Transcript Complications following Strabismus surgery

Complications following
Strabismus surgery
F.Fazel :MD
Disease Entity
• Strabismus surgery is typically recommended
when a patient’s eye alignment can no longer
be treated with conservative measures such as
eyeglasses, eye patching, prisms, and
orthoptic exercises. Like many other
ophthalmic procedures, strabismus surgery
is very safe and effective, but complications
can occur and need to be diagnosed
and treated early to optimize
post-operative outcome.
Complications
• Unsatisfactory eye alignment is the most common
complication. Despite careful pre-operative
measurements and utilization of common surgical
dosage tables, a certain percentage of patients will be
overcorrected or undercorrected after.
Change in the refraction can occur, especially if two
muscles are operated in the same eye. For example,
operating on two horizontal muscles can induce a
small with-the-rule astigmatism This change is
temporary and resolves after a few months.
Complications
• Diplopia can occur, particularly in adult patients that are
overcorrected. Patients younger than age 10 typically can
suppress the deviated eye, but older patients may not
have suppression or, if suppression is present
pre-operatively, may not be able to shift the suppression
scotoma to cover an overcorrection.
• Scleral perforation can occur from an inadvertent deep
pass of the suture needle or during dissection to isolate
and disinsert the muscle tendon, particularly in the
presence of scarring during a re-operation. In most cases,
the perforation does not create a problem other
than a chorioretinal scar, but in some cases can
trigger endophthalmitis, vitreous hemorrhage,
or retinal detachment.
Scleral perforation
Scleral perforationn
Complications
• Post-operative infection can occur, usually within the first week
after surgery. Most infections occur around the initial surgical
incision into the conjunctiva. Suture abscess localized to knot
may occure. Rarely infections can penetrate deeper into the
orbit with proptosis, eyelid swelling, chemosis and erythema in
the classical presentation of orbital cellulitis,and sometimes
endophthalmitis can develop, either with or without a scleral
perforation.
• Allergic reactions can occur in response to either the suture
material or post-operative medications. Sometimes, these
reactions can be difficult to distinguish from post-operative
infections since they tend to occur in the same time frame.
Some patients present late with increasing inflammation
and discomfort; infection and allergic reaction should be
considered in this situation as well.
Posoperative infection
Endophthalmitis
Orbital cellulitis
Allergic reaction
Complications
Foreign body granuloma can develop,
usually a few weeks after surgery. The
granuloma typically presents at the suture site
as a localized, elevated, hyperemic mass
that is less than 1 cm in diameter
• Conjunctival inclusion cyst can present days
to years after surgery. This translucent
subconjunctival mass occurs when
conjunctival epithelial cells are buried
beneath the conjunctival surface
during surgery.
Pyogenic granuloma
Foreign body
Granuloma
Complications
Conjunctival scaring can be a persistent problem after
surgery. Instead of returning to the typical translucent
white appearance, the conjunctiva can remain
chronically hyperemic and pink, particularly after a
second or third operation. This complication can be
exacerbated by advancement of Tenon’s capsule too
close to the limbus, particularly during a resection, or by
advancement of the plica semilunaris onto the bulbar
conjunctiva. If severe, the conjunctival scarring itself can
cause a restrictive strabismus.
• Fat adherence can be cause by a violation of
Tenon’s capsule with prolapse of orbital fat.
The orbital fat can cause a fibro-fatty scar
that is adherent to the muscle and globe,
potentially leading to a restrictive strabismus.
Inclusion cyst
Conjunctival scar
Complications
Dellen can occur on either the cornea or sclera when thickened
bulbar conjunctiva (either from scarring, hemorrhage, or swelling)
prevents adequate and even lubrication of the ocular surface.
Fluorescein pools within the indentation of the cornea or sclera
without creating true staining.
• Anterior segment ischemia occurs when strabismus surgery
creates impaired blood flow to the anterior segment. Most of the
blood supply to the anterior segment flows through the ciliary
arteries within the four rectus muscles. Simultaneous surgery on
three rectus muscles in the same eye, or two rectus muscles in a
patient with compromised blood flow from vascular disease, can
cause ischemia. Typical findings in anterior segment ischemia
include iritis, corneal edema, folds in Descemet’s membrane and,
if severe, anterior segment necrosis and phthisis bulbi of the
operated eye.
