Background: Weakening of inferior oblique muscle has been used to treat some ocular motility disorders including inferior oblique overaction (IOOA) and dissociated vertical deviation (DVD). As inferior oblique muscle is the primary extorter of the eye, it is well known that inferior oblique weakening procedures affect fundus cyclotorsion. This study studies the effect of one of inferior oblique weakening procedures, inferior oblique anterior transposition (IOAT), on fundus cyclotorsion.

Aim of study: to study the effect of inferior oblique muscle weakening by anterior transposition surgery on fundus cyclotorsion by calculating disc-fovea angle using software on colored fundus photo.

Subjects and methods: this a prospective case series study conducted on a random group of patients with either IOOA (primary or secondary) or patients with DVD (either associated with IOOA or not).

Results: This study was conducted on 25 cases (48 eyes) with mean age 8.84 years (range; 2-24). IOOA and hypertropia (HT) decreased significantly from mean 2.5 ± 0.84 (range; 1-4) and 55 ± 20 PD (range;15-80) preoperatively to 1.17 ± 0.39 (range;1-2) and 15.64 ±10.08 (range; 0-30) (p < 0.001). Objective excyclotorsion, determined by calculation of the disc-fovea angle on colored fundus photo, decreased significantly from 12.67 ± 8.13 degree preoperatively, to 3.40 ± 5.06 degree (p < 0.001). During the follow-up period (mean; 9.16 months), only 2 cases (8%) developed post operative persistent defective elevation in abduction, or anti-elevation syndrome, as a post-operative complication.

Conclusion: IOAT surgery results in significant improvement of IOOA, HT with significant correction of fundus excyclotorsion with mild side-effects.