Rat extraocular muscle regeneration. Repair of local anesthetic-induced damage
B. M. Carlson and E. A. Rainin
Local anesthetics that are commonly used in ophthalmic surgery (0.75%
bupivacaine hydrochloride, 2.0% mepivacaine hydrochloride, and 2.0%
lidocaine hydrochloride plus 1:100,000 epinephrine) were injected into the
retrobulbar area of rat eyes. Controls were injected with physiological
saline. All three anesthetics produced massive degeneration of the
extraocular muscles. Muscle degeneration is followed by regeneration of the
damaged muscle fibers. In addition to muscle damage, severe damage was also
seen in harderian glands, especially after exposure to mepivacaine and
lidocaine plus epinephrine. With these findings in rats, it is hypothesized
that the temporary diplopia sometimes seen in patients after ophthalmic
surgery might be due to anesthetic-induced damage to the extraocular
muscles.
