squint surgeries
TRANSCRIPT
Squint SurgeriesDr. Gauree Krishnan
DNB 2nd yearAhalia Foundation Eye Hospital
Indications
• Nearly equal VA post orthoptic Rx, BSV improved
To correct squint cosmetically as well as functionally
• Untreatable deep amblyopia in one eye, persistent ARC, absence of power of fusion
• Sensory squint sec to organic disorders
To correct squint only cosmetically
• Assumed to relieve diplopia (SO or LR palsy) or improve vision (nystagmus or eccentric null point)
To correct abnormal head posture
• Hypertrophied conjunctiva or Tenon’s capsule from prior muscle surgery
To relieve mechanical restriction or to improve appearance
Optimal time for squint surgery
• Depends on– Type of squint– Age of the patient– Various sensory adaptations
In children too young for orthoptic treatment (<4 to 5 yrs)
a) Constant squint-
b) Intermittent squint –Observed and
refracted every six months
Orthoptic treatments
tried
Last option surgery
Concomitant Squint
present after wearing glasses for
a month
alternating, almost equal
vision operate asap
if visual axes are put within few degrees of
parallelism
BSV may develop
In children old enough for orthoptic treatment (>4 to 5 yrs)a) Initially all optical & orthoptic treatments tried
to treat the associated sensory adaptation (supression , amblyopia, ARC)
b) In the presence of ARC early surgery good cosmetic & functional results
c) In the absence of true fusion early surgery for cosmetic reasons fusion may develop
In older children (>12yrs) and adultsCan be decided at leisure as only cosmetic prognosis
Paralytic Squint
• Timing : – Not too early (as may resolve spontaneously)– Not too late ( may keep detoriating)– Ideally after 3 to 6 months
COMMON SURGICAL TECHNIQUES
Muscle Weakening Procedures
•most common•changes the arc of contact with the globeRecession
of EOM •weakens muscle by educing the no. of contractile fibres•Effective post recession•Indicated where recession is c/I as in scleral buckled
globe, thin scleraMarginal myotomy
•Seldom done•Inferior oblique
Myectomy
Muscle Weakening Procedures
•Disinsertion of rectus muscleFree tenotomy
•Posterior fixation sutures•Retropexy of an EOM•Doesn’t affect deviation in primary position •Weakens the muscle action in patients who are already
orthtropic
Faden’s operation
Muscle Weakening Procedures
•May help in augmenting the weakening effect of rectus muscle
•For large deviations•Specially after previous surgeries
Recession of conjunctiva and tenon’s capsule
•Controlled weakening procedure for superior obliqueMuscle lengthening by insertion of a
silicone expander or a non
absorbable suture material
Muscle Strengthening Procedures
•Most common•strengthens by shortening the length of muscle•Excessive should be avoided , since this may
restrict eye movements in opposite direction
Resection•Not a primary procedure•Can be done on resected muscles•Or in over- recessed muscle
Advancement
•Not preferred for recti•Superior Oblique when tucked, improves
depression in adducted eye and
Tucking
Procedures that change direction of muscle action
•For A- or V- pattern without associated oblique muscle dysfunctionVertical transpositioning of
horizontal recti
•For correction of A- or V- patternHorizontal transpositioning of
the vertical recti
•For correction of A- or V- patternSlanting of the rectus muscle insertion
•Hummelshein, Knapp, JensenTransplantation of muscles in paralytic
squint
General Considerations
•Surgery should be delayed till after all possible amblyopic exercises•If still untreatable , surgery should be preferred in the worse eye
Amblyopia
•While planning surgery for horizontal strabismusVertical Incomitancy
•In case of unequal deviations in right and left gazesHorizontal Incomitancy
•Prefer unoperated muscle•In presence of excessive restriction, reoperation on the involved
muscle gives better results•In multiple surgeries, at least one rectus muscle should be unoperated
in each eye
Previous surgery
•Esodeviation- basic, con ex, div ins•Exodeviations- basic, con ins, div exDistance and near
measurements and AC/A ratio
•Succinylcholine (GA) may cause sustained contraction of EOM for 20 mins, so use non depolarizing drug
FDT
GuidelinesSurgeon factor
Degree of squint – same amount of muscle surgery may give different results in smaller or larger deviation
Age of patient and duration of squint
Effect of Recession > resection
Intractable amblyopia
