Fixation of extraocular muscles in the rabbit by means of a cyanoacrylate adhesive

Purpose - To evaluate in a rabbit model a new surgical technique for weakening the extraocular muscles, which involves neither recession nor suturing. Methods - In each of the eyes of 12 adult rabbits, the superior rectus muscle was fixed to the underlying sclera by means of octyl 2-cyanoacrylate adhesive, which was applied to both sides of a Silastic strip (4 mm × 3 mm × 0.5 mm) that was inserted beneath the belly of the muscle. Two, four, eight and ten weeks after surgery the treated muscles were subjected to macroscopic and histological examinations. Results - At two weeks the muscle-strip-sclera complex was surrounded by a thin translucent sheath; histological examination of the muscles showed extensive inflammatory proliferation with leukocytes. After 4 weeks the muscle presented a tendon-like appearance, and histological examination revealed an extensive leukocyte infiltration, which was followed (8 and 10 weeks) by the appearance of fibrous tissue, which gradually replaced almost all of the muscle fibres in the segment that had been attached to the strip. Conclusion - These findings indicate that this technique produces progressive fibrosis of the portion of the extraocular muscle that is glued to the Silastic strip. It is possible to hypothesize that a loss of elasticity and contractile strength caused by this fibrosis will produce a muscle-weakening effect similar to that obtained with surgical recession.