Surgical Management in ET Flashcards
What is Recession / Resection surgery?
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
When would we do a recession/resection surgery?
E.g. 30PD Nr & 30PD Dist would do a recess and resection to straighten the eye
Why would we do bi-medial recessions?
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
When would we do single muscle surgery?
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
What are the aims of surgery
in constant ET with & without accommodative element?
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
In constant ET, when the deviation is approximately equal at near and distance what surgery do we do?
Unilateral MR recession / LR resection
What surgery do we do for a constant deviation that’s greater at near with a small distance angle?
Bi MR recession
What surgery do we do in cases of bilateral LR laxity in myopic ET?
Rare but bilateral LR resection
When would we need to do 3 - 4 procedures?
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)
When would we do unilateral MR recession / LR resection?
In constant ET
Deviation approx. equal Nr & Dist
When would we do bimedial MR recession?
In constant ET
When the deviation is greater for near (small distance angle)
When would we do a bilateral LR resection?
in constant ET rarely when there’s a case of bilateral LR laxity in myopic ET
In ET without accommodative elements when onset is <30mo what do we expect for the outcome of surgery?
Unlikely to develop stereopsis following ocular alignment (Chan et al., 2012)
In ET without Accommodative Element, when onset is >44mo what do we expect for the outcome of surgery with no amblyopia?
More likely to develop good level of stereoacuity
In ET with Accommodative Element and onset is >36mo what do we expect the surgical outcome to be?
More likely to develop good level of stereopsis (Lordanous et al., 2015)
Thomas & Guha (2010) - in ET and XT, if <70PD how many muscles should we operate on?
2;
Bilateral MR recession
OR
MR recession/LR resection
= 68% success rate
Thomas & Guha (2010) - in ET and XT, if equal to or >70PD how many muscles should we operate on?
3;
Bilateral MR recession/LR resection
67% success with 3 muscles
40% when only 2 muscle surgery
Thomas & Guha (2010) - in ET and XT, when is there a reduced BSV outcome in patients?
If amblyopic (33% success rate)
Poorer outcome in older age
When is deterioration in early-onset ET likely?
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
What surgery would we do in fully accommodative ET?
Surgery only required if decompensated
In convergence excess ET when near angle >25PD & significant angle for distance (>10PD) what surgery do we do?
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
What is the Faden procedure?
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.
When may intermittent ET’s require surgery?
Non-accommodative types that relate to distance & time
In Near ET what surgery should we use?
- 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
