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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5507_Библиотеки_им_академика_М_И_Перельмана.pdf
436 Theory and Practice of Squint and Orthoptics
Fig. 15.5 Surgical technique of medial rectus recession (for explanation, see text).
Principles of Non-Surgical and Surgical Management of Strabismus
437
3. Generally, perpendicular incision of about
4–5 mm long are made at both ends of the limbal
incision to facilitate exposure (Fig. 15.5C).
However, some surgeons prefer only one
perpendicular incision.
4. The limbal incision provides a direct access
to the Tenon's space. To separate the anterior
Tenon's capsule and intermuscular septum from
the sclera, the blades of a curved Steven's
tenotomy scissors are inserted into the upper
and lower quadrants and the blades are spread
gently only once (Fig. 15.5E).
5. A muscle hook is then inserted below the
muscle near its insertion and the muscle is
engaged by rotating the hook 180° (Fig. 15.5E).
6. The muscle is made prominent by applying
traction with the hook and lifting away the
conjunctival flap (Fig. 15.5H).
7. For a good exposure, the borders of the muscle
are then freed by sharp dissection of the facial
connections and the conjunctival surface of the
muscle in the anterior part is freed after severing
the check ligaments.
8. The muscle surgery is then performed as per
requirement (Fig. 15.5F to I) and after completion
of the procedure, the wound is closed by applying
sutures through the edges of the conjunctival flap
and the limbal tissue near the incision. Additional
sutures are applied to close the radial incision as
per requirement (Fig. 15.5J).
Advantages of limbal incision
• It provides a direct access to the Tenon's space
and thus a very little dissection of Tenon's
capsule is required to reach the muscle
insertion; this cuts down the bleeding and
scarring.
• With this incision, the normal anatomic
relations of Tenon's capsule and conjunctiva are
least disturbed and that it allows a fine closure.
• This technique is easy and quick and allows
optimal cosmetic and functional results.
• It is essential for a bare sclera closure (i.e. for
conjunctival recession).
• It is the most comfortable approach for
adjustable muscle surgery.
Note. Because of the above advantages, the limbal
incision has become technique of choice for
conjunctival recession, adjustable suture surgery,
repeat surgery and muscle transpositions.
Disadvantages
The disadvantages are a reasonably frequent
occurrence of dellen and retraction of the
conjunctival flap postoperatively but these are
minimal.
Over the muscle transconjuctival incision (Swan
approach)
Technique
In this approach, an incision in both, the
conjunctiva and Tenon's capsule is made over the
muscle. For the medial rectus, the incision is
placed 1–2 mm anterior to the plica semilunaris
and for the lateral rectus, the incision is made
midway between the limbus and the lateral
fornix. The sub-Tenon's space is freed by
spreading the scissors points. The muscle is
engaged by the muscle hook and is freed from
facial connections by sharp dissection.
Advantages
The only advantage of this approach is that
limbal area is not disturbed and so there are no
chances of formation of cosmetically unsatisfactory ridge at the limbus and thus no problem
of dellen formation.
Disadvantages
This incision has been reported to produce
fibrosis over the muscle resulting sometimes in
a cosmetically unacceptable conjunctival scar
and also making the resurgery (when required)
more difficult. So, most of the squint surgeons
are not preferring this approach.
Cul-de-sac (fornix) incision (Park's approach)
Technique
1. In this approach, a combined conjunctival and
Tenon's capsule incision is made in the bulbar
conjunctiva just near the cul-de-sac (1–2 mm to
the limbal side of cul-de-sac). This incision is
parallel to the fornix, approximately 8 mm in
length and depending upon the muscle to be
operated at following sites:
• For surgery on medial rectus, assistant is asked
to grasp the limbus in the inferior nasal
quadrant and rotate the eyeball upward and
438 Theory and Practice of Squint and Orthoptics
outward; and an incision is made in the inferonasal quadrant which terminates just
temporal to the semilunar fold.
• For surgery on the lateral rectus, the assistant
should hold the limbus in the inferotemporal
quadrant and rotate the eyeball up and in, and
the incision made in the inferotemporal
quadrant should extend temporally from an
imaginary line dropped into the cul-de-sac
that divides the lateral and middle third of
the cornea.
• For inferior rectus surgery, incision is made in
the inferior cul-de-sac with its centre at
6 o'clock position.
• For superior rectus surgery, incision is made in
the superior cul-de-sac with its centre at
12 o'clock position.
• For surgery on inferior oblique muscle, incision
is made in the inferotemporal quadrant
(inferior cul-de-sac).
• For surgery on the superior oblique muscle, an
incision is made in superior cul-de-sac,
situated just temporal to the superior rectus
muscle.
2. The Tenon's capsule and intermuscular septa
are cut down to bare sclera.
3. The muscle concerned is hooked from the bare
sclera exposed, freed from the various fascial
connections and the muscle surgery is
performed as per requirement.
4. In the end of surgery, the conjunctiva is
reposited back into the fonix by a gentle
massage. Usually, no suture is required to close
unless an exposed, gaping wound is visible
between the palpebral fissure.
Advantages
• Provides a wider field of view and better
access to the extraocular muscles and so is
suitable for more complex surgeries requiring
extensive muscle work.
• Often no sutures are required for closure.
• There are no visible conjunctival or Tenon's
scars.
• This approach is useful not only for horizontal
rectus surgery but also for procedures on the
vertical recti and obliques.
Disadvantages
• Technique is bit difficult as compared to the
limbal approach.
• The exposure is depended upon the technique
of assistance.
• May lead to more postoperative discomfort
due to a larger incision.
• Slightly increased risk of infection compared
to smaller incisions.
Closure of the conjunctival incision
Following the completion of extraocular muscle
surgery, the conjunctival wound should be
closed by any of the following techniques
depending upon the type of incision given:
1. Closure of limbal incision is accomplished by
interrupted sutures (Fig. 15.5J).
2. Closure of over the muscle conjunctival incision
can be carried out either with running sutures
or with the interrupted sutures.
3. Swan closure technique comprises suturing of
Tenon's capsule and conjunctiva independently
in two layers. Usually Tenon's capsule is closed
with vertical placed 6-0 Vicryl sutures and
conjunctiva is closed with horizontally placed
6-0 silk sutures.
4. Horizontal closure following a vertical incision by
interrupted or running suture is preferred by a
few surgeons.
5. Bare sclera closure technique is indicated in cases
in which previous surgery or injury has led to
severe fibrosis of the conjunctiva and episcleral
tissues, producing a mechanical limitation of
motion. Making of the limbal incision is
mandatory, when bare sclera closure technique
is planned. In this technique, the conjunctiva is
attached directly to the sclera by interrupted
sutures, leaving a bare scleral area between the
conjunctival margin and the limbus. The area
heals by the gradual proliferation of conjunctival
epithelium.
Note. It is important to emphasize that the
conjunctiva and its closure play an important
role in the surgical results. It is mandatory that,
following the closure of the conjunctiva, forced
ductions be carried out to make sure that the
conjunctival closure does not provide any
mechanical limitation.
Principles of Non-Surgical and Surgical Management of Strabismus
439
RECESSION OF RECTUS MUSCLES
RECESSION OF MEDIAL RECTUS
After the muscle has been exposed by any of
the above described techniques (most surgeons
are preferring von Noorden's limbal approach),
the salient points of the technique of medial
rectus recession are as follows:
1. Exposure of the muscle (Fig. 15.5A to E). It is
especially important on the medial rectus to free
the check ligament, since failure to do so may
result in retraction of the caruncle postoperatively. It is also important to ensure
whether the muscle is completely engaged or
not. It is done by passing a second muscle hook
repeatedly under the insertion from above or
from below.
2. Passing of sutures through muscle (Fig. 15.5F).
After the muscle has been meticulously
separated, the position of the insertion is noted
and two single armed sutures (6-0 Vicryl with
spatulated needle) are placed and locked (by
whip suture technique) at both margins of the
muscle close to the insertion. After the locking
stiches, the suture ends are tagged with bulldog
clamps for identification.
3. Cutting the muscle (Fig. 15.5G). Traction to
the muscle hook and sutures is applied and the
muscle is cut free of the insertion from the sclera
using curved Stevens tenotomy-scissors.
Bleeding from the cut insertion site is controlled
by applying pressure or using wet field cautery.
4. Securing of muscle at the new insertion site
on the sclera (Fig. 15.5H). Eyeball is stabilized by
grasping the stump of the insertion remaining
on the sclera with a forceps and the new insertion
(depending upon the predetermined amount of
recession) is measured and marked with the help
of a caliper. The needles are then passed through
the sclera parallel to the limbus at the previously
marked distance. It is important to note that
needle should be visible at all times while passing
through the scleral lamellae, so as to avoid
perforation. The muscle is then secured to sclera
by tying the sutures (Fig. 15.5I). It is important
that the knots be tied securely and to the sclera
directly, rather than on top of the muscle.
