hi guys hope this helps.

1. PG - Puneeth Isloor
Moderator – Dr. Shubhashree Karat

2. ANATOMY AND ACTIONS
 Easy mnemonics – SIN RAD
and SLIM
Muscle Primary
action
Secondary
action
Tertiary
Action
SR Elevation intorsion Adduction
IR Depression extorsion Adduction
SO Intorsion depression Abduction
IO Extorsion elevation Abduction
MR Adduction - -
LR Abduction - -

3. Blood supply – Ophthalmic artery
Muscular arteries (2)
Medial .M.A Lateral .M.A
Supplies MR,IR ,IO Supplies LR,SR,SO,LPS
anterior ciliary arteries - emerge on orbital surface from these
muscular arteries - 10 -12 mm from the insertions
2 anterior ciliary arteries from all muscles except LR
The blood supply of IO muscle enters it just lateral to IR – this
neurovascular bundle can get disinserted while recessing IO

4. CONCEPT OF ARC OF CONTACT
 The point at which the tendon first touches globe –
Tangential point
 The arc of contact is distance between the tangential
point and the centre of anatomic insertion of the muscle
 MR – 6 mm , LR – 15 mm , SR-8.4mm, IR-9mm
 Power of a muscle is proportionate to its arc of contact
hence recession weakens muscle by reducing arc

5. When a muscle contracts , it produces a force that rotates the
globe
The rotational force α length of the moment arm (m)
rotational force α force of muscle contraction (F)
Rotational force = m × F

6. General goals of strabismus surgery
 To restore binocular vision
 To improve ocular alignment
 To enlarge the field of single binocular vision
 To alleviate an abnormal head posture
 To improve the aesthetic appearance of patient
Goals should be prioritised based on the cause of strabismus.

7. PRE-OPERATIVE ASSESSMENT
 History – Rule out neurological diseases
- Previous family photographs(FAT)
- Document time of onset of strabismus
- Past anesthestic complications and bleeding
diatheses
-Past history of trauma
-Past history of strabismus surgery elsewhere

8.  Pre op Examination –
 Look for nystagmus , anomalous head posture
 Lid abnormalities – epicanthus ,ptosis,telecanthus
 Visual acuity recording
 Cycloplegic refraction
 Anterior segment – Look for conjunctival scars,blebs
- Scleral buckle, scleral ectasia
Fundus – Macular pathology , Chorioretinal scarring

9.  Identify if eccentric fixation is present
 Test for ductions and versions and vergences
 FDT and FGT in adults pre-operatively
 Orbital imaging – only in case of thyroid myopathy and
slipped or lost muscle .Not routinely done.
 Anesthesia – GA
- LA in adults – Sub tenon’s is preferred.

10. [

11. ANATOMICAL CONSIDERATIONS – GENERAL PRINCIPLES
 Distance of each rectus muscle from limbus must be taken into
consideration.
 The muscle insertions at new locations must be splayed and
not narrow – otherwise central sag occurs.
 While performing vertical transpositions of horizontal recti
,care should be taken to keep the muscle shift concentric to
limbus.
 Never operate on 3 muscles at once – to reduce risk of anterior
segment ischemia

12.  Sclera is thinnest at insertion site of recti .Hence 0.5 mm
stump of muscle should be left for resection re-suturing
 Avoid damage to vortex veins and tenons during
supramaximal recessions involving posterior sclera
 Establish symmetry between two eyes if it doesn’t exist and
maintain it when it exists.
 In patients with high grade stereopsis , caution while
operating on SO – as it could induce vertical diplopia

13. INCISION TYPES
Fornix incision Limbal incision
 Fornix approach
- Preferred for surgery of oblique muscles
- Made at a point 8- 9 mm from the limbus
Advantages
- Access to more number of muscles at a time
-More patient comfort
-Less scarring
-Ease of construction and closure
Disadvantage – For large resections cannot resect conjunctiva
- Cannot approach posterior orbit if needed
- Increased risk of conjunctival tear