Effect of MR > LR
Effect of vt> hz recession
Combined recess resect> individual muscle
Anaesthesia
Topical
• Cooperative patients only
• Only for simple recession surgeries
• Allows readjustment of muscle position during surgery to effect cosmetic or functional results
Local
• Surface + nerve / peribulbar block
General
• c/I succinylcholine false FDT
• Risk of oculocardiac reflex, oculodepressor reflex, oculorespiratory reflex
• Relative position of eye may changeleading to undercorrection
SURGICAL STEPS
Fixation of globe
• For Hz rectus – 6 or 12 o’ clock• For Vt rectus – 9 or 3 o’ clock• For IO muscle- 4 ½ o’ clock in left eye
• 7 ½ o’ clock in right eye• After fixing eyeball is rotated away from the
muscle being operated
Conjunctival incision and exposure of the globe
Limbal incision or von Noorden’s approach
• Adv:• very little dissection
of Tenon’s capsule required
• Maintains normal anatomic relations
• Easy and quick• Disadvan:
• Dellen• Retraction of
conjunctival flap
Over the muscle (Swan approach)
• Adv:• No limbal
disturbance• No dellen formation
• Disadv:• Fibrosis• scarring
Cul-de-sac (fornix) incision ( Park’s
aaproach)
• Adv:• No suture required• No visible scars• Can be used for hz ,
vt, obliques• Disadv:
• Difficult
Complete exposure of muscle
Passing of sutures through muscle Cutting the muscle
Securing of muscle at the new
insertion site on the sclera
Closure of conjunctival
incision
Recession of medial rectus
Limits: 3mm to 7-8 mm
Recession of lateral rectus
• LR should be preferably hooked from the superior border side
• Close proximity of the inferior oblique insertion to the inferior border LR
• Limits: 5mm to 8-10 mm
Recession of superior rectus
• Care should be taken to avoid accidental hooking of superior oblique muscle
Recession of inferior rectus
• Careful dissection of intermuscular septum and all fascial connections between IR and Lockwood’s ligament as far posteriorly as possible
• Avoid injury to nerve to inferior oblique, which enters the muscle just as it passes lateral border of IR muscle
Hang back recession of rectus muscle
• Type of non adjustable suspension recession technique
• Performed for up to 7 mm of recessions• Comparatively safer and equally effective
Hang back recession of rectus muscle
Hang back recession of rectus muscle
Isolation of muscles Passing of suture through the muscle Disinsertion of muscle
Placing of sutures on the sclera for hang
back(Potter and Nelson)
Conjunctival closure
Hemi Hang back recession of rectus muscle
Advantages of hangback and hemi hangback
Less risk of perforation since more anterior site than conventional recession
HHB minimizes awkward needle placement in the sclera
Technique avoids excessive manipulation of eye
No risk to vortex veins as no post equatorial exposure
Less risk of post surgical induced cyclovertical deviations
Resection of medial rectus
Conjunctival incision
Exposure of muscle (Only uptil
req resection)
Passing of sutures through the
muscle
Cutting of the muscle/ crushing
with hemostat
Securing of muscle to the
insertion site – 2 techniques
Spring back balance test of
Jampolsky
If undercorrected advancement of
MR
If overcorrected recession of MR
Closure of conjunctiva
Limits of rectus muscle resectionRectus Maximal (mm) Minimal (mm)
Medial 8-10 4
Lateral 12- 14 4- 5
Superior 5- 6 2- 3
Inferior 5- 6 2- 3
Marginal Myotomy
Faden’s Operation
Exposure of muscle
Rotation of globe in opposite sirection
Placing of posterior fixation sutures
Conjunctival closure
Indications of Faden’s operation• To correct DVD• Patients having incomitant strabismus with orthotropia in
primary position• To treat upshoot and downshoot of the adducted eye in
patients with Duanne’s retraction syndrome Type 1• Near Esotropia with high AC/A ratio• Persistent eso after max recession and resection surgery• To dampen nystagmus in• Nystagmus blockage syndrome
Efficacy {MR > Vertical recti > LR}
Faden’s Operation
Advantages• Decreased chances of over
adduction ( sp in non accommodative convergence excess)
• Post-op FDT is free• Saves the ciliary vessels
from damage
Disadvantages• Needs vigorous traction for
suture application• Vortex vein injury• Higher globe perforation
chances• Variable results
Inferior Oblique weakening procedures
Indications• Primary IO overaction• Secondary overaction of IO
following SO palsy• Double elevator palsy – IO
weakening indicated in the other eye