Preferably the muscle should be spread out to its
normal width. Following the completion of the
reattachment of the muscle, the amount of
recession actually carried out should again be
measured with the help of caliper.
5. Closure of the conjunctival incision should
be done depending upon the type of incision
used (see page 436, Fig. 15.5J).
Limits of medial rectus recession
• Maximal limits. Most of the previous reports
and conservative surgeons recommend that
with a normally acting lateral rectus muscle,
the medial rectus muscle should not be
recessed more than 5.5 mm. In the presence
of a paralytic lateral rectus, the medial rectus
can be recessed up to 6.5 mm. However, recent
reports suggest that MR can be recessed up to
7–8 mm without producing significant
limitation of adduction postoperatively.
• Minimal limits. It has been recommended that
minimal limit for MR recession is 3 mm,
because recession of MR less than 3 mm has
hardly any effect.
RECESSION OF LATERAL RECTUS
• The technique of recession of lateral rectus is
essentially the same as that of medial rectus
recession.
• It is important to remember that owing to close
proximity of the inferior oblique insertion to the
inferior border of lateral rectus muscle, the
former is commonly hooked and sometimes
even along with the latter dissected and inserted.
Therefore, an extra care is required to prevent
this complication. It is recommended that
preferably lateral rectus should be engaged/
hooked from the superior border side.
Limits of lateral rectus recession
• Maximal limits. Under normal circumstances,
lateral rectus should not be recessed more
than 8–10 mm. However, in patients with a
large degree exotropia in blind eye, the
amount of LR recession may be more, but in
such cases usually there is slight limitation of
abduction postoperatively.
• Minimal limits. Minimal amount of lateral rectus
recession recommended is 5 mm, since LR
recession less than this has little effect per se.
440 Theory and Practice of Squint and Orthoptics
RECESSION OF SUPERIOR RECTUS
• The technique of recession of superior rectus
is essentially the same as that described for
medial rectus.
• It is important to remember that accidently
superior oblique tendon may be hooked while
engaging the superior rectus muscle. Care
should be taken to avoid it.
RECESSION OF INFERIOR RECTUS
• Essentially, the technique is similar to
recession of any other rectus muscle.
However, one should dissect carefully the
intermuscular septum and all fascial
connections between the inferior rectus
muscle and Lockwood's ligament as far
posteriorly as possible.
• While dissecting the fascial connections of
inferior rectus muscle, one should take care
to avoid injury to the nerve to inferior oblique
muscle, which enters this muscle just as it
passes the lateral border of the inferior rectus
muscle, 12 mm posterior to the inferior rectus
insertion.
HANG-BACK TECHNIQUE OF RECTUS MUSCLE
RECESSION
Hang-back (HB) technique of rectus muscle
recession is a type of non-adjustable suspension
recession (SR) technique. It is reported to be
equally effective and comparatively safer than
the conventional recession technique. It is
performed for up to 7 mm of recessions.
Surgical steps
1. Initial steps up to isolation of the muscle are
similar to conventional recession (see page 439
and Fig. 15.5A to E).
2. Passing of suture through the muscle. A double
armed 6-0 Vicryl suture is passed through the
muscle 1.0 to 1.5 mm from the insertion. Locked
bites are taken at each end of the muscle (Fig. 15.6A).
3. Disinsertion of the muscle is then carried out
with the help of tenotomy scissors.
4. Placing of sutures on the sclera for hang-back
recession as described by Potter and Nelson are
as follows:
• The suture needles are passed through angled,
5 mm scleral tunnels that are 6 mm apart from
each other and begin where the posterior side
of the insertion merges with flat scleral fibres
and emerge anterior to the insertion as close
to each other as possible (Fig. 15.6.B).
• The sutures are then pulled forward until the
cut end of the muscle rests firmly against the
posterior aspect of the insertion (Fig. 15.6C).
• The calipers are opened equal to the amount
of recession and aligned perpendicular to the
suture arms. In this position, then the sutures
are clamped with a locking needle holder
placed just inside the proximal caliper tip
(Fig. 15.6C). The surgeon must observe metalto-metal (caliper tip to needle holder tip)
contact during this step to prevent asymmetric
suture lengths and unequal recession of the
ends of the muscle. Four overhand knots are
tied and trimmed while the needle holder
clamps the sutures firmly.
• The needle holder is then removed and the
muscle retracts until the knot rests against the
insertion (Fig. 15.6D). The eye is rotated in the
opposite direction with the toothed forceps to
facilitate the posterior movement of the muscle.
