Strabismus Surgery

Etiology

Idiopathic, restrictive strabismus may be seen with thyroid disease, secondary to scleral mass

The most common pediatric eye surgery

Goal to correct misalignment of eyes

• Weakening of the muscles (recession, marginal myotomy, or insertion of spacer)
• Strengthening of muscles (shortening their length, tightening)
• Transposing muscles

Surgery can be performed on any of the six eye muscles (rectus and oblique)

Forced Duction Test

A forced duction test is performed to determine whether the absence of movement of the eye is due to a neurological disorder or a mechanical restriction and is often performed in cases of either exotropia (outward eye deviation) or esotropia (inward eye deviation). If a patient has exotropia, a forced duction test might reveal a tight medial rectus muscle (responsible for inward eye movement), preventing the eye from aligning properly. For patients with esotropia, the test could indicate a tight lateral rectus muscle (responsible for outward eye movement), causing the eye to deviate inwards. The anesthetized conjunctiva is grasped with forceps, and an attempt is made to move the eyeball in the direction where the movement is restricted. If a mechanical restriction is present, it will not be possible to induce a passive eyeball movement.

Preoperative considerations

Position

Supine

Surgical Time

20-90 min

Morbidity

Failure to achieve desired alignment, infection, hemorrhage, anterior segment ischemia

Pain Score

2-4

Anesthetic Considerations

The procedure can be performed with local anesthesia if the patient is cooperative, although, for children, it is more likely general anesthesia will be required

• Note, no succinylcholine within 20 minutes of the test, as succinylcholine causes contraction of extraocular muscles

Ask the surgeon if they want neuromuscular blockade

PONV common

• Avoid nitrous post-induction
• Give Zofran 0.15 mg/kg
  • CTZ, Solitary tract, stomach
• Metoclopramide 0.1 mg/kg up to 10 mg
  • Dopaminergic - CTZ, solitary tract
  • Increases LES and stomach emptying
• Decadron - 0.15 mg/kg up to 5 mg
• Hydration - consider LR 30 mL/kg

Monitor the effect of sevoflurane

• If bradycardia during induction, pre-medicate with glycopyrrolate 0.01mg/kg

Atropine readily available 10 mcg/kg, minimum 100 mcg IV

Increased risk of malignant hypertension due to musculoskeletal abnormalities (strabismus, ptosis)

• Obtain a thorough family history

Oculocardiac reflex

Consider deep extubation with oral airway - prevent coughing