[Diplopia complicating peribulbar anesthesia for cataract surgery and early use of MRI].

OBJECTIVE: To evaluate the early use of magnetic resonance imaging (MRI) for the diagnosis of diplopia following cataract surgery under peribulbar anaesthesia.

STUDY DESIGN: Single centre prospective study.

PATIENTS AND METHOD: From January 2003 to January 2005 every patient undergoing cataract surgery under peribulbar anaesthesia was included. Any patient spontaneously complaining of double vision on day 1 received a full ophthalmologic examination. When binocular diplopia was confirmed by a positive Hess-Lancaster test, the patient immediately underwent an MRI.

RESULTS: During the two year period, 4805 patients underwent cataract surgery under peribulbar anaesthesia. Eight patients reported double vision on day 1 (0.16% prevalence). Clinical examination confirmed binocular diplopia and a positive Hess-Lancaster test identified the paralysed muscle. In 7 out of 8 patients, the MRI performed on the same day showed a T2 hyper intensity signal within the paralysed muscle, it was interpreted as inflammatory oedema following an accidental intra muscular injection of a myotoxic local anaesthetic. In one patient the MRI was normal, suggesting a preoperative undiagnosed diplopia having no relation to the peribulbar anaesthesia.

CONCLUSION: A slit-lamp exam and a Hess-Lancaster test are necessary to confirm postoperative strabismic diplopia after cataract surgery. An early MRI can accurately distinguish postanaesthetic myotoxic diplopia from a preoperative diplopia revealed by the corrective cataract surgery.