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446 Theory and Practice of Squint and Orthoptics
Fig. 15.10 Surgical steps of recession using two-stage postoperative adjustable sutures technique.
Principles of Non-Surgical and Surgical Management of Strabismus
447
5. Closure of conjunctiva. The knot is kept exposed
by suturing the conjunctival flap on either side
of the insertion stump using bare sclera
technique of closure (Fig. 15.10C).
6. Placing of traction suture. Lastly, a traction
suture (5-0 Mersilk) may be inserted through the
superficial sclera between the limbus and the
old tendon insertion. This will act as a 'globecontrol handle' and facilitate exposure by
rotating the globe during suture adjustment. It
is important to note that at the end of the
surgery, pad and bandage is done without using
ophthalmic ointment, since it can make muscle
suture manipulation more difficult.
7. Postoperative adjustment. One has to wait for
the adjustment of suture till the anaesthetic
effect has worn off. This is variable in the
individual cases. Most surgeons prefer to do it
on the second day. The procedure is done while
the patient sits on a chair with back rest as
follows:
• Assessment of deviation. On second day, after
removal of the patch, the amount of deviation
is assessed by prism cover test. In cases of
refractive error, this is done with optical
correction. In case of diplopia, Maddox rod
is used appropriately. Two or three
measurements should be taken with 20–30
minutes interval before adjustments.
• Topical anaesthesia and separation of lids. Once
the deviation is stabilized, topical anaesthetic
drops are instilled twice or thrice into the
conjunctival sac. The lids are separated by
using a speculum. The bow knot is loosened,
by using a needle holder and tying forceps and
is adjusted accordingly (Fig. 15.10D).
• Suture adjustment. In case of overcorrection,
the muscle is pulled forward by the sutures
while the globe is fixed with help of a forceps
applied at the insertion stump (Fig. 15.10E).
In case of undercorrection, the muscle is
pushed backward. To do this, globe is pulled
with the help of traction suture or a forceps
applied at the insertion stump in the opposite
direction, e.g. temporally in case of medial
rectus recession (Fig. 15.10F) and the patient
is asked to look in the direction of field of
action of the recessed muscle. This manoeuvre
allows the muscle to slide further posteriorly.
Practically, it is easy to pull the muscle
forward rather than pushing it backward. For
this reason, most of the surgeons prefer to do
1 or 2 mm more recession than the required
amount. After the adjustment is completed the
sutures are permanently tied with a triple knot
(Fig. 15.10G).
Steps for postoperative suture adjustment with
resection
1. Initial steps up to exposure of the muscle are
same as for usual surgery.
2. Placing of sutures in the muscle. While using
adjustable sutures for resection, the sutures are
placed approximately 3 mm posterior to the
desired amount of resection. For example, if the
muscle to be resected is 5 mm, the sutures are
placed 8 mm from the insertion in a manner
similar to that for recession.
3. Resection of muscle. 8 mm of the muscle
segment is then resected as done for usual
resection.
4. Placing of sutures in the sclera. The two
needles of the double-armed suture are then
passed under the original insertion stump
similar to adjustable suture recession. The bow
knot is then tied after allowing the muscle finally
to rest 3 mm from the original insertion, thus
effectively resulting in a 5 mm resection.
5. Rest all other steps up to final adjustment
are similar to the adjustable suture surgery for
recession.
Disadvantages of adjustable suture surgery
1. Increases the total operation time during
primary surgery.
2. Requires an additional procedure.
3. A vaso-vagal attack can occur while pulling
on the muscle.
4. During adjustment, suture can break causing
a slipped muscle.
Contraindications of adjustable suture surgery
1. Children and uncooperative adult patients.
2. Variable angle of deviation like in intermittent exotropia, where the patient tries to
control the deviation.
3. Surgery involving angulation or displacement of the muscle.
4. Surgery on oblique muscles.
448 Theory and Practice of Squint and Orthoptics
MARGINAL MYOTOMY
Marginal myotomy refers to weakening of a
muscle by giving an incision partly through the
muscle margin.
Indications
The operation is most often used, when further
weakening of a maximally recessed muscle is
desired. For example, a marginal myotomy of
one of the recessed muscle can be done, if a
patient has been undercorrected following
bilateral lateral rectus recession for exotropia
or bilateral medial rectus recession for
esotropia.