• Eyelid retraction or ptosis can be caused by
strabismus surgery on the vertical rectus muscles.
The eyelid retractors, particularly in the lower eyelid,
are adherent to the intermuscular septum and fascial
tissue around the vertical rectus muscles. This connection
creates a shift in eyelid position during standard recession or
resection surgery of the vertical rectus muscles.
Dellen
Dellen
Anterior segment ischemia
Anterior segment ischemia
Lid retraction
Lid retraction
Complications
• Lost muscle occurs when the muscle slips
free of the sutures or surgical instruments
during surgery. This constitutes a surgical
emergency and immediate surgical attempts to
recover the muscle should be made.
• Slipped muscle occurs when the sutures
capture only the superficial muscular capsule
instead of securing the muscle belly.
Post-operatively, the muscle belly
retracts within the muscle capsule,
leading to clinical weakness of the
operated muscle.
Muscle slipage
Etiology
• Unsatisfactory eye alignment. It can also occur from preoperative measurement errors of the eye misalignment, intraoperative measurement errors in extraocular muscle position,
and excessive scarring or inflammation. Late causes of poor
alignment can come from poor sensory adaptation to the new
eye position.
• Change in the refraction post-operatively occurs from a change
in the force the extraocular muscle places on the cornea through
its attachment to the sclera. Over time, this change in force
usually reaches a new equilibrium, typically with restoration of
the original corneal refractive shape.
• Diplopia can occur in patients capable of vision in each
eye from an imperfect eye alignment. Small amounts of
residual vertical or torsional misalignments can be
difficult to fuse into a single image, particularly if
the misalignment is opposite to the pre-operative
misalignment (overcorrection). Rarely, patients
may have horror fusion,is, the inability to fuse
despite well-aligned eyes.
Etiology
• Scleral perforations can occur from an inadvertent deep pass
of the suture needle, particularly if the sclera is thinned from
a pathological change in eye structure, such as high myopia
with a staphyloma. It may also occur when the suture is placed
in the normally thinned sclera directly behind the muscle
insertion. Perforations can also occur during the dissection,
isolation, and disinsertion of the muscle tendon, particularly in
the presence of scarring that may make exposure and isolation
of the muscle tendon more challenging.
• Post-operative infections can occur if sterile technique is
violated or if the patient has a pre-existing condition
such as blepharitis or nasolacrimal stenosis that
increases the bacteria count at the surgical site.
• Allergic reactions occur sporadically in patients
that are sensitive to the materials or medications
used in the peri-operative period.
Etiology
• Foreign body granulomas occur sporadically in
susceptible patients. The exact etiology is unclear, since
the occurrence rate appears equal in primary and
secondary surgeries and the existence of a prior
granuloma does not appear predictive of subsequent
granulomas.
• Conjunctival inclusion cysts occur when conjunctival
epithelial cells are buried beneath the conjunctival
surface during surgery. These cells can multiply over
time to create a subconjunctival cyst days to years after
the original surgery.
• Conjunctival scaring is more common after a reoperation and also after a surgical resection, when
advancement of the muscle belly may advance the
thicker posterior Tenon’s capsule closer to the limbus
where it is more visible.
Etiology
Fat adherence is caused by violation of Tenon’s capsule
with prolapse of orbital fat. It is more common with
extensive posterior strabismus surgery
• Dellen is more common after a limbal incision than a fornix
incision, particularly in the presence of excessive scarring,
swelling, or hemorrhage. They are more common after
resection surgery than recession surgery. Any disruption of
the tear layer on the sclera or cornea can create a dellen.
• Anterior segment ischemia is more common in older
patients with microvascular risks factors such as diabetes
and hypertension. It also occurs more commonly in patients
with extensive prior peri-ocular surgery,such as scleral
buckling, that can diminish anterior segment blood flow.
Early recognition and treatment of ischemia with
corticosteroids is necessary to minimize the chance of
adverse consequences.
