What is the most commonly damaged muscle during lower lid blepharoplasty?

Most Commonly Damaged Muscle in Lower Lid Blepharoplasty

The inferior rectus muscle is the most commonly injured extraocular muscle during lower eyelid blepharoplasty. 1

Incidence and Clinical Significance

• The overall incidence of strabismus after blepharoplasty remains very low at under 3%, but when it occurs, the inferior rectus is predominantly affected 1
• In one surgical series examining diplopia after transconjunctival blepharoplasty, the inferior rectus and inferior oblique muscles were equally injured (4 of 6 cases each), with the lateral rectus encountered in one case 2
• A separate study of 12 patients with acquired strabismus following cosmetic blepharoplasty found that 7 patients developed incomitant vertical deviation consistent with inferior rectus paresis, while 5 had superior oblique palsy 3

Mechanisms of Injury

The inferior rectus is vulnerable through multiple pathways during lower lid blepharoplasty:

• Direct surgical trauma from excessive cautery, hemorrhage, and misdirected dissection during the procedure 1
• Anatomical proximity - the transconjunctival approach provides a much more direct route to the inferior extraocular musculature compared to transcutaneous surgery 2
• Scarring and fat adherence in the periorbital tissues can restrict muscle movement and contribute to injury 1
• Intramuscular hemorrhage and edema, cicatricial changes within the muscle, and accidental incorporation of extraocular muscle in closure of orbital septum 2

Clinical Presentation and Timing

• Patients with inferior rectus injury typically present with vertical diplopia that is often incomitant, making prism correction rarely satisfactory long-term 1
• Local hemorrhage without permanent loss of function may cause transient symptoms 1
• Many cases improve after 8 to 15 months if the injury results from local trauma or hemorrhage without significant scarring 1

Critical Management Timeline

If diplopia has not resolved or demonstrated improvement within 6 months of the blepharoplasty procedure, spontaneous resolution becomes unlikely and referral to a strabismus specialist should be made. 1

• Persistent diplopia beyond 6 months is unlikely to resolve spontaneously and warrants surgical intervention consideration 1

Anatomical Vulnerability Context

• The inferior rectus muscle is also the most commonly affected muscle (70% of cases) following retrobulbar or peribulbar anesthesia used in various ocular procedures, demonstrating its consistent anatomical vulnerability in the periocular region 1