Technique
1. Initial steps up to exposure of the muscle are
similar to usual recession.
2. Marginal myotomy. After the muscle has been
exposed meticulously, it is held under tension
with two large hooks. Haemostasis is obtained
by briefly crushing the tissue to be cut with
mosquito haemostats. The inferior haemostat is
applied 3–4 mm behind the insertion and the
superior haemostat is applied 3–4 mm posterior
to this (Fig. 15.11A). Marginal myotomy is then
performed with the help of tenotomy scissors,
cutting about 70% of the width of the muscle in
the crushed area (Fig. 15.11B). It is important to
note that posterior incision should always be
made before the anterior one to prevent
distortion of the muscle. Otherwise the
distortion of the muscle will make it difficult to
gauge the length of second incision. Figure
15.11C depicts the muscle lengthening after
completion of myotomy.
3. Closure of the conjunctiva is done as usual
for muscle surgery (Fig. 15.5J).
Fig. 15.11 Surgical technique of marginal myotomy.
FADEN OPERATION
Faden operation also known as posterior fixation
suture or retroequatorial myopexy is a
weakening procedure for the rectus muscles that
weakens the muscle only in its field of action by
decreasing the mechanical advantage of the
muscle acting on the globe.
Indications
This operation was first described by Cuppers
in Germany. The term Faden in German means
a suture or a sling. Indications of Faden
operation are as follows:
1. Dissociated vertical deviation. Suture is
placed in the superior rectus with or without
recession to treat vertical deviations.
2. Nystagmus blockage syndrome. Suture is
placed on the medial rectus with its recession
to treat the esotropia present in primary
position.
Principles of Non-Surgical and Surgical Management of Strabismus
449
3. Incomitant strabismus. In patients who are
orthotropic in primary position but have
diplopia in peripheral position of gaze sutures
are placed on the appropriate muscle for the
desired weakening effect.
4. Vertical strabismus present only in down
gaze. Sutures are placed on the inferior rectus
of the hypotropic eye.
5. Duane's retraction syndrome type I. The pro-
cedure is used to treat upshoot and downshoot
of the adducted eye.
6. Laterally incomitant exotropias may also be
managed by the Faden operation.
7. Non-accommodative type of convergences
excess esotropias are also reported to be
corrected by this procedure.
8. Near esotropias with high AC/A ratio which
is poorly controlled with hyperopic correction,
bifocals and miotics may be successfully treated
with bimedial recession combined with Faden
operation.
Surgical technique
1. Initial steps up to exposure of the muscle are
similar to those described for a usual recession
procedure.
2. Rotation of the globe. Application of posterior
fixation suture requires an excessive rotation of
the globe in opposite direction. This can be
accomplished by applying additional traction
suture at the insertion site (Fig. 15.12A).
3. Placing of posterior sutures. Faden operation
is performed with or without recession of
the muscle as per indication. When combined
with recession, first the muscle is disinserted
from the original insertion. The posterior
fixation sutures (5–0 Mersilene non-absorbable)
are placed through the superficial scleral
lamellae 12–15 mm behind the original insertion
(Fig. 15.12A). Then the recession procedure is
completed as usual and the posterior fixation
sutures are passed through the muscle and tied
(Fig. 15.12B).
4. Conjunctival closure is done in the usual
fashion (Fig. 15.5J).
Mechanics of the operation
When a posterior fixation suture is placed, the
effective insertion of the muscle is shifted
posteriorly. This decreases the muscle power in
its field of action without affecting the position
of the eyes in primary position. The weakening
of the muscle power in this procedure can be
understood as an artificial paresis resulting
from: (1) reduction of arc of contact R'
(Fig. 15.12C), (2) shortening of the active length
of the muscle (Fig. 15.12C), (3) the power of the
rectus muscle to rotate the eyeball depends upon
the leverage existing between the centre of
rotation c, C and the line of pull of the muscle at
tangential point T (Fig. 15.12D), after Faden
suture the moment arm M of the lever system is
decreased and more muscle force (3+) is now
required to rotate the globe by the same amount
(Fig. 15.12E), (4) probably some muscular
damage and decrease effectiveness of the
muscle contraction and, (5) a mechanical
restriction from reverse leash effect.
