Diplopia after Cataract Surgery

Ophthalmology Volume 113, Number 9, September 2006 Hamada et al reported that most cases of anesthesia-related diplopia presented within the early postoperative period.1 All 3 of our patients presented to their local ophthalmologists with diplopia within 1 week of cataract surgery, demonstrating a clear temporal association between the onset of diplopia and the local anesthesia injection. In addition, they all complained of pain after local anesthetic injection. One patient commented that the anesthetic injection was notably more painful during her second eye cataract surgery, which subsequently developed diplopia. Pain may be indicative of direct trauma to an extraocular muscle by the sharp needle or inadvertent injection of the anesthetic injection into a muscle, causing excessive stretching and pain. Two patients recollected receiving ⱖ2 injections. Details of the anesthetic agent used, the exact technique, and sites of injection were not available to us. This becomes particularly significant as cataract surgery in the United Kingdom increasingly is being performed by temporary centers employed by the government to reduce waiting times for surgery. Complete details of anesthesia and surgery may not be made available from these centers, and therefore, when patients present to their local eye units with diplopia the diagnosis may be difficult to make unless there is a broad awareness of this condition. Hamada et al suggest that the inferior rectus is most commonly involved, and all our cases presented with a vertical deviation and limitation of the inferior rectus.1,2 Because our cases presented to us ⬎6 months after the anesthesia, a restrictive pattern of decreased mobility was noted. In the acute setting, it would be easy to mistake lateral/inferior rectus limitation as a neurogenic palsy prompting unnecessary investigations. Swelling and edema of the muscle on imaging will help to distinguish a traumatic myogenic palsy from a neurogenic palsy. As these myogenic palsies may recover spontaneously, expectant management with prisms and/or monocular occlusion is recommended. Surgical intervention should be delayed for up to 6 months after anesthesia, once measurement stability is achieved. In our experience, an inferior rectus recession works well. In summary, features that may help the general ophthalmologist to identify a patient with anesthesia-related diplopia are as follows: (1) a temporal association with the anesthetic event, (2) pain during injection of anesthetic agent, (3) vertical binocular diplopia with inferior rectus limitation (a less common presentation is with horizontal diplopia and lateral rectus muscle involvement), and (4) either spontaneous recovery or evolution into a restrictive myopathy. If hyaluronidase is protective against anesthesia-related diplopia, its withdrawal from clinical practice may increase the incidence of this condition.1–3 It is therefore important for general ophthalmologists to be aware of peribulbar anesthesia– related diplopia and maintain a high index of suspicion to enable accurate diagnosis. NISHANT KUMAR, MRCOPHTH ROXANE HILLIER, MRCOPHTH IAN MARSH, FRCOPHTH Liverpool, United Kingdom

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References 1. Hamada S, Devys JM, Xuan TH, et al. Role of hyaluronidase in diplopia after peribulbar anesthesia for cataract surgery. Ophthalmology 2005;112:879 – 82. 2. Strouthidis NG, Sobha S, Lanigan L, Hammond CJ. Vertical diplopia following peribulbar anesthesia: the role of hyaluronidase. J Pediatr Ophthalmol Strabismus 2004;41:25–30. 3. Brown SM, Brooks SE, Mazow ML, et al. Cluster of diplopia cases after periocular anesthesia without hyaluronidase. J Cataract Refract Surg 1999;25:1245–9.

Dear Editor: We were surprised to read that Dr Hamada et al found such a high incident rate of diplopia after cataract surgery during a time when hyaluronidase was not available in their surgical center.1 In a similar scenario, we reported our experience with referred cases of postoperative diplopia from 7202 cataract surgeries performed in a regional eye center over a 22-month period from November 1997 to September 1999.2 During that time, from April 1998 to November 1998 hyaluronidase was not available to our center. We compared the number of referred cases of postoperative diplopia during the times when hyaluronidase was and was not available and found no difference, suggesting that hyaluronidase was not a factor. Whereas we evaluated overall 2.6 cases of postoperative diplopia per 1000 cataract surgeries, Hamada et al found 7.4 cases per 1000 cataract surgeries when hyaluronidase was not available, and no cases when hyaluronidase was available. This higher rate may reflect better capture of patients who had transient diplopia, who were underrepresented in our series. Hamada et al reported the anesthetic volume and number of injections in all cases of diplopia. They noted that 71% of their diplopia cases required more than one injection. Does this number of injections differ significantly from that with the patients who did not experience diplopia? Was there a significant difference in the volume and number of injections between patients who received hyaluronidase and those who did not? We agree with the authors that the complications of retrobulbar anesthesia have in many cases prompted surgeons to opt for topical anesthesia as the preferred method of analgesia. Surgeons and anesthetists must be reminded that lidocaine is myotoxic. IAN M. MACDONALD BRADLEY J. WAKEMAN Edmonton, Canada GEORGE F. REED Bethesda, Maryland References 1. Hamada S, Devys JM, Xuan TH, et al. Role of hyaluronidase in diplopia after peribulbar anesthesia for cataract surgery. Ophthalmology 2005;112:879 – 82. 2. MacDonald IM, Reed GF, Wakeman BJ. Strabismus after regional anesthesia for cataract surgery. Can J Ophthalmol 2004;39:267–71.