The connective tissue power of extraocular muscles

Abstract

Introduction: Eye movements have long held a fascination for clinicians, neuroanatomists, neurophysiologists, and recently, bioengineers. Our aim was to study ocular motility after extraocular muscle (EOM) disinsertion. Methods: Forty strabismus surgeries were done for 40 adult volunteers (20-45 years). All surgeries were completed under either topical anesthesia using lidocaine 2% jelly or peribulbar sensory-motor differential blocking anesthesia using ropivacaine 0.2%. These surgeries involved disinserting 64 rectus and 6 oblique muscles, after locking them using 6-0 vicryl. After disinserting each muscle, the patient was asked to move his eye in the field of action of this muscle and eye movement was recorded as normal, reduced, or absent. Results: Normal eye movement was attained after disinserting 50 rectus muscles (87%), while the other 14 rectus muscles (13%) showed reduced eye movement. On the other hand, the six oblique muscles (100%) gut normal eye movement after disinsertion. None of the muscles showed absent eye movement after disinsertion. Discussion: The unexpected, strong, persistence of eye movement in the direction of action of the disinserted muscle signifies the anatomic insertion not only occurs at the point at which the muscle blends into the sclera but also involves the area of muscle attachment to the surrounding connective tissue. A thorough knowledge and management of these attachments may be the key to successful strabismus surgery in some cases like unexpected residual esotropia or exotropia and persistence of dissociated vertical deviation after superior rectus recession. Conclusions: Orbital connective tissue is an important additional locomotor system which requires special microsurgical techniques.