A case of superior oblique myokymia observed by an image-analysis system

Superior oblique myokymia is a microtremor of the eye that causes monocular torsional oscillopsia. A modified Harada-Ito procedure was used to treat a case of the disease in a 20-year-old woman. The authors used video-image analysis pre- and postoperatively to evaluate the effect of the surgery on abnormal torsional eye movements. This analysis revealed that before surgery, the abnormal torsional movement had a very regular cycle (duration of attack, 8.0 +/- 0.5 s; time interval between attacks, 18.7 +/- 3.2 s; n = 9). After the surgery, amplitude of the abnormal torsional eye movement was reduced, and the oscillopsia had subjectively improved, although the movement cycle remained unchanged. The authors' video-image analysis, which used iris striation, proved to be a useful method for clinical measurement of torsional eye movements.