After this operation, the weakened (sutured)
muscle will require more innervation for a
particular movement. According to Hering's law
of equal innervation, the increased innervation
will also go to its yoke muscle. Thus indirectly
this operation also strengthens the yoke muscle
in the field of action (Fig. 15.12F and G).
For an appropriate effect von Noorden has
recommended the distance of posterior fixation
for different muscles as below:
Muscle Distance of Idieal
posterior insertion distances
Medial rectus 12–15 mm 14 mm
Lateral rectus 13–16 mm 16 mm
Superior rectus 11–16 mm 14 mm
Inferior rectus 11–12 mm 12 mm
Advantages of Faden operation
1. There is decreased likelihood of overadduction, especially in cases of non-accommodative convergence excess.
2. The upshoots and downshoots associated
with extreme adduction seen in Duane's
retraction syndrome are lessened.
3. Postoperative forced duction following this
procedure is free.
4. Last but not the least, it also saves the ciliary
blood vessels from damage associated with
recession/resection.
450 Theory and Practice of Squint and Orthoptics
Fig. 15.12 Surgical technique of Faden operation with recession of a rectus muscle (A and B) and mechanics of this
procedure (C to G). C, Normal arc of contact (R) and reduced arc of contact (R') after Faden operation. D, Normal length
of movement arm (M) of the rectus muscle lever system. E, Reduced length of movement arm (M') after Faden operation.
F, The innervation required (1+) to adduct the fixating nonparetic right eye is insufficient to abduct the left eye of a patient
with left lateral rectus palsy. G, A posterior fixation of the right medial rectus increases the innervational requirement (3+)
to adduct this eye. According to Hering's law of equal innervation, this increase innervation will also flow to the yoke muscle
in the fellow eye and thus will improve the abduction of the left paretic eye. [c: Centre of rotation; a: Normal anatomical
insertion; a': Anatomical insertion after Faden operation; T: Tangential point (physiological insertion); R: Normal arc of
contact; R': Reduced arc of contact after Faden operation; M: Normal length of movement arm; M': Reduced length of
movement arm after Faden operation].
Principles of Non-Surgical and Surgical Management of Strabismus
451
Problems associated with Faden operation
1. The procedure needs a vigorous traction of
the eyeball to facilitate suture application.
Even after this, it is difficult to apply sutures.
2. Vortex vein may be injured.
3. Chances of globe perforation are more.
4. Results are variable. A weakening effect of
0 to 10 prism dioptre in the field of action of
muscle is reported. Thus, either under
correction or over correction may occur.
INFERIOR OBLIQUE WEAKENING
PROCEDURES
Indications
1. Primary inferior oblique overaction. Bilateral
inferior oblique weakening is indicated for
bilateral overaction, even if asymmetrical.
2. Secondary overaction of inferior oblique
following superior oblique palsy. Unilateral
inferior oblique weakening is indicated.
3. Double elevator palsy. Inferior oblique muscle
weakening is indicated in the contralateral
eye.
4. Upshoots in Duane's retraction syndrome can
be controlled by the inferior oblique muscle
weakening.
Weakening procedures
1. Disinsertion, i.e. cutting the muscle from the
globe near its insertion.
2. Myectomy involves the excision of a segment
of muscle belly.
3. Extirpation refers to almost complete removal
of the muscle.
4. Recession involves disinsertion followed by
reattachment at the planned site.
5. Recession with anterior transposition
involves disinsertion and reattachment
near the lateral end of the inferior rectus
insertion.
The most commonly used procedures are
myectomy and recession. Some surgeons prefer
disinsertion and others recession with anterior
transposition. Each technique has its own
inherent advantages and disadvantages. And
each surgeon has his own reasons to prefer a
particular technique.
DISINSERTION
Surgical technique
Disinsertion alone is carried out through the
conjunctival incision placed at the inferior
border of the lateral rectus (Fig. 15.13A and B).
After conjunctival incision, the lateral rectus is
hooked first, then a second hook is passed to
engage the inferior oblique muscle near its
insertion (Fig. 15.13C). With traction between
the two hooks, good exposure is obtained and
the muscle is severed from the globe with
tenotomy scissors (Fig. 15.13C). The hook is
repassed so as to make sure that all fibres of the
inferior oblique have been successfully
disinserted from the sclera. It is also helpful to
make sure that the inferior oblique retracts into
the inferior orbital area and that it does not
reattach to the point from which it was severed.