Etiology
• Eyelid retraction or ptosis can occur with any vertical rectus
rmuscle surgery, but is more prevalent with larger surgical dosages.
Lost muscle is common when operating on the medial rectus and
inferior rectus because of the shorter arc of contact. A lost muscle is
more common with tight or contracted muscles because the
increased passive tension increases the possibility of the muscle
tendon pulling free of sutures or clamps during surgery. A lost
muscle can occur in association with overall poor ystemic health.
Pulled In Two Syndrome (PITS) can happen when a weakened
muscle ruptures during surgery, typically at the junction
between the muscle belly and tendon,resulting in loss of the
posterior muscle belly.
• Slipped muscles occur when less than full-thickness
bites are used to capture the muscle tendon. Superficial
sutures only incarcerate the muscle capsule, allowing the
muscle belly to retract posteriorly when force is exerted during
contraction.
Risk Factors
Unsatisfactory eye alignment : patients with poor fusion
potential and in patients with more complicated types of
strabismus. Patients with dense amblyopia or structural problems
in one or both eyes have limited potential for binocular vision and
will not employ fusional mechanisms to improve or maintain eye
alignment. Similarly, patients with neuro-developmental
anomalies have been shown to have higher rates of
undercorrection and overcorrection after strabismus surgery.
Also, patients with more unusual and severe forms of
strabismus, such as 3rd nerve palsies, are more difficult to align
satisfactorily with surgery.
• Change in refraction:Operating on more than one muscle per
eye, particularly utilizing larger amounts of recession or
resection, can increase the risk of a change in refraction.
Diplopia is increased in adult patients who possess limited ability
to suppress the second image. The risk is also higher in more
complicated types of strabismus, particularly vertical, torsional, or
paretic forms of strabismus. In those patients, it may be more
difficult to create a useful area of single binocular vision.
Risk factors
Scleral perforations is increased if the sclera is thinned and also
if there is significant scarring or hemorrhage (more common
during a re-operation) that may impede exposure of the sclera for
suture placement. The risk is also greater with very posterior
suture placement, such as for posterior fixation sutures, because
it is more difficult to visualize and place the suture at the proper
depth in the sclera in the retroequatorial globe.
• Infection is increased if the patient has a pre-existing condition
such as blepharitis or nasolacrimal stenosis that increases the
bacteria count at the surgical site. It may also be increased in
very young patients, particularly those with developmental delay,
that may have difficulty cooperating with hygiene and antibiotic
eye drops after surgery.
• Allergic reactions is increased in patients with a history of
hypersensitivity reactions or systemic allergies or asthma.
• Foreign body granuloma appears to be related to the suture
material. With the elimination of gut sutures in most strabismus
surgeries, granulomas have become uncommon.
Risk factors
Conjunctival inclusion cyst is increased when the conjunctival
wound is not closed meticulously. In particular, for fornix
incisions, relying on simple apposition of the conjunctival wound
without sutures appears to increase the risk of subsequent cyst
formation.
• Conjunctival scarring is increased for a re-operation and also
after a surgical resection, when advancement of the muscle belly
may advance the thicker posterior Tenon’s capsule closer to the
limbus where it is more visible. Care must be taken to avoid
creation of conjunctival foreshortening or symblepharon.
• Fat adherence is increased with more posterior strabismus
surgery, such as operating on the inferior oblique muscle,
exploring posteriorly to retrieve a lost muscle, or dissecting more
posteriorly to place a posterior fixation suture.
• Dellen is higher for a limbal incision than a fornix incision,
because the subsequent irregularity of the perilimbal
• conjunctiva can cause a disruptin of the tear layer
• in the anterior sclera and cornea.
Risk factors
Anterior segment ischemia is higher when operating on multiple
muscles in the same eye, in older patients with microvascular
disease, and in patients with prior extensive eye surgery that
might also disrupt the ciliary vessels, such as scleral buckling
procedures.
• Eyelid retraction or ptosis is increased in subjects undergoing
vertical rectus recessions or resection with high surgical
dosages, particularly surgeries involving the inferior rectus.