15. Limbal incision – Used for rectus muscle surgeries

16.  Strabismus surgery corrects ocular misalignment by at least
4 different mechanisms
- Slackening a muscle - Recession
-Tightening a muscle – Resection , plication
-Reducing moment arm – Faden procedure
-Changing vector force by transposition

17. STRABISMUS SURGERIES
 WEAKENING PROCEDURES OF RECTI
 STRENGTHENING PROCEDURES OF RECTI
 WEAKENING PROCEDURES OF OBLIQUES
 STRENGTHENING OF SUPERIOR OBLIQUE

18.  WEAKENING PROCEDURES OF RECTI MUSCLES
1)Conventional recession
2)Hang back recession
3)Adjustable suture technique
4)Retroequatorial myopexy (Faden)
5)Recession of vertical recti
6)Slanting recession
7)Marginal myotomy and myectomy

19. 1.CONVENTIONAL RECESSION
Principle –Moves the muscle insertion CLOSER to the
ORIGIN creating a muscle slack
 The muscle slack reduces muscle strength as per starling ‘s
length –tension curve
 It does not reduce the moment arm when eye is in primary
position
 The muscle should be re-inserted within the length of its
arc of contact
 Hence , there is maximum limit up to which a recession can
be done for each muscle

20.  A recession has its greatest effect in the
field of action of the muscle.
 On rotation of eye away
from recessed muscle ,
2 things happen
- Recessed muscle slack is
reduced
- The recessed muscle is
inhibited by reciprocal
inhibition(Sherrington s law)

21. Procedure
 Anesthesia
 Lids retracted by self retaining speculum
 FDT done
 Limbal conjunctival incision is made and two radial
incisions made at the ends of the limbal incision
 The intermuscular septum is button holed
 The jameson s hook and the green s hook are passed
underneath the muscle

22.  Check ligaments and intermuscular septum are separated
 2 interlocking loops of 6-o vicryl are passed at the two ends
of muscle insertions
 Muscle is cut with tenotomy scissors leaving a stump of 0.5
mm
 Measurement of recession is made with callipers and the
recessed muscle is sutured at the new site

25. 2 .HANG BACK RECESSION
 Principle -Suspends the muscle back, posterior to scleral
insertion , with a suture to weaken the muscle.
 Small to medium sized recessions of 3- 6 mm can cause
overcorrection because of central muscle sag

26.  Indications
- A supramaximal recession is needed but unable to
pass suture posteriorly due to risk of scleral perforation
- Recession over a retinal buckle
- Recession over an area of scleral ectasia as in high myopes
- Large recession of a tightly contracted muscle
 Advantage – Needle passes through thick anterior sclera and
excellent exposure
 Disadvantage – Narrowing of muscle insertion causing central
muscle sag

28. 3. ADJUSTABLE SUTURE TECHNIQUE
Principle – Here recession allows fine –tuning of ocular
movements in the immediate post-op period
Procedure -Performed in 2 stages
 1st stage – GA or LA .Recessed muscle is sutured such that
the sutures can be made loose and muscle recession can be
varied.
 2nd stage – Readjustment is made within 24 hours of the
first surgery under local anesthesia.

29.  The adjustments can be made
using a bow-tie knot or by a
sliding noose
 Not recommended for children
less than 15 years of age as it
needs cooperation for
adjustment stage.

30. Indications
- Large angle strabismus where results are inconsistent
- Paralytic strabismus
- Restrictive diseases – Thyroid myopathy
- Previously injured extra-ocular muscles where
muscle function assessment may be inaccurate

31. 4. RETROEQUATORIAL MYOPEXY(FADENS)
- Principle -The muscle is sutured posterior to its
insertion farther than the limit of its arc of contact
- It shortens the lever arm
- It reduces the moment arm only when the eye rotates
towards the muscle sutured.

