Posters

V-pattern esotropia and hypertropia with significant excyclotorsion after cataract surgery secondary to inferior oblique myotoxicity from peribulbar anaesthesia

Poster Details

First Author: F.Yang SINGAPORE

Co Author(s):    F. Foo                    

Abstract Details

Purpose:

We present a unique case of inferior oblique myotoxicity secondary to peribulbar anaesthesia presenting with a V-pattern esotropia, hypertropia and significant excyclotorsion. Diplopia resolved and alignment improved following strabismus surgery on the horizontal recti combined with inferior oblique graded anteriorisation.

Setting:

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore

Methods:

Case report. A 71-year-old man developed vertical, horizontal and torsional diplopia following uneventful left cataract surgery under peribulbar anaesthesia, administered inferotemporally. Best-corrected visual acuity was 6/7.5 in both eyes. Prism and alternate cover testing demonstrated a V-pattern esotropia and a left hypertropia of 8 prism diopters. The left hypertropia increased on right gaze but was unchanged with head tilt to either side. Extra-ocular movements were intact with inferior oblique overaction of +1.5 in the left eye. Subjective excyclotorsion was 20 degrees on double Maddox rod testing, with corresponding excyclotorsion of the left fundus on indirect ophthalmoscopy.

Results:

Lancaster red-green testing demonstrated the V-pattern esotropia, hypertropia and excyclotorsion of the left eye. Neuroimaging and tests for thyroid function and myasthenia gravis were unremarkable. The diagnosis of left inferior oblique contracture secondary to myotoxicity was made. The patient underwent strabismus surgery and intraoperative forced duction testing demonstrated a correspondingly tight left inferior oblique muscle. Bilateral medial rectus recession was performed with left inferior oblique graded anteriorisation to a point 3.5mm posterior to the insertion of the inferior rectus. Post-operatively, the patient was orthophoric and diplopia resolved.

Conclusions:

Although most cases of vertical strabismus following cataract surgery have been attributed to vertical rectus muscle injury, inferior oblique contracture secondary to anaesthetic myotoxicity should also be considered as a possible cause. In particular, the presence of significant excyclotorsion relative to the amount of vertical deviation is suggestive of oblique muscle dysfunction.

Financial Disclosure:

NONE