Advantages
1. Procedure is very simple and easy.
2. There is no danger of placing sutures over
the macular area (of recession).
3. Bleeding is minimum (of myectomy).
Disadvantage
Incidence of recurrence of overaction is very
high.
INFERIOR OBLIQUE RECESSION
Surgical technique
1. Rotation of globe. Lids are separated with
universal eye speculum. A 5-0 Mersilene suture
is placed through the fused conjunctiva and
Tenon's capsule near the limbus in the inferotemporal quadrant and globe is elevated and
adducted by applying traction on this suture
(Fig. 15.13A).
2. Conjunctival incision. Either cul-de-sac
incision (Fig. 15.13A) or limbal incision is made
in the inferotemporal quadrant.
3. Exposure of muscle. With meticulous
dissection of the fascial connections, lateral
rectus and inferior rectus muscles are identified
and hooked away by the assistant. Anterior
border of the fleshly inferior oblique can then
be directly visualized (Fig. 15.13B). A muscle
hook is then passed between the sclera and
452 Theory and Practice of Squint and Orthoptics
Fig. 15.13 Surgical technique of inferior oblique disinsertion and recession (for explanation, see text).
Principles of Non-Surgical and Surgical Management of Strabismus
453
inferior oblique to engage the muscle. Inferior
oblique is dissected free of the intermuscular
septum and the fascia which joins it with the
lateral rectus (Fig. 15.13C).
4. Disinsertion of the muscle (Fig. 15.13D). After
the muscle insertion is exposed meticulously, it
is disinserted by tenotomy scissors and the
detached muscle is held by assistant with
serrated forceps.
5. Reinsertion of the muscle. Two 6-0 Vicryl
sutures are passed at its detached end and locked
by the whip suture technique (Fig. 15.13E). For
reinsertion of the muscle to various points on the
sclera depending the degree of weakness
required, following techniques are in vogue:
i. Park's technique. Park recommended that for
a 10 mm recession of the inferior oblique, the
medial needle should be passed through the
sclera at a point 2 mm lateral and 3 mm
posterior to the lateral aspect of insertion of
the inferior rectus muscle. The lateral needle
of the suture is placed more laterally
according to width of inferior oblique and
about 1 mm more inferiorly and the suture
are tied securely (Fig. 15.13F).
It has been reported that 10 mm Park's
recession is more effective in weakening
vertical functions of the muscle than 10 mm
Fink's recession (described below).
ii. Fink's technique. The classical Fink's technique
utilizes the lower end of lateral rectus muscle
as the landmark. For an 8 mm recession, the
muscle is inserted at a point 6 mm posterior
and 6 mm down to the inferior edge of the
lateral rectus muscle. A point 2 mm up or
2 mm down the above point gives a recession
of 6 mm and 10 mm, respectively.
iii. Elliot and Nankin's technique. This technique
provides anterior positioning of the inferior
oblique along with its recession. In this
technique, whole muscle is fixed just
temporal to the inferior rectus muscle
insertion.
6. Closure of the conjunctiva is done in the end.
Advantages
Presently, recession with or without anterior
positioning of the inferior oblique muscle is
preferred over disinsertion and myectomy
because of the following advantages:
• Recession can be graduated to produce
predictable results.
• It can be always revisited and the surgery can
be undone, underdone and overdone.
Disadvantages
Recession of inferior oblique is technically
difficult than the disinsertion and myectomy.
INFERIOR OBLIQUE MYECTOMY
Surgical technique
1. Initial steps up to exposure of the muscle are
similar to those for the recession (Fig. 15.14A
to C).
2. Myectomy. After meticulous exposures the
inferior oblique muscle is clamped with two
haemostats applied approximately 8 mm apart
(Fig. 15.14A) and the muscle segment in between
the haemostats is excised with tenotomy scissors
(Fig. 15.14B and C). It is important to observe
that all of the muscle fibres have been isolated
and cut. The stumps are cauterized to prevent:
– Postoperative haemorrhage,
– Reattachment of the muscle to the sclera, or
– Reattachment of the two stumps to each other.
3. Conjunctival closure is done as usual.
Advantages
• Technically easier to perform.
• Results are as good as recession.
Disadvantages
• Effect cannot be graduated.
• Myectomy is a destructive procedure and once
done cannot be controlled.