• Upshoots in Duanne’s retraction syndrome
Types of procedures• Disinsertion• Myectomy- excision of a segment
of muscle belly• Extirpation- almost complete
removal of muscle• Recession
– Park– Fink– Elliot and Nankin
• Recession with anterior transposition- disinsertion and reinsertion near the IR insertion
Superior Oblique weakening procedure
Indications• Unilateral weakening:
– Brown’s Syndrome– Isolated IO muscle weakness
• Bilateral weakening :– With/ without hz muscle
surgeryfor A- pattern deviations
– Causes eso shift of 30-40 prism dioptres in downgaze, little change in primary position and almost no effect in upgaze
Procedures• Tenotomy• Split lengthening of tendon• Recession• Translational recession of
Prieto-Diaz• Posterior tenectomy of SO
Superior Oblique Tenotomy
Translational recession of Prieto-Diaz
Posterior tenectomy of SO
Superior Oblique strengthening procedure
Harada Ito procedure
Superior Oblique Tuck
Harada Ito procedureSelective strengthening of the anterior fibres of SO muscle
Considered responsible for torsional action of SO
Anterior and lateral displacement of the anterior fibres
enhances incyclotropic action
corrects excyclotropia
Harada Ito procedure
Superior Oblique Tuck
• Indications:– SO paresis– DVD
• Note:– A transient post op
pseudo Brown Syndrome due to limitation of elevation of adducted eye
Muscle Transposition Procedures
• Moving the EOM out of their original planes of action
• Generally for paralytic strabismus• Indications:– III, VI and double elevator palsies– A- , V- patterns – Cyclodeviations– Small hz and vt deviations
Knapp procedure
Transposition of LR and MR To IR or SR
Jensen’s Procedure
Transposition of half thickness of
SR and IR
To Lateral Rectus
Hummelsheim procedure
Total transplant
of SR and IR
To Lateral Rectus
COMPLICATIONS
Complications of anaesthesia
• Cardiac arrest• Malignant hyperthermia• Hepatic porphyria and suxamethonium
sensitivity• Oculorespiratory reflexes• Succinyl choline induced apnea
Intraoperative complications
• Mild – conjunctival• Moderate- muscle• Profuse- vortex veins
Haemorhage
• Most frequent- MR• Intraop or post op
Lost muscle
• During disinsertion of muscle• During placement of needles for reinsertionof the muscle
Perforation of globe
• Excessively rotated globe• During re operation , modified anatomy• Myectomy of IR during myectomy of IO
Operation of wrong muscle
• Disinsertion of IO during LR surgery• Complete severance of SO tendon or sheath while attempting to
hook SR
Inadvertent injury to other muscles
Operation in the wrong eye
Post operative complications
1) Infections– Endophthalmitisorbital cellulitis– Localized suture abcess
2) Suture reaction3) Conjunctival granuloma4) Conjunctival cyst– Due to inadvertent closure of conjunctiva in the
wound
5) Anterior segment ischaemia• Cause
– Disruption of blood supply to the anterior segment from anterior ciliary arteries• Signs
– Corneal oedema– Stromal swelling– DM folds– Heavy AC reaction– Cataractous lens
• Prevention– All 4 recti should never be disinserted simultaneously– Period of 6 months bewteen hz and vt muscle surgeries– Muscle slpitting procedures– Modified tucking procedures
Post operative complications
6) Dellen– Localised area of conjunctival thinning – Commonly due to limbal approach
7) Necrotizing scleritis8) Refractive error– Most commonly astigmatism
9) Diplopia10)RD11)Scarring
11)Adhesive syndrome– Inferior oblique surgery
12)Under or over- corrections13)Gaze incomitance14)Alteration in palpebral fissure– Narrowing due to vt muscle resections – Large recess resect procedures of hz recti– Widening with large vertical recessions
15)Psychological complications
Post operative care after strabismus surgery
• Immediate general care• Dressing• Topical antibiotic and steroid• Oral antibiotics• Oral inflammatory• Restrictions for the patients• Follow up examination• Orthoptic treatment
ConclusionSquint Surgeries
Weakening
Recession
Marginal myotomy
Myectomy
Free tenotomy
Faden’s
Conjunctival recession
Strengthening
Resection
Advancement
Tucking
Harada- Ito
Transposition
Vertical transposition of horizontal muscles
Horizontal transposition of vertical muscles
Knapp
Hummelsheim
Jensen
Refrences
• Management of squint and Amblyopia– John A. Pratt-Johnson– Geraldine Tillson
• Strabismus and paediatric ophthalmology– Gary R. Diamond– Howard M. Eggers
• Squint and orthoptics– A.K. Khurana
Thank You