Session: Poster session B

The Effect of Graded Inferior Oblique Z-Lengthening Partial Width Myotomy for Small Hypertropias with Cyclotorsion

 

Introduction: Treating small incomitant hypertropias can be challenging and can cause overcorrection. Z lengthening myotomy of the inferior oblique has been described previously. The study describes the surgical technique and examines the effect of graded inferior oblique Z lengthening partial width myotomy for incomitant hypertropias.



Methods: A retrospective chart review was performed to identify patients who underwent graded inferior oblique Z lengthening partial width myotomy for small incomitant hypertropias with cyclotorsion from January 2021 to August 2023. One to five alternating partial width myotomies 1 mm apart were performed on the inferior oblique of the hypertropic eye.



Results: 12 patients were identified. Mean hypertropia in primary gaze improved from 3.2±1.8 Δ to 0.2 ± 0.6 Δ. Ipsilateral horizontal gaze hypertropia improved from 1.9±1.7 Δ to 0 Δ. Contralateral gaze improved from 6.5±3.3 Δ to 0.5 ± 1.0 Δ. Up to five degrees of excyclotorsion were resolved in three patients. One patient had an overcorrection. Regression analysis showed that for each 1mm of partial width myotomy, the effect was 1.18Δ in primary gaze (P<.01) while .65 in contralateral gaze and .42 in ipsilateral gaze, which were not statistically significant



Conclusion: Graded Inferior oblique Z lengthening partial width myotomy for small hypertropias has a favorable result in collapsing hypertropias and improving primary deviation. It is a relatively straightforward, quick, sutureless procedure. In our small sample size, the risk of overcorrection was small. The number of partial width myotomies can be graded to accommodate the amount of hypertropia.



References: 

Kızıltoprak H, Yaşar HH, Tekin K. The Effect of Inferior Oblique Muscle Z-Myotomy in Patients with Primary Inferior Oblique Overaction. Turk J Ophthalmol. 2020;50(2):82-86.