[Efficacy of surgery on congenital nystagmus with convergence damping]

To evaluate the efficacy of surgery in the treatment of congenital nystagmus with convergence damping.

Retrospective and comparative case series. Eight patients diagnosed as congenital nystagmus with convergence damping at Beijing Children's Hospital between September 2010 and September 2012 were enrolled in this study. The ages were 9.5 (12, 6) years old, and follow-up was 9 (24, 6) months. All patients received prism induced convergence and the same surgery of bimedial rectus recession and bilateral rectus tenotomy. The best corrected visual acuity, the range of fusion and the nystagmus waveforms were analyzed before and after surgery.

The range of fusion was -3.75±1.83° to +19.38±3.16° before surgery and -3.88±1.55° to +19.00±3.02° after surgery; there was no significant difference (t=0.24, P=0.82). The binocular visual acuity increased from 0.21±0.15 without convergence to 0.28±0.18 using convergence; there was significant difference (t=-4.43, P=0.00). The visual acuity was 0.32±0.20 after surgery, significantly different from that before surgery without convergence (t=-5.29, P=0.00), but not significantly different from that before surgery using convergence (t=-2.12, P=0.07). Patients had significant improvements in the frequency (t=3.28, 3.02, P<0.05) and intensity of the nystagmus waveforms when using convergence and postoperatively (t=3.27, 3.48; P<0.05), but there was no significant improvement in the amplitude of the waveforms (t=1.31, 1.57, 0.31, P>0.05).

Surgery for congenital nystagmus with convergence damping can provide expectations for ocular motor and visual results. The range of fusion should be wide enough, and the effect of convergence on the frequency is greater than that on the amplitude.