J Korean Ophthalmol Soc.  2015 Mar;56(3):413-419. 10.3341/jkos.2015.56.3.413.

Contralateral Inferior Oblique Muscle Overaction after Unilateral Inferior Oblique Weakening Procedures

• Jang JW
• Kyung SE

• KMID: 2339048
• DOI: http://doi.org/10.3341/jkos.2015.56.3.413

Abstract

PURPOSE
To investigate the effect of unilateral inferior oblique weakening procedures on contralateral inferior oblique muscle functions and factors that may have an effect on contralateral inferior oblique muscle overaction (IOOA).
METHODS
A retrospective chart review was conducted of medical records of 40 patients who underwent unilateral inferior oblique (IO) muscle weakening procedures from 2007 to 2011 and were observed during a follow-up period of more than 6 months. These patients were composed of primary IOOA (4 patients), secondary IOOA due to superior oblique muscle (SO) palsy (21 patients), secondary IOOA due to inferior rectus muscle palsy (1 patient), and dissociated vertical deviation (DVD) accompanied with IOOA (14 patients). Factors that may have an effect on contralateral IOOA after undergoing the operation were assessed.
RESULTS
There were 7 patients (17.5%) who had over +2 IOOA after operation. IOOA on contralateral eye was increased from average of +0.00 to average of +0.66 +/- 0.14 in 6 months after operation (p < 0.01). There were no statistically significant differences between preoperative factors and functional changes in contralateral IO muscle.
CONCLUSIONS
There were no statistical factors that may have an effect on contralateral IOOA but the possibility of masked SO palsy before performing unilateral IO weakening procedures should be considered. In patients who have unilateral DVD associated with IOOA or small hypertropia, the contralateral IOOA can be more definite after operation; thus caution should be taken before operation.

Keyword

Inferior oblique muscle overaction; Unilateral inferior oblique weakening procedures

MeSH Terms

Follow-Up Studies
Humans
Masks
Medical Records
Paralysis
Retrospective Studies
Strabismus

Figure

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  Figure 1. The patient with masked bilateral superior oblique palsy who underwent inferior oblique recession in the left eye shows right inferior oblique overaction.

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  Figure 2. The patient with superior oblique palsy and 6 prism diopters of hypertropia with 25 prism dipoters of exotropia who received inferior oblique recession and lateral rectus recession in right eye shows mild limitation of elevation in the operated eye (circle) and contralateral IOOA (arrow). IOOA = inferior oblique muscle overaction.

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  Figure 3. The patient who underwent inferior oblique recession in the left eye shows limitation of elevation, elevation in abduction and adduction and prominent inferior oblique overaction in the right eye.

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  Figure 4. The patient with unilateral dissociated vertical deviation who received inferior oblique anteriorization in the left eye 5 years ago shows combined dissociated vertical deviation in the right eye and inferior oblique overaction.

Reference

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