Abstract
Purpose :
A modification of the Harada-Ito procedure, disinserting and advancing the anterior fibers of the superior oblique (SO) tendon, with or without resection, with or without an adjustable suture, is often the procedure of choice when addressing symptomatic excyclodeviation. Few data are available on the dose-response relationship with this procedure and on whether the changes in torsional alignment are long-lasting, which would influence the target for adjustment.
Methods :
21 patients underwent a unilateral Harada-Ito advancement of the anterior fibers of the SO (1/3 to 3/4 width), with or without resection (0 to 7 mm), with or without advancement (0 to 10 mm) to the superior border of the lateral rectus, and with or without adjustment (-2 to 7 mm), yielding a net total dose (resection + advancement + adjustment) of 3 to 13 mm. Pre- and post-op torsion was measured using double Maddox rods. The target post-adjustment alignment was a small incyclodevation, with adjustment performed the same day as surgery. We calculated change in cyclodeviation from pre-op to post-adjustment, and a Spearman rank correlation coefficient between surgical dose and change in cyclodeviation. We also calculated the change in torsion from post-adjustment up to 5 years post-op.
Results :
Pre-op, excyclodeviation ranged from 5° to 17°, mean 8.8°±3.2° SD. Post-adjustment cyclodeviation ranged from 0° to 9° of incyclo. Some cases could not be adjusted to the planned target incyclodeviation due to suture placement. Change in torsion from pre-op to immediate post-adjustment was 7° to 20° of incyclotorsional effect, with a positive correlation between dose and torsional effect (rs = 0.55, P=0.01). Mean unwinding of incyclotorsional effect was 3.5°±2.5° between post-adjustment and day 1 and 2.7°±2.4° between day 1 and 6 weeks. Unwinding slowed after 6 weeks, with a mean change of -0.2°±2.7° between 6 weeks and 1 year (n=13) and 3.7°±2.1° between 1 year and 5 years (n=3). Total unwinding was 6.2°±2.9° at 6 weeks, 6.5°±4.1° at 1 year and 6.8°±2.1° at 5 years.
Conclusions :
The unilateral adjustable Harada-Ito procedure with resection can induce up to 20° of incyclotorsional effect in a titratable manner. The effect of this procedure regresses over time, and, based on our data, an immediate post-adjustment target angle of 7° incyclodeviation appears to be desirable.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.