Contractile properties of superior rectus muscles were analyzed at twitch stimulation frequency. For naïve controls (control), the superior rectus muscles contralateral to the CNTF-treated muscles (contra), and the CNTF-treated muscles (CNTF), calculations were performed for (A) time to 50% relaxation, (B) time to 100% relaxation, and (C) maximum rate of relaxation. * Indicates significantly different from naïve control superior rectus muscles at P < 0.05.