• Results may be unpredictable depending on
where the residual muscle stump reattaches.
SUPERIOR OBLIQUE WEAKENING PROCEDURES
Indications
1. Unilateral weakening of the superior oblique
is not commonly performed except as part of
the treatment of:
– Brown's syndrome, and
– Isolated inferior oblique muscle weakness.
454 Theory and Practice of Squint and Orthoptics
2. Bilateral weakening of superior oblique is
often performed with or without horizontal
muscle surgery for A-pattern deviations. This
surgery is expected to cause an eso-shift of up
to 30–40 prism dioptres in downgaze, little
change in primary position and almost no effect
in upgaze.
Weakening Procedures
1. Tenotomy, i.e. cutting of the tendon
2. Split lengthening of tendon
3. Recession
4. Silicon expander
5. Translational recession of Prieto-Diaz
6. Posterior tenotomy of superior oblique (PTSO)
SUPERIOR OBLIQUE TENOTOMY
Superior oblique tenotomy can be performed by
either nasal approach or a temporal approach.
Recently, most surgeons are preferring temporal
approach.
Fig. 15.14 Surgical technique of inferior oblique myectomy.
Surgical technique for temporal approach of
superior oblique tenotomy
1. Fixation of globe. Lids are separated with
universal eye speculum and a 5-0 Mersilene
suture is passed through the conjunctiva and
episcleral tissue near the limbus at approximately
11 o'clock position (right eye) or 1 o'clock
position (left eye). The eyeball is rotated
downward and inward by applying traction on
these sutures (Fig. 15.15A).
2. Conjunctival incision. An 8 mm cul-de-sac
incision is made in the superotemporal quadrant
starting just temporal to superior rectus insertion.
3. Exposure of the superior oblique tendon is carried
out taking following steps meticulously:
• After undermining the conjunctiva, the
intermuscular septum (between superior
rectus and lateral rectus) is buttonholed and
sclera is exposed.
• Superior rectus muscle is isolated, and engaged
in the muscle hook.
• Assistant further depresses and adducts the
eyeball by pulling on the superior rectus
muscle insertion with the help of muscle hook.
As this is done, the insertion of the superior
oblique is pulled down towards the incision.
Principles of Non-Surgical and Surgical Management of Strabismus
Fig. 15.15 Surgical technique of temporal approach for
superior oblique tenotomy.
455
• Thin and filmy glistening fibres of superior
oblique tendon are identified below the superior
rectus muscle after retracting it medially with
Desmarre's retractor. Then the superior oblique
tendon is engaged by a sweeping action of
the muscle hook. After the superior oblique
tendon is engaged, it takes substance and
appears thick.
4. Tenotomy. After the superior oblique tendon
is isolated on the muscle hook, a complete
transection of it is done with the help of
tenotomy scissors (Fig. 15.15C). It is recommended that in bilateral tenotomy, the
transection site on each tendon should be at
same distance from these insertion point to get
symmetric results. Such a measurement is
possible with the temporal approach but not
with the nasal approach.
Surgical technique for nasal approach of
superior oblique tenotomy
1. Conjunctival incision. The cul-de-sac incision
is made through the conjunctiva and Tenon's
capsule in the superonasal quadrant between
the medial and superior rectus muscles, about
4–5 mm behind the limbus. The wound is gently
spread with the help of tenotomy scissors
(Fig. 15.16A).
2. Exposure of the tendon. First of all the superior
rectus muscle is identified and engaged with a
muscle hook. The eyeball is rotated downward
and outward by applying traction on this muscle
hook. The upper edge of the wound is retracted
with a Desmarre's retractor and the glistening
white band of the superior oblique tendon is
identified (Fig. 15.16B).
3. Tenotomy. The superior oblique tendon is
engaged with a muscle hook and pulled forward
and is dissected meticulously from the
surrounding tissues. After the tendon is isolated
clearly, it is cut with the help of scissors
(Fig. 15.16C).
4. Conjunctiva is closed as usual.
• At this juncture, the conjunctival incision is
stretched temporally and also posteriorly with
the help of two separate muscle hooks or lid
retractors (Fig. 15.15B).
Superior oblique tenotomy, temporal versus
nasal appraoch
1. Nasal approach for performing superior oblique
tenotomy without striping the intermuscular