33.  It is usually combined with a muscle recession as its
weakening effect alone is not much
 Best suited for MR as it has the shortest arc of contact
 Works the least with LR as it has a long arc of contact
 Measurements for various muscles
- MR – 12- 14 mm
- LR - 16-20 mm
- SR and IR – 14-16 mm

34.  Indications for a Faden
- Paralytic strabismus – In case of a LR palsy ,Faden of
the contralateral MR is done .
Used when patient is orthotropic in primary position but
has diplopia on gaze towards paretic muscle.
- Duane ‘s retraction - Contralateral MR
- DVD – Superior recti
- Nystagmus blockage syndrome – MR
When combining with a recession , the muscle must be fixed
at a distance obtained by subtracting the Amount of
recession from the total faden.

35. 5. RECESSION OF VERTICAL RECTI
Principle – The check ligaments for the vertical recti
are linked to whitnall ‘s ligament for SR
lockwood’s ligament for IR
 Hence ,While recessing IR ,care must be taken to separate it
from lockwood s ligament and to prevent lower lid retraction
 Indications-
- DVD
- Thyroid myopathy
-Congenital fibrosis
Does not exceed 5mm in these 3 indications

36. 6. SLANTING RECESSIONS
 For esotropia,
 A- pattern : both MR recessed with Upper end> lower end
 V-Pattern : Both MR …..lower end > upper end
 Difference of 3-5 mm between the upper and lower ends
 For exotropia,
 A-Pattern : Both LR ……Lower end > upper end
 V –Pattern : Both LR …….Upper end > Lower end

37. 7.MARGINALMYOTOMY
Principle -Several cuts are made
alternatively at the two borders of
the muscle.
Indication – To weaken a muscle
that has been maximally recessed
 They are transverse cuts in the
muscle of atleast 2/3 width.
MYECTOMY – used only for
inferior oblique

38.  WEAKENING PROCEDURES OF RECTI
 STRENGTHENING PROCEDURES OF RECTI
 WEAKENING PROCEDURES OF OBLIQUES
 STRENGTHENING OF SUPERIOR OBLIQUE

39. TIGHTENING PROCEDURES ON RECTI
1. Resection
2. Advancement
3. Double-breasting or tucking
4. Transposition of adjacent muscles

40. 1.RESECTION
 It is the most common procedure for strengthening
 Involves excision of the tendinous part only
 If excess resection is done , it will weaken the muscle
 Hence
For MR – maximum limit is 6 mm
For LR - maximum limit is 8mm

41. Procedure
 Anesthesia
 Lids retracted by self retaining speculum
 FDT done
 Limbal conjunctival incision is made and two radial
incisions made at the ends of the limbal incision
 The intermuscular septum is button holed
 The jameson s hook and the green s hook are passed
underneath the muscle
 Check ligaments and intermuscular septa are separated

42.  Measurement of the resection is marked with calipers
ensuring that the muscle is not stretched
 Two double armed vicryl 6-0 sutures are passed through
muscle in an interlocking fashion
 A muscle clamp is applied 2 mm distal to sutures and the
green’s hook removed and muscle is resected and cut
leaving 0.5 mm stump
 Conjunctiva is re-apposed

46. 2. ADVANCEMENT
Principle- The muscle is re-inserted closer to
limbus , thus making it more taut - increases arc of
contact
Indications
- It is the ideal choice in a squint where recession has
been done earlier
- In paralytic squint , advancement may be combined
with resection

47. 3. DOUBLE BREASTING OR TUCKING
Principle -It shortens the muscle by folding the muscle and
suturing the folded muscle to muscle.
Indications -Commonly used for plication of the superior
oblique muscle in superior oblique palsy.
 The length of the tuck ranges from 6-12mm
Advantages over resection
 Muscle is not disinserted and anterior ciliary vessels are
not compromised
 It is reversible

48. 4.MUSCLE TRANSPOSITIONS
 Indications
- Paralytic strabismus
- Slipped or lost muscle
Various procedures are – Knapp ‘s procedure
- Jensen ‘s procedure
-Hummelsheim procedure

49. KNAPP ‘S PROCEDURE
 Indications
-Double elevator palsy
-Lateral rectus palsy
 MR and LR muscles are
transposed superiorly to
the insertion of SR
muscles
 A large posterior
dissection is needed to
separate it from the
intermuscular septum
and check ligaments

