Surgical Management in ET

Question 1

What is Recession / Resection surgery?

Answer 1

When one muscle = Recession = Muscle is moved back

When the other muscle = Resected = section of eye muscle to be removed and then attached in the same place so the only difference is the shorter length of the EOM

A recession/resection of one muscle means it’s shortened and then reattached further back from the front of the eye

Question 2

When would we do a recession/resection surgery?

Answer 2

E.g. 30PD Nr & 30PD Dist would do a recess and resection to straighten the eye

Question 3

Why would we do bi-medial recessions?

Answer 3

Targets near angle so is operating on both MR muscles which is considered less risky than recess / resect so used in Near ET or Convergence Excess ET

In children can get good outcomes in infantile ET so a safer procedure & is reversible compared to resected procedures

Question 4

When would we do single muscle surgery?

Answer 4

Single MR recession for small angles (between 10 to 20PD) to give them a bit more control. Usually do a recession.

When there’s ARC they may not require surgery as may have gross BSV and some stereopsis

Question 5

What are the aims of surgery
in constant ET with & without accommodative element?

Answer 5

1) Improve Ocular Alignment
When poor cosmesis and NRC the treatment is aimed at making the deviation less noticeable

• Make deviation less noticeable
• Slightly under-correct angle
  (residual ET) by approx. 10PD BO
• Perform PODT in all patients >7yo

2) Restore BSV

Same procedures where there is potential for BSV

Question 6

In constant ET, when the deviation is approximately equal at near and distance what surgery do we do?

Answer 6

Unilateral MR recession / LR resection

Question 7

What surgery do we do for a constant deviation that’s greater at near with a small distance angle?

Answer 7

Bi MR recession

Question 8

What surgery do we do in cases of bilateral LR laxity in myopic ET?

Answer 8

Rare but bilateral LR resection

Question 9

When would we need to do 3 - 4 procedures?

Answer 9

In constant ET with large angle, IO o/a (overaction) & V-pattern
(staging procedures to see how they respond to each one, better chance of success, rarely operate on more than 3 muscles in one go across the 2 eyes)

Question 10

When would we do unilateral MR recession / LR resection?

Answer 10

In constant ET
Deviation approx. equal Nr & Dist

Question 11

When would we do bimedial MR recession?

Answer 11

In constant ET
When the deviation is greater for near (small distance angle)

Question 12

When would we do a bilateral LR resection?

Answer 12

in constant ET rarely when there’s a case of bilateral LR laxity in myopic ET

Question 13

In ET without accommodative elements when onset is <30mo what do we expect for the outcome of surgery?

Answer 13

Unlikely to develop stereopsis following ocular alignment (Chan et al., 2012)

Question 14

In ET without Accommodative Element, when onset is >44mo what do we expect for the outcome of surgery with no amblyopia?

Answer 14

More likely to develop good level of stereoacuity

Question 15

In ET with Accommodative Element and onset is >36mo what do we expect the surgical outcome to be?

Answer 15

More likely to develop good level of stereopsis (Lordanous et al., 2015)

Question 16

Thomas & Guha (2010) - in ET and XT, if <70PD how many muscles should we operate on?

Answer 16

2;
Bilateral MR recession
OR
MR recession/LR resection

= 68% success rate

Question 17

Thomas & Guha (2010) - in ET and XT, if equal to or >70PD how many muscles should we operate on?

Answer 17

3;
Bilateral MR recession/LR resection

67% success with 3 muscles
40% when only 2 muscle surgery

Question 18

Thomas & Guha (2010) - in ET and XT, when is there a reduced BSV outcome in patients?

Answer 18

If amblyopic (33% success rate)

Poorer outcome in older age

Question 19

When is deterioration in early-onset ET likely?

Answer 19

Dickey and Scott (1988) reported 77% deteriorated where onset occurred in 1st year of life, frequency of deterioration increases with longer delay between onset and prescription of glasses

Baker and Parks (1980) found that 50% of cases deteriorated and required surgery

Question 20

What surgery would we do in fully accommodative ET?

Answer 20

Surgery only required if decompensated

Question 21

In convergence excess ET when near angle >25PD & significant angle for distance (>10PD) what surgery do we do?

Answer 21

Bi MR recession (possibly with Faden procedure) OR unilateral surgery recessing the MR and resecting LR if distance angle is particularly large & may require orthoptic treatment to achieve optimum result

Question 22

What is the Faden procedure?

Answer 22

In convergence excess ET when near angle >25PD & significant angle for distance (>10PD). It’s the ‘posterior fixation suture’ designed to limit the action of the muscle or at least make the muscle “work harder” in it’s field of action while producing minimal or no effect in primary position. The principle of the posterior fixation is to reduce the lever arm of a rectus muscle crippling the muscle somewhat in its field of action. By “working harder”, the muscle receiving the Faden “sends” increased innervation to its yoke muscle by Hering’s law.

Question 23

When may intermittent ET’s require surgery?

Answer 23

Non-accommodative types that relate to distance & time

Question 24

In Near ET what surgery should we use?

Answer 24

• Bimedial recession with or without loop sutures
• Posterior fixation sutures on both MR with or without recession on MR

Post-op may have to strengthen BSV with prisms and orthoptic exercises

Question 25

What is posterior fixation suture also known as?

Answer 25

Faden Procedure or Retroequatorial Myopexia

Question 26

In Distance ET, what surgery do we recommend?

Answer 26

Aim is to slightly over-correct for a better long-term outcome.

• Bilateral LR resections
• Asymmetrical LRresect / MR recess
• Unilateral LR resect / MR recess (if large angle)

Question 27

What surgery would we do in age-related distance ET?

Answer 27

Yadav et al (2014) suggested single muscle LR resection is effective in age-related distance ET

Question 28

What surgery should we do in Cyclic ET?

Answer 28

Need to fully correct the manifest anfle of the deviation through:
- Unilateral MR recession / LR resection
- Bilateral MR recessions
- Weakening procedure of both IO, if bilateral IO o/a’s & significant V-pattern is present

Recommended to perform the surgery whilst the ET is cyclic and may be resolved through horizontal strabismus surgery and can reoccur when surgery is delayed

Question 29

What is a comitant ET?

Answer 29

A comitant esotropia has nearly the same degree of deviation in every position of gaze

Question 30

What is an incomitant ET?

Answer 30

An incomitant esotropia have a deviation that varies between gazes

Question 31

Diagnosis and Management for:
Cgls N: 35 RET
Cgls D: 30 RET
Sgls N: 45-50 RET
Sgls D: 45 RET

Answer 31

Diagnosis: Constant ET with accommodative element

Surgical Mx: Unilateral MR recession/LR resection as close near and distance angles

Question 32

Diagnosis & Management for:
sgls: 70 L / Alt ET
Sgls: 70 L/Alt ET
With IO over-actions

Answer 32

Diagnosis: Cyclic or Constant ET or Infantile ET -> need further information

Surgical Mx: Cyclic = weakening procedure of both IO due to IO o/a’s. Surgery whilst cyclic. If Constant ET unilateral MR recession / LR resection

Question 33

Diagnosis & Management for:
Cgls N: 30 RET
Cgls D: 8 E
Sgls N: 45 RET
Sgls D: 18 RE(T

Answer 33

Diagnosis: Smaller with glasses at NR and Dist angle controlled to a a latent with glasses, Dist angle smaller than than Nr = Intermittent. Has an accommodative element but not fully corrected and controlled to esophoria at Dist with glasses so a Convergence Excess Esotropia

Surgical Mx: Target near angle through bimedial recessions