Related Experiment Video
Updated: Jul 12, 2026
Efficiently Recording the Eye-Hand Coordination to Incoordination Spectrum
Published on: March 21, 2019
Quantitative eye movement recordings in a patient with acquired bilateral superior oblique palsy before and after a
Howard S Ying1, Bejan Darbandi, Xiaoyan Shan
1Department of Ophthalmology, The Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA. hying1@jhmi.edu
Purpose:
We examined the effects of the Harada-Ito procedure on static and dynamic alignment in an adult with acquired bilateral superior oblique palsy (SOP).
Methods:
3D eye movements were recorded before and six weeks after a bilateral Harada-Ito procedure. Superior oblique muscle (SOM) size and contractility were assessed with orbital imaging.
Results:
On MRI, the left SOM was smaller than the right. Little contractile thickening was present in down gaze for either eye. Preoperatively, the patient had a hypertropia: 1.9 degrees right hypertropia (at down 20 degrees , left 20 degrees ) and 6.4 degrees left hypertropia (at down 20 degrees , right 20 degrees ). Postoperatively, the vertical tropia in all positions was < 1 degrees . Listing's primary position rotated toward straight ahead for the RE but was unchanged for the LE. Postoperatively, for 40 degrees upward saccades peak dynamic intrasaccadic extorsion decreased by 2.2-3.2 degrees for both eyes and for 40 degrees downward saccades by 2.3-3.6 degrees for the RE but was unchanged for the LE. Saccade conjugacy improved and post-saccadic drift lessened for all vertical saccades.
Conclusions:
The Harada-Ito procedure produced striking improvements in static and dynamic alignment in bilateral SOP. Some changes were binocular (decreased post-saccadic drift, improved saccade conjugacy, less dynamic extorsion for upward saccades) but others were much greater in the less paretic eye (torsional gradients from up to down gaze, less dynamic extorsion for downward saccades). Both central adaptive and peripheral mechanical changes explain these findings. Our results also imply that the Harada-Ito procedure has more effect when there is residual function of the SOM.
