Effect of unilateral inferior oblique weakening on fundus torsion in bilateral eyes of children with congenital superior oblique palsy.

AIM To study the change of torsion in both eyes after unilateral inferior oblique (IO) weakening on children with congenital superior oblique palsy (SOP). METHODS This retrospective study enrolled all patients diagnosed with unilateral congenital superior oblique palsy (UCSOP) accompanied by inferior oblique overaction (IOOA). A total of 120 eyes of 60 patients were divided into group 1 (more extorted paretic eye) and group 2 (more extorted nonparetic eye). The degree of fundus torsion was evaluated before and 1mo after the IO weakening procedure. The torsion of the fundus was recorded by measuring the disk-foveal angle (DFA) using fundus photography. RESULTS Group 1 included 26 cases and group 2 included 34 cases, thus the rate of extorsion was insignificantly higher in the nonparetic eye (P=0.10). The preoperative DFA in the paretic and nonparetic eyes was 13.21±5.95, 7.97±4.25 in group 1, and 4.65±3.79, 13.16±5.35 in group 2 (both P<0.001). The postoperative DFA in the paretic and nonparetic eyes was 8.57±4.87, 7.32±4.27 in group 1 (P=0.24), and 3.85±6.00 and 9.94±5.45 in group 2 (P<0.001). The amount of postoperative reduction of the DFA in the paretic and nonparetic eyes was 4.64±3.90, 0.65±0.76 in group 1 (P=0.002), and 0.80±0.81, 3.21±5.50 in group 2 (P=0.01). The difference in the amount of reduction of DFA in the more extorted eye in group 1 (paretic eye) vs group 2 (nonparetic eye) was insignificant (P=0.30). CONCLUSION Excyclotorsion in the nonparetic eye has a similar probability in the paretic eye in UCSOP children, and weakening of the ipsilateral IO has a more obvious effect on the decrement of extorsion in the more extorted eye regardless of which eye is paretic.