Complex Squint (Strabismus) Surgery | PristynCare

Risk Factors

Risk factors for complex and recurrent strabismus include:

• Prior strabismus surgery with muscle scarring
• Cranial nerve palsy from any cause
• Thyroid eye disease with progressive muscle fibrosis
• High myopia with heavy eye syndrome
• Congenital ocular motor syndromes (Duane, Moebius)
• Neurological conditions affecting eye movement control

Who is a Candidate

Adults with diplopia significantly affecting quality of life, patients with cosmetically significant large-angle squint, and children with amblyogenic strabismus not correctable with glasses or prisms are candidates for surgery. Stable strabismus (unchanged angle for at least 6 months) is preferred before planning surgery.

Diagnosis

Pre-operative evaluation for complex strabismus surgery includes:

• Full orthoptic assessment including cover-uncover test, alternate cover test, and prism cover test
• Measurement of deviation in all positions of gaze
• Binocular vision assessment including stereopsis testing
• Duction and version assessment for restrictive or paralytic strabismus
• Forced duction test under anesthesia to differentiate restrictive from paralytic causes
• MRI of the orbit and brain if cranial nerve palsy or neurological cause is suspected

Treatment Plan

Medical treatment options (prisms, vision therapy, botulinum toxin) are exhausted before surgery is planned. Surgical planning involves determining which muscles to operate on, the amount of recession and resection, and whether adjustable sutures are appropriate. For paralytic strabismus, transposition procedures or Botox may be used before definitive surgery. Adjustable suture technique allows post-operative fine-tuning to maximize alignment outcomes.

Strabismus Surgery Steps

Complex strabismus surgery typically involves the following steps:

• General anesthesia for children; local anesthesia with sedation or adjustable suture technique for adults
• A peritomy incision is made through the conjunctiva to expose the extraocular muscle
• The muscle to be weakened is isolated with muscle hooks
• Recession: the muscle is detached from its insertion and reattached further back on the globe
• Resection: the antagonist muscle is shortened and reattached at its original insertion
• For adjustable sutures: a slip knot is placed instead of a permanent suture; alignment is adjusted the following morning
• Transposition: for paralytic strabismus, the adjacent muscles are transferred to a new insertion point
• Conjunctiva is closed with absorbable sutures

Recovery After Surgery

Recovery after strabismus surgery involves:

• Eye redness and discomfort are common for 2 to 4 weeks post-operatively
• Use prescribed antibiotic and steroid eye drops for 4 weeks
• Adjustable suture adjustment is performed the morning after surgery under topical anesthesia
• Return to school or work is typically possible within 1 week
• Avoid swimming for 4 weeks and contact sports for 6 weeks
• Vision therapy or prisms may be needed after surgery to consolidate binocular vision

Risks and Complications of Strabismus Surgery

Possible complications of complex strabismus surgery include:

• Undercorrection or overcorrection: Residual or new misalignment requiring further surgery or prisms
• Reoperation: Required in 20 to 30% of complex cases for fine alignment
• Anterior segment ischemia: Reduced blood supply to the anterior eye from operating on multiple muscles simultaneously
• Lost muscle: Muscle slips off the sclera during surgery, requiring emergency exploration
• Infection: Endophthalmitis or orbital cellulitis, though very rare
• Induced torsion: New rotational misalignment from transposition procedures
• Persisting diplopia: Double vision may remain in extreme positions of gaze even after good primary position alignment