retrobulbar injection of 2% xylocaine blocks the
afferent pathway of all three reflexes, its use has
been recommended, even when the surgery is
performed under general anaesthesia. In
addition, intravenous atropine or glycopyrronium should also be used to block the efferent
pathway of OCR. Further, controlled ventilation
must be preferred to spontaneous breathing at
least before, after and during muscle traction.
5. Succinylcholine-induced apnoea. Succinyl-
choline-induced apnoea may occur in children
who are on miotics, echothiophate iodide. So it
is most important to not to schedule surgery
until the miotics have been discontinued for a
period of at least 2–3 weeks, thus avoiding this
problem. However, this problem can also occur
due to primary cholinesterase deficiency which
is an autosomal recessive condition reported to
affect some individuals. These patients can have
prolonged apnea following succinylcholine
administration in the absence of prior treatment
with miotics. Making specific queries of unusual
perianaesthetic problems in general, family
history may sometimes be helpful in anticipating it.
6. Complications related to peribulbar anaesthesia
• Muscle trauma
• Retrobulbar haemorrhage
• Globe perforation
• Myotoxicity
INTRAOPERATIVE COMPLICATIONS
1. Conjunctival complications
• Buttonholing of conjunctiva, irregular extension
of conjunctival incision and inaccurate closure
of conjunctival incision are commonly
encountered in squint surgery. Conjunctival
chemosis and subconjunctival haemorrhage
are seen in the majority of the cases after
surgery.
• Inadvertent advancement of plica semilunaris.
• Overhanging or retraction of conjunctival at the
limbus, and
• Prolapse of tenons are infrequently seen after
surgery.
Note: Use of marking pen to mark the incision
and use of stay sutures at cut edges help in
accurate approximation of wound margin and
can prevent many of these complications.
464 Theory and Practice of Squint and Orthoptics
2. Corneal complications
Corneal abrasion: Corneal abrasions as a result
of instrumentation during strabismus surgery
are common and are managed with lubricating
drops and eye patch depending on the extent of
corneal involvement.
3. Haemorrhage
• Mild surgical haemorrhage from subconjunctival
vessels is routine and is not preventable.
Rarely wet field cautery may be needed to
control bleeding from these vessels.
• A moderately excessive haemorrhage may occur,
if the muscle is cut inadvertently, which is
preventable if dissection is carried out
meticulously. Compression for a while or wet
field cautery may be needed to control it.
• A profuse venous bleeding indicates vortex vein
rupture. It is not an uncommon complication
and is caused by careless dissection or
anomalous location of vortex veins. The vortex
vein, i.e. most easily ruptured is the inferior
temporal vortex veins. Rupture often occurs
during lateral rectus and inferior oblique
surgery. The best way to handle this
complication is that no attempt should be
made to try to clamp the vortex vein, since
clamping may result in further damage.
Generally speaking, there are no postoperative
complications from a tear in a vortex vein
during surgery.
4. Lost and slipped muscle
• Lost muscle is a serious complication of
extraocular muscle surgery.
• Medial rectus is the most frequently lost
muscle, because of its fewer attachments to
other muscles and ligaments. For instance,
inferior rectus is checked in its retraction into
the orbit by Lockwood's ligament, superior
rectus by its attachment to levator and lateral
rectus by its association with inferior oblique
muscle.
• Lost muscle can occur intraoperatively or in
immediate postoperative period.
• Lost muscle occurs because of following
reasons:
– Inadvertent transaction of the muscle.
– Slipping of the muscle from the suture.
– Slipping of the muscle from the resection
clamp.
• Prevention for lost muscle includes, a gentle,
meticulous and careful dissection, secure
placement of sutures at preferred site and
proper application of resection clamp.
• Intraoperative muscle loss should be managed
as follows:
– If slippage occurs during a recession
procedure, flooding the area with irrigation
solution may usually reveal the cut end of a
tendon as a glistening white structure. If so,
the muscle can be easily retrieved and
resutured.
– If the slippage occurs during resection
procedure or when the above measures do
not help in finding the lost muscle in
recession, one should gently examine the
Tenon's capsule with forceps in both hands
used end over end. The tunnel in the Tenon's
capsule in which the muscle course can be
searched by this manoeuvre. Then one can
reach back through the tunnel and grasp the
muscle with forceps and pull forward. The
sutures are placed and the procedure is
carried out as planned.