• Finally, the caliper is placed from the insertion
to the anterior end edge of the muscle to verify
its position (Fig. 15.6D).
5. Conjunctival closure is carried out with 6-0
Vicryl sutures as usual (Fig. 15.5J).
HEMIHANG-BACK TECHNIQUE OF RECTUS
MUSCLE RECESSION
Hemihang-back (HHB) technique of rectus
muscle recession is a type of non-adjustable
suspension recession (SR) in which the muscle
is reattached and suspended from the sclera
posterior to the original insertion. It is performed
for more than 7 mm of recession.
Surgical technique
1. Initial steps up to disinsertion of the muscle are
similar to hang-back technique.
2. Placing of sutures on the sclera in hemihang-back
technique (Potter and Nelson).
• The calipers are first set on one-half of the total
proposed amount of recession (e.g. for 10 mm
recession, initial caliper setting should be
5 mm). As in a conventional recession, the
calipers are used to mark the entrance points
Principles of Non-Surgical and Surgical Management of Strabismus
for the scleral tunnels posterior to the
insertion. The entry points are marked 6 mm
apart (Fig. 15.7A).
• The sutures needles are then passed from the
entry point through angled, 3 mm scleral
tunnels that emerge next to one another
(Fig. 15.7A).
• Further steps to produce another 5 mm of
suspension recession are similar to hang-back
technique (Fig. 15.7B).
• In the end, the calipers are reset for total
amount of recession (10 mm or above) and the
total recession from the original insertion is
verified (Fig. 15.7C).
3. Conjunctival closure is performed as usual.
Advantages of hang-back and hemihang-back
techniques
1. The risk of scleral perforation is reduced in
both procedures because the surgeon works
from a comparatively more anterior site than
would be selected in a conventional recession.
2. Advantage of HHB is that it minimizes
awkward needle placement in the sclera.
3. These techniques avoid excessive manipulation
of the eye which may lead to decreased
postoperative inflammation and more effective
muscle weakening.
4. Post-equatorial exposure which risks injury
to the vortex veins is not required in these
techniques.
5. Chances of postoperative, induced cyclo-
vertical deviations, are less with suspension
recession techniques.
441
Fig. 15.6 Hang-back technique of rectus muscle recession
(for explanation, see text).
RESECTION OF RECTUS MUSCLES
RESECTION OF MEDIAL RECTUS
Steps of the resection of the medial rectus muscle
are as follows:
1. Conjunctival incision is similar to recession
technique (see page 435).
2. Exposure of muscle. Basic technique is same
as described for recession procedure (see page 439).
However, while exposing the muscle for
resection, the muscle should be freed only up
442 Theory and Practice of Squint and Orthoptics
Fig. 15.7 Hemihang-back technique of rectus muscle recession (for explanation, see text).
to requirement for resection, keeping the fascial
attachments intact as much as possible (c.f.
recession).
3. Passing of sutures through the muscle. After
the muscle has been meticulously separated, it
is slightly stretched using two muscle hooks–
one just under the insertion and another about
10 mm away from it. The amount of muscle to
be resected is measured and marked with the
caliper (Fig. 15.8A). Two double armed 6-0
Vicryl sutures are passed at the marked site and
are locked using the whip suture technique
(Fig. 15.8B). A Jamson resection clamp or any
fine hemostat is applied just anterior to the
suture (Fig. 15.8C).
4. Cutting of the muscle. The muscle hook near
the insertion is stretched and the muscle is
disinserted using Westcott or Stevens tenotomy
scissors (Fig. 15.8D). Then the muscle tissue
anterior to the clamp/hemostat is excised with
the help of tenotomy scissors (Fig. 15.8E) (some
surgeons do not apply any clamp and cut the
muscle tissue 1 mm anterior to the sutures after
crushing with a hemostat).
5. Securing of muscle to the insertion site
(technique-I). After the requisite amount of
muscle has been resected, the four needles of
the two double-armed sutures are passed
through the superficial scleral lamellae just
below the original insertion stump in a vertical
fashion; one needle of each suture being
placed close to the centre of the insertion site
and the other through the corresponding end
(Fig. 15.8F). After pulling the cut muscle end up
to the old insertion, each suture is tied with a
tripple knot (Fig. 15.8G).
