Comparison of the immediate with the 24-hour postoperative prism and cover measurements in adjustable muscle surgery: is immediate postoperative adjustment reliable?

PURPOSE Immediate postoperative adjustment after adjustable-suture strabismus surgery has been suggested as a viable alternative to the classic adjustment that is performed, usually within 6 to 24 hours after surgery. The purpose of this study was to compare the immediate postoperative eye measurements with those taken 24 hours postoperatively and to determine whether there was any significant difference between the 2 measurements. METHODS This was a prospective study of strabismus patients who were candidates for muscle surgery using the adjustable-suture technique. All patients received a total intravenous general anesthesia, which allowed rapid recovery of consciousness. Measurements using the simultaneous prism cover test were obtained in the recovery room immediately after the patients regained consciousness and again 24 hours after surgery. Both measurements were taken before adjustment and were compared. RESULTS A total of 25 patients were studied. The postoperative alignment changed significantly during the first 24 hours in 84% of our patients. The mean drift in alignment during the first 24 hours measured 7.2 +/- 4.3 prism diopters and was significantly different from 0 ( P < 0.001). CONCLUSION The immediate postoperative ocular alignment after adjustable strabismus surgery is significantly different from the 24 hours postoperative alignment. This difference was noticed despite using an anesthesia protocol that allowed rapid recovery and full regaining of consciousness shortly after the conclusion of surgery. This early drift should be taken into consideration if adjustment is to be made in the immediate postoperative period.