Changes in angular deviation before and after general anesthesia and strabismus surgery were examined.

Twenty patients with intermittent exotropia who were operated on by the same surgeon from January 2014 to October 2017 were included. The basic angle of deviation (preoperative angle of deviation, PreAn) was measured at an outpatient clinic. While lying on a surgical bed under general anesthesia, the bispectral index was referenced, and it was confirmed that there was a sufficient degree of sedation. Photographs were then taken at a height of 40 cm (angle of deviation under general anesthesia, PostAn); while still under general anesthesia, the same procedure was followed immediately after the end of surgery. At 6 months after surgery, the angle of deviation was measured.

There were 10 males and 10 females, and the mean age was 7.31 ± 3.59 years. The preoperative angle of deviation was 30.0 ± 13.87 prism diopters (PD) at far fixation; under general anesthesia, 26.46 ± 5.39 PD. There was a significantly positive correlation between the PreAn and angle of deviation under general anesthesia (PostAn - PreAn = −7.67 × PreAn + 19.57; R² = 0.872; p < 0.00). The angle of deviation changes between pre- and post-anesthesia (PostAn-PreAn) and at the end point of surgery (OP end) and at 6 months after surgery (6mon) also showed a significantly positive correlation (6mon-OP end = 0.317 × [PostAn - PreAn] + 13.098; R² = 0.334; p = 0.01).

There was a significant positive correlation between the measured angle of deviation pre- and post-anesthesia. We could estimate the degree of change between the angle of deviation immediately after surgery and the stable angle according to the degree of deviation before and after general anesthesia.