RESUMEN
Lower blepharoplasty is a challenging aesthetic procedure. Despite advances in clinical and neuroanatomical studies related to orbicularis oculi muscle innervation, no study has examined its histopathological aspects in different lower blepharoplasty procedures. This study aimed to assess changes in the pretarsal muscle complex in patients treated with transcutaneous lower blepharoplasty with orbicularis myotomy versus those treated with transconjunctival blepharoplasty without myotomy. METHODS: A total of 268 patients underwent blepharoplasty performed by a single surgeon: transcutaneous lower blepharoplasty in 112 (41.7%) and transconjunctival lower blepharoplasty with retroseptal access in 156 (58.2%). Subsequent minor blepharoplasty procedures were performed in 32 patients with lower pretarsal orbicularis oculi muscle biopsy. Connective tissue, fibrillar elastic system, nerves, blood vessels, fiber diameter, and sarcomeres were analyzed. RESULTS: Without myotomy: collagen, 9.46 ± 0.41%; elastin, 7.03 ± 0.62%; blood vessels, 4.25 ± 0.06%; nerves, 5.2 ± 0.55%; fiber diameter, 62 ± 8.0 µm; and sarcomere, 1.9 ± 0.11 µm. With myotomy: collagen, 19.02 ± 1.66%; elastin, 7.88 ± 1.10%; blood vessels, 5.13 ± 0.70%; nerves, 2.9 ± 0.48%; fiber diameter, 49 ± 6.5 µm; and sarcomere, 1.8 ± 0.17 µm. DISCUSSION: Excess endomysial connective tissue, particularly between muscle fibers, should be considered pathological. The pathological changes in the pretarsal muscle complex after blepharoplasty with myotomy may have resulted from innervation interruptions as well as vascularization blockages. CONCLUSIONS: Surgeries with myotomy caused significant changes in collagen, nerves, and muscle fiber diameter. These observations strongly suggest the superiority of a technique that preserves orbicularis oculi muscle integrity. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .