Strabismus after regional anesthesia for cataract surgery.

Background: An adult strabismus clinic in a regional eye centre provided an opportunity to estimate the risk of postoperative diplopia from regional anesthesia after cataract surgery and to describe the management of these patients.

Methods: Retrospective cohort analysis. All cases were referred over a 22-month period (November 1997 to September 1999) for investigation of postoperative diplopia after cataract surgery. The surgical and anesthetic records were reviewed to determine the number and location of injections, and the volume and type of regional anesthesia. The evolution and management of patients' diplopia was studied prospectively.

Results: Twenty-one patients (12 women and 9 men aged 63 to 88 [median 76] years) were ascertained with postoperative diplopia. In 11 cases the right eye was affected, and in 10 cases, the left eye. Vertical diplopia occurred most commonly from inferior rectus restriction (16 cases). Three cases resolved without treatment, which indicated that the diplopia was transient. Four patients declined treatment, five required prism in eyeglasses only, and nine required strabismus surgery. One patient required surgery and prism in eyeglasses. Two patients required more than one strabismus operation to relieve the diplopia. For the period of data collection, we estimate the risk of nontransient postoperative diplopia from regional anesthesia as 2.6 cases per 1000 cataract procedures (95% confidence interval 1.9-4.7).

Interpretation: Patients should be forewarned of the risk of diplopia after cataract surgery with regional anesthesia. The treatment of the diplopia may require prism in eyeglasses or strabismus surgery or both.