• Lost muscle increases with poor overall systemic health, with
extensive scarring from prior eye surgery, and with surgery on a
tight, contracted muscle.
• Slipped muscle is increased when the muscle is tight, such as
with dysthyroid orbitopathy or the contracted antagonist of a
paretic muscle. A superficial suture pass is more likely
to capture just the muscle capsule, and the tight muscle is
more likely to retract within the muscle capsule after surgery.
Management
• Optical treatments include a change in
refraction, temporary or permanent prisms, or
optical blur or occlusion.
• Medical treatments include antibiotics –
topical, systemic, or intravitreal – and antiinflammatory medications, especially topical
corticosteroids.
• Surgical treatments include excisional
biopsies, release of scar tissue, treatment
of any retinovitreal disorders, and repeat
strabismus surgeries.
Optical therapy
• Optical therapy is directed at correcting any
change in refractive error following surgery.
Prisms may also be used in select cases to
alleviate diplopia
Medical therapy
Infections, topical antibiotics are used to treat conjunctivitis,
systemic antibiotics are used to treat preseptal and orbital cellulitis,
and intraviteal antibiotics are used to treat endophthalmitis
. Granulomas and conjunctival inclusion cysts, topical corticosteroids
are used for several weeks, with possible surgical excision if no
clinical response is observe.
Allergies, the antibiotic eye drops should be changed, with the
possible addition of a topical corticosteroid or antihistamine if the
symptoms persist.
Dellen formation, aggressive topical lubrication with artificial tears,
sometimes in conjunction with eye patching, can help until the
chemosis and swelling subside and the ocular surface becomes
smooth again.
Anterior segment ischemia, topical and systemic corticosteroids
can relieve inflammation until collateral vascularization can occur.
Surgery
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Lost muscle, an attempt should be made to retrieve the muscle promptly,
during the same surgery if possible. If the muscle cannot be retrieved,
a transposition surgery can be considered, although there is a risk of
anterior segment ischemia by performing surgery on three eye muscles
(the lost muscle plus two transposed muscles) at the same time.
Unsatisfactory post-operative alignment may or may not require surgical
correction. Sometimes prisms can be incorporated temporarily (fresnel
prisms) or permanently into eyeglasses and further surgery deferred. In other
situations, the prisms can be weaned slowly over time as fusional mechanisms
build, allowing single binocular vision without prisms. Many cases of
unsatisfactory eye alignment will need another strabismus surgery, particularly
in the case of a slipped muscle or restrictive scarring where the eye alignment
will not improve over time.
Scleral perforation may or may not require additional surgery.
Most cases resolve without treatment, but the presence of infection,
significant hemorrhage, or retinal detachment may require a
vitrectomy or other surgeries as indicated. The use of
cryotherapy or laser retinopexy at the time of perforation
is controversial in the absence of retinal perforation.
Surgery
• Foreign body granulomas and conjunctival inclusion cysts
may require excision if they are symptomatic and fail to respond t
o topical corticosteroids.
• Persistent conjunctival scarring or a dellen may require
surgery to remove scar tissue and smooth the conjunctival
surface.
• Eyelid retraction or ptosis may require oculoplastic surgery to
restore the normal lid configuration, particularly if the defect
prevents proper eyelid closure or affects peripheral vision.
• Lost muscle can benefit from pre-operative imaging to help
locate the muscle. Depending on the location,a posterior orbital
approach with the aid of an orbital surgeon can sometimes
successfully isolate and retrieve the lost muscle. If the attempt to
locate the muscle is unsuccessful, transposition surgery can be
effec at restoring primary gaze alignment.
Prognosis
• All of the complications of strabismus surgery, with
the notable exception of endophthalmitis, have an
excellent prognosis for recovery with proper
treatment. Many of the complications lessen or
disappear with time and conservative treatment,
while others respond well to additional surgery.
When severe, anterior segment ischemia can
progress to necrosis and phthisis bulbi, but most
cases resolve with corticosteroids over time.
Endophthalmitis, on the other hand, carries
a significant risk of permanent vision loss
even with prompt treatment.