Squint surgeries

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