– If the muscle cannot be found, the best
choice is to perform a maximal recession on
the antagonist muscle along with a recession
and Faden procedure on the yoke muscle of
the lost muscle. If alignment in the primary
position cannot be obtained by this, then
one should perform a muscle transposition
procedure. In this procedure, the adjacent
halves of the two closest rectus muscles are
transposed to the scleral insertion site of the
lost muscle.
• Postoperative muscle lost occurs due to slippage
of muscle not secured properly to the sclera.
Possibility of a slipped muscle probably exists
until the 5th or 6th postoperative day, when
granulation tissue has sufficiently attached the
muscle to sclera. It is diagnosed by following
observations:
– Patient will be unable to move the eye into
the field of action of lost muscle.
– Palpebral fissure will widen as the patient
attempts to move the eye into the field of
action of lost muscle.
– Patient will either have a marked over-
correction or a larger deviation than was
Principles of Non-Surgical and Surgical Management of Strabismus
465
present before the operation, depending
upon the muscle lost.
Management of postoperative slipped muscle
is similar to that of intraoperative lost muscle.
It is most important to note that exploration
should be carried out as early as possible, since
as time passes, finding the muscle becomes
progressively more difficult.
5. Scleral complication: Perforation of eyeball
Scleral perforation with or without perforation
of choroid or choroid and retina, during
extraocular muscle surgery may occur in one of
two ways:
i. During cutting of the muscle insertion, sometimes
scleral laceration, with or without damage to
underlying tissue, may occur. This complication
is most likely to occur, if the muscle is under
considerable traction with the hook and the
sclera is very thin especially in patients
with high myopia and/or hereditary connective
tissue disease. It should be managed as
below:
• Scleral perforation should be sutured with
10–0 nylon suture. If scleral hole is large, a
preserved scleral patch or a silicone patch may
be applied to the area. If small and is located
directly at the muscle insertion during
resection procedure; the resected muscle can
be sutured over the defect.
• Pupil should be dilated and the retina should
be examined with the indirect ophthalmoscope.
• Prophylactic transcleral cryotherapy is
recommended around the site of injury. When
a retinal perforation is discovered, careful
postoperative follow-up examinations with
indirect ophthalmoscopy should be performed.
ii. During placement of needles for reinsertion of the
muscle, chances of scleral and chorioretinal
perforation are more than during cutting of the
muscle. In fact, this complication may occur
more frequently than is usually recognized or
admitted. Undoubtedly, the rate of perforations
has decreased since the introduction of spatula
needle. It is recommended that even on slightest
doubt of perforation with needle, the pupil
should be dilated and a careful indirect
ophthalmoscopy should be carried out. If a
retinal hole is detected, it should be managed
as discussed above.
Though extremely rare, but serious complications such as endophthalmitis, retinal
detachment and phthisis bulbi have been
reported following perforations. Therefore, a
very careful watch is required for such cases.
6. Operation on the wrong muscle
Such a complication has also been reported
occasionally under following circumstances:
• By mistake (or due to absentmindedness of
the surgeon), the muscle to be resected may
be recessed and vice versa.
• In excessively rotated globe, the exact position
of the muscle may be shifted.
• During reoperation, the previously operated
muscles may in an unusual location.
• Myectomy of the inferior rectus is a possible
complication of myectomy of the inferior
oblique at its origin through an inferior culde-sac approach.
Prevention of such a complication includes:
• Exact marking of 3, 6, 9 and 12 o'clock
meridian at limbus before the conjunctival
incision is made.
• To use the identifying check marks of the
various muscles such as close association of
the:
– Inferior oblique with lateral rectus,
– Superior oblique with superior rectus, and
– Inferior oblique with inferior rectus.
7. Inadvertent injury to the other muscles
Inadvertent injury to the following muscles has
been reported during strabismus surgery:
i. Partial or complete disinsertion of the inferior
oblique may occur during lateral rectus surgery. This
is because, it is extremely easy to hook part or
all of the inferior oblique tendon, when passing
a hook under the lateral rectus muscle. To
prevent this complication, it is recommended
that the lateral rectus be doubly hooked and that
the area be carefully inspected to make sure that
the inferior oblique is not incorporated and
disinserted during the freeing of the inferior
check ligaments and inferior intermuscular
septum during a lateral rectus recession. If,
however, the inferior oblique is inadvertently
partially or completely disinserted, a suture may