50. JENSEN ‘S PROCEDURE
 Indications – Lateral rectus palsy
 Here the adjacent muscles are
tied together 12 mm posteriorly,
but not disinserted
 Lateral halves of SR and IR are
dissected
 Upper and lower halves of LR are
dissected
 Lateral half of SR and upper half
of LR are sutured
 Lateral half of IR and lower half
of LR are sutured ADVANTAGE – Less chance of A/S
ischemia

51. HUMMELSHEIM’S
PROCEDURE
 It is a split tendon transfer
technique to preserve
anterior ciliary artery
perfusion
 Indications –
- Lateral rectus palsy
- Lost medial rectus muscle
 Lateral halves of SR and IR
are dissected upto 14 mm
from their insertion
 They are reinserted adjacent
to LR insertion and they
should touch the LR
insertion

52. Two modifications of the Hummelsheim are
 1)Augmented Hummelsheim – Brooks
Augmentation by resecting 4-6mm of transposed recti
It tightens the transposition.
Muscle union modification (Foster modification)
Transposed and paretic muscles are sutured together
and then to sclera , 4mm posterior to insertion.

53. Other transposition procedures
1)Callahan ‘s procedure –
Modification of jensen ‘s procedure used for elevator palsy.
Upper half of MR ----sutured to ---medial half of SR
Upper half of LR ----sutured to----lateral half of SR
2)O’Connor ‘s procedure – Here transposition of Vertical
recti to LR is combined with LR tucking

54. 5. VERTICAL TRANSPOSITION OF HORIZONTAL
RECTI IN A-V PATTERNS WITHOUT OBLIQUE
DYSFUCNTION
 For A Pattern For V Pattern
 MR shifted up(BE) MR shifted down(BE)
 LR shifted down(BE) LR Shifted up (BE)
 MR up ,LR down in MR down ,LR up
monocular recession
-resection

56.  WEAKENING PROCEDURES OF RECTI
 STRENGTHENING PROCEDURES OF RECTI
 WEAKENING PROCEDURES OF OBLIQUES
 STRENGTHENING OF SUPERIOR OBLIQUE

57.  WEAKENING PROCEDURES OF INFERIOR OBLIQUE
Indications –
1)Superior oblique palsy (Ipsilateral IO)
2)V – pattern with IO overaction (Both eyes IO)
3) Double elevator palsy (Contralateral IO)
4)Dissociated Vertical deviation

58. Four Procedures
1)Inferior oblique Recession
2)Anterior transposition with graded recession
3)Extirpation-denervation
4)Inferior oblique myectomy

59. 1)Inferior oblique recession - is of 2 types
- Fink ‘s method - Produces only slackening
- Park ‘s method –
Produces slackening plus mild anterior transpositioning
The IO is inserted at a point 2mm lateral and 3 mm posterior
to lateral end of IR insertion

60. 2)Graded recession - Anterior transposition
Recommended by Kenneth Wright for IO overaction
The basis is that the more anterior the IO insertion , the
greater the weakening effect
The more anterior the placement of IO insertion , the more
the muscle becomes a depressor
Complication of this procedure is the postoperative
limitation of elevation called “The anti elevation syndrome”
Overaction I .O Placement
+1 4mm posterior and 2 mm lateral to IR insertion
+2 3mm posterior to IR insertion
+3 1-2mm posterior to IR insertion
+4 At IR insertion

61. 3)Denervation and extirpation –
The nerve to IO is on posterior border of the muscle .
It can be hooked and cauterised
It results in laxity of muscle.
Can be combined with myectomy

62. 4) Inferior oblique myectomy
 It is faster to perform and does not need the muscle to be
sutured to the sclera – less risk of perforation
 Muscle is allowed to retract into the tenon s capsule and
the conjunctiva is closed

63. WEAKENING PROCEDURES OF SUPERIOR OBLIQUE
They are two in number
1) Superior oblique tenotomy
2)Superior oblique tendon expander of Wright
Indications for both – Brown’ syndrome