Alternative technique of securing the muscle
(technique-II). Some surgeons, after marking the
resection site, apply the muscle clamp just
anterior to it (Fig. 15.9A) and then disinsert the
muscle (Fig. 15.9B and C) followed by placing
2-double-armed sutures through the insertion
site (Fig. 15.9D). The sutures are then carried
through the muscle which is lifted by clamp
(Fig. 15.9D). The assistant then pulls the muscle
with the clamp towards the old insertion site
and the surgeon ties each suture with a triple
knot (Fig. 15.9E). The muscle is then crushed just
anterior to the sutures with the help of a
haemostat (Fig. 15.9F) and then cut using
tenotomy scissors (Fig. 15.9G).
6. Spring-back balance test of Jampolsky should
preferably be carried out after the completion
of resection to prevent overcorrection. To
perform this test, eyeball is grasped at the limbus
with two fixation forceps (similar to forced
duction test) and is rocked back and forth
several times in the desired plane and then
quickly released noting the velocity of spring
back and final position of the eyeball. Following
observations may be made:
• If, for example, medial rectus has been over
corrected, the eye ball will come to rest in a
position of adduction. Under such circumstances, the surgeon should recess the just
resected muscle to avoid overcorrection.
Principles of Non-Surgical and Surgical Management of Strabismus
443
Fig. 15.8 Surgical technique I of medial rectus resection (for explanation, see text).
444 Theory and Practice of Squint and Orthoptics
Fig. 15.9 Surgical technique II of medial rectus resection (for explanation, see text).
Principles of Non-Surgical and Surgical Management of Strabismus
445
• If the position of the eyeball after the spring-
back balance test suggests the need for
additional strengthening, then the resected
muscle should be advanced 2 mm towards the
limbus.
7. Closure of the conjunctiva is performed as
usual (Fig. 15.5J).
RESECTION OF OTHER RECTUS MUSCLES
• The technique of resecting other rectus
muscles is essentially the same as described
for the medial rectus.
• Special points to be taken care for during each
rectus muscle are same as described for the
recession technique.
Limits of rectus muscle resection in mm
Maximal Minimal
Medial rectus 8–10 4
Lateral rectus 12–14 4– 5
Superior rectus 5–6 2–3
Inferior Rectus 5–6 2–3
ADJUSTABLE SUTURES IN
RECTUS MUSCLE SURGERY
Keeping in view the unpredictable results of
strabismus surgery, the adjustable suture
technique which permits alteration in the results
in the immediate postoperative period, is
becoming popular.
Indications
Should adjustable suture surgery be performed
in every case of strabismus is controversial; no
convincing data are available to show that longterm results with this technique are superior to
conventional methods. However, adjustable
surgery is useful in conditions where the results
of strabismus surgery are comparatively less
predictable, as below:
• Patients with long-standing deviation.
• Acquired strabismus with fusional potential.
• Patients with paralytic squint requiring large
recession and resection.
• Patients with restrictive strabismus in which
accurate assessment of muscle function is
difficult.
• Re-operation.
• Strabismus due to long-standing aphakia with
good visual acuity, bothered by diplopia.
• All cases of strabismus where diplopia is the
prime problem and thus needs precise
postoperative results.
Prerequisites
Adjustment suture surgery needs an alert and
attentive patient who will co-operate for
measurement of the deviation in required
position. In general, adjustable suture surgery
can be undertaken in adults and children above
11–12 years of age who will be able to co-operate
for the procedure.
Technique
Various adjustable strabismus surgery techniques
include, 'pull over (stay) sutures', 'topical
anaesthesia' or 'awake strabismus surgery', postoperative adjustable (two stage) surgery and
'operation/reoperation technique'. Out of these,
'postoperative adjustable (two-stage) suture
technique' is most popular. Therefore, only this
technique will be discussed here.
Steps of postoperative adjustable suture
technique with recession
1. Initial surgical steps up to meticulous exposure
of the muscle are same as in usual recession
procedure (see page 435–439).
2. Passing of suture in the muscle. A double-armed
6-0 Vicryl suture is passed and tied through the
centre of tendon and then passed and locked
through its upper and lower edges, near the
insertion (Fig. 15.10A).
3. Cutting of the muscle. The muscle is severed
near its insertion with tenotomy scissors.
4. Placing of sutures in the sclera. In this technique,
instead of placing sutures in the sclera at a
measured distance away from the original
insertion (as done in usual recession), the sutures
are passed directly through the insertional
stump. To facilitate postoperative suture
adjustment, the scleral tunnel created by the
suture is widened by moving the sutures back
and forth several times. The muscle is allowed
to recede a desired amount of recession,
measured by caliper (Fig. 15.10B), and the
sutures are tied first with a single knot, and then
with a bow knot (Fig.15.10C). The end of the
suture that will open the knot is cut long for later
identification.