Effect of bilateral inferior oblique partial myectomy on V pattern exotropia with inferior oblique overaction

BMC Ophthalmol. 2022 May 21;22(1):230. doi: 10.1186/s12886-022-02456-1.

Abstract

Purpose: To compare the effect of bilateral inferior oblique partial myectomy on V-pattern exotropia patients with bilateral symmetric inferior oblique overaction (IOOA) and asymmetric IOOA.

Methods: This was a retrospective study including 53 V-pattern exotropia patients with bilateral IOOA of all grades who underwent bilateral inferior oblique partial myectomy. Success was defined as the elimination of the IOOA and the collapse of the V pattern at the final follow-up. The fovea-disc angle (FDA) and V-pattern exotropia were compared before and after surgery.

Results: This study included 53 V-pattern exotropia patients, containing 29 patients with symmetric IOOA (Group I) and 24 patients with asymmetric IOOA (Group II). The last follow-up ranged from 3 to 16 months (mean of 5 months). After myectomy, 3 eyes in Group I and 2 eyes in Group II were observed with residual grade 1 IOOA. The surgical success rates of IOOA correction in Group I and Group II were 96% and 95%, respectively. The difference was not statistically significant (P = 0.808). V-pattern exotropia collapsed with residual 2 (min. 0, max. 6) PD for Group I and 2 (min. 0, max. 10) PD for Group II, and there was a statistically significant difference between pre- and postoperative V-pattern exotropia in the two groups (P = 0.000). No inferior oblique (IO) underaction or antielevation syndrome (AES) was found in either group. The average preoperative FDA of the right eye and the left eye was (8.93 ± 4.34)° and (10.86 ± 4.27)° in Group I and (9.08 ± 4.92)° and (11.00 ± 5.69)° in Group II. There was a significant difference in preoperative FDA between the right eye and the left eye in the two groups (Group I p = 0.029; Group II p = 0.038).

Conclusions: Bilateral inferior oblique partial myectomy can bring "symmetric" effectiveness in the correction of IOOA and FDA. It can potentially be used as a safe and successful treatment for V-pattern exotropia with bilateral IOOA. In addition, the FDA may be a promising index for evaluating fundus extorsion.

Keywords: Fovea-disc angle; Inferior oblique overaction; Inferior oblique partial myectomy; V-pattern exotropia.

MeSH terms

  • Exotropia* / surgery
  • Eye Movements
  • Humans
  • Muscular Diseases*
  • Ocular Motility Disorders*
  • Oculomotor Muscles / surgery
  • Ophthalmologic Surgical Procedures
  • Orbital Diseases*
  • Retrospective Studies
  • Strabismus* / surgery
  • Treatment Outcome
  • Vision, Binocular