64.  Approach to SO – Through fornix incision

65. 1.SUPERIOR OBLIQUE TENOTOMY
 Should be performed nasal to SR
muscle
 A temporo-conjunctival incision
is made and reflected nasally –
This helps in many ways
1)To keep the nasal intermuscular
septum intact and reduce tendon
scarring down to sclera
2)To reduce the incidence of post
operative SO palsy which occurs with
temporal tenotomies (because they scar
down to sclera)

66. 2)SUPERIOR OBLIQUE
TENDON EXPANDER OF
WRIGHT
Principle : Controls the separation
of the ends of tendon, allowing
quantification of tendon
separation
A segment of silicone 240 retinal
band is inserted between the cut
ends of SO tendon .
The first suture is placed 3 mm
nasal to the superior rectus
The maximum length of band is
7mm.Most can be managed with
5-6mm length of band.

68.  WEAKENING PROCEDURES OF RECTI
 STRENGTHENING PROCEDURES OF RECTI
 WEAKENING PROCEDURES OF OBLIQUES
 STRENGTHENING OF SUPERIOR OBLIQUE

69. SUPERIOR OBLIQUE MUSCLE STRENGTHENING
 SO can be functionally divided into
- Anterior 1/3 – Intorsion
- Posterior 2/3 – Depression
and abduction
- Best accessed through fornix incision
- Mainly two procedures
1)Harada-Ito –Procedure
2)Superior Oblique tendon tuck

70. 1.Harada – Ito procedure
Principle -Tightening the anterior fibres will induce
intorsion without too much change in depression and
abduction.

71.  Indication - a partially recovered SO palsy where there is only
large degree of extorsion
 It is of 2 types
-1)Fell’s modificied Disinsertion technique – anterior fibres are
disinserted and moved anteriorly and laterally
then sutured at 8 mm posterior to superior border of LR insertion
-2)Classic Harada –Ito – here the fibres are looped with a suture
and displaced laterally

73. 2. Superior Oblique tendon tuck
Indications –Usually done for congenital superior oblique palsy
Also for traumatic superior oblique palsy
If too tight a tuck , then iatrogenic browns syndome is seen
Avoided by doing intraoperative FDT

74. COMPLICATIONS OF STRABISMUS SURGERY
INTRAOPERATIVE POST-OPERATIVE
Operation of wrong eye and wrong
muscle
Orbital cellulitis
Hemorrhage Suture granulomas
Scleral perforation Conjunctival cysts
Central sag Dellen
Muscle sheath ,tendon rupture and
fat prolapse
Over correction and
undercorrection
Loose sutures in the muscle Vomiting
Slipped or lost muscle Anterior segment ischemia

75. LOST MUSCLE OR SLIPPED MUSCLE
 Most commonly affects MR and is difficult to retrieve
 MR has no fascial connections to obliques to prevent it from
retracting posteriorly
 Can occur if the muscle slips during disinsertion and if the
sutures have not been applied correctly
 A slipped muscle occurs when a muscle retracts posterior to
the intended recession
 Lost muscle can also occur after orbital trauma or
hemorrhage

76. Signs of lost muscle
-Limited ductions
-Widening of lid fissure in the field of action of muscle
Management
- Find the muscle and surgically advance it to anterior
sclera
- If not retrieved , then a transposition procedure must
be performed – Hummelsheims for MR.

77. ANTERIOR SEGMENT ISCHEMIA
-Rare , but serious complication
-Occurs if 3 or more recti surgery are done at a time
especially in adults with atherosclerosis and hyperviscosity
-Occurs in cases with previous radiotherapy and previous RD
surgeries
-Two vertical recti should not be operated with one horizontal
rectus and especially the LR
-The obliques do not contribute much to this

78. Signs
- Corneal edema
- Corneal thinning
- Severe anterior uveitis
- Iris atrophy
- Distorted pupil
- Cataract and phthisis
in late stages
Treatment – Steroids –local
and systemic