SURGERIES

Question 1

EFFECT OF Muscle weakening

Answer 1

*Doesn’t cause limitation of movement (unless more than recommended maximum sx)
*Effect greatest in field of action
*Amount of recession depends on the muscle
*Recession is most common rectus muscle weakening procedure

Question 2

OBLIQUE RECESSION

Answer 2

○ One side of muscle is recessed more than the other

Question 3

TRANSPOSITION

Answer 3

Insertion of horizontal recti raised or lowered to weaken more in up-gaze or down-gaze

Question 4

Augmented recessions

Answer 4

Loop recession
*Muscle maximally recessed and reattached by loop sutures through corners of tendon
*Useful in persistent ET

Hang- loose recession
*Muscle disinserted and reattached to its original insertion using extended sutures

Question 5

Tenectomy/ tenotomy

Answer 5

Muscle weakened by complete or partial tenectomy or tendon space or expander

SO muscle - Browns, A pattern XT, Completed 3NP

Question 6

Myectomy

Answer 6

Segment of muscle cut out and muscle is released to allow retraction back into tenons capsule

Question 7

Myotomy

Answer 7

Used to augment effect of recession
Muscle lengthened by transverse incisions

Question 8

Posterior fixation suture (faden procedure)

Answer 8

○ Produce progressive weakening as the eye moves into the field of action
○ Reduces lower arm action progressively
○ Only used on MR, SR, IR

USED IN LR PALSY, CONV EXCESS, INFANT ET C FT, DVD
Considerable experience needed to perform

Question 9

Further weakening procedures for IO

Answer 9

• Extirpation
  Disinsertion

Question 10

Effect of Strengthening procedures

Answer 10

Muscles shortened and strengthened
Maintains its action through point of original insertion
Maximum amount of resection to avoid restrictions

Resection preferrable to advancement (muscle moved forwards towards limbus)
- More effective
- Muscle more visible through sclera

Cannot reverse resection
Never used in TED
More reaction post op than most surgery
Advancement only used on recessed muscle that has overcorrected angle

2 methods
1. Sutures woven through muscle belly and required distance
- Muscle in front cut off
- Shorter muscle reattached at original insertion

2. Muscle tendon grasped 
- Tendon cut close to globe
- Sutures through tendon and muscle belly at required distance 
- Tied and anterior unused portion cut off

Question 11

SO TUCK

Answer 11

• Strengthens muscle by folding termina muscle and tendon
  
  • Muscle not disinserted
  • Sutures through muscle belly at required point and passed through tendinous insertion, tightened and tied
  • Rarely on rectus
  • SO - advancement and resection tricky and unreliable
  • Normally cant tuck SO more than 8mm
  • Useful in SO palsy when HoT greatest in downgaze
  • Great risk of causing iatrogenic browns syndrome

Question 12

what is TRANSPOSITION surgery

Answer 12

Movement of part/ whole muscle(s) to alter its 1 or 2 degree action
Used in muscle paralysis or severe paresis
RECTUS MUSCLES ONLY (very rarely SO and IO)

Aim to realign deviating eye in PP
Movement in direction of paralysed muscle not greatly improved

Question 13

WHOLE MUSCLE TRANSPOSITION

Answer 13

Horiz or vertical muscles transposed singly

IPSILATERAL PAIRS e.g. RLR and RMR
	- Rotate eye in direction of transposition 
	- Transposed asymetrically to alter A and V patterns and correct cyclotorsion 

CONTRALATERAL PAIRS e.g. RMR, LLR
	- Contralateral pairs transposed symmetrically 

INDICATIONS 
- A + V patterns - transpose horiz recti, combined with recess/resect 
- Horiz transposition of vert recti - correct cyclotropia 
- LR paralysis 
- SR and IR transposed and lower poles of LR insertion
- Duanes - type A
- MR paralysis
- Lost muscle 

Knapp - moving MR and LR adjacent to SR for elevation deficiency 
Inverse Knapp - moving MR and LR to IR for depression deficiency

Question 14

PART MUSCLE TRANSPOSITION

Answer 14

• Only half of muscle is transposed, reducing risk of ant. Segment ischaemia
  
  • Usually two muscles involved and transposed to a third
  Indications
  - Muscle paralysis - double elevator palsy - elderly px with poor blood supplyLR stabalisation
  - Used for upshoot and downshoots in duanes retraction
  - Prevents globe from slipping over ipsilateral LR on attempt ADD
  - Jampolsky (1984) advised recession and splitting of LR, half of muscle above insertion, half below

Question 15

SO TRANSPOSITION

Answer 15

Harada-ITO procedure
- Increases intorting action of SO without affecting depression and abduction - often in bilateral SO palsy
- Anterior 1/3 of SO tendon disinserted and split about 10mm up. Mobilised portion reattached 8mm posterior to LR insertion

Question 16

Hummelsheim

Answer 16

• Lateral halves of uperior and inferior recti disinserted
  
  • Medial and lateral fibres of each muscle are seperated posteriorly
  • Lateral half reinserted alongside upper and lower poles of lateral rectus

Original hummelsheim - suture transposed section of muscle directly to LR muscle
Current method - suture transposed muscle to sclera adjacent to paralysed muscle

Augmented
- 5mm of tranposed muscle resected before suturing to sclera

Question 17

Jensen

Answer 17

• Transposition without disinsertion
  
  • Maintains ant segment blood supply
  • 3 adjacent rectus muscles split in half along muscle fibres
  • For LR - lateral halves of sup and inf tied loosely to upper and lower halves of split LR close to equator
  · Muscle hook used to split muscle – two equal halves
  · Aim to keep one ciliary vessel undisturbed in portion of each vertical rectus muscle not being transposed
  · Nonabsorbable suture looped around adjacent muscle segments and tied
  · Too tight - damage to the rectus muscles and blood supply
  · Too loose – anterior migration of suture causing muscle slippage

Question 18

Hummelshein vs Jenson

Answer 18

Biomechanical modelling (Lee et al. 2018)
Able to model different transposition surgeries on the same model eye with LR palsy
Hummelscheim 40.8% reduction in deviation (28^BO)
Jensen 49.4% reduction in deviation (34^BO)