To evaluate the change in hyperdeviation according to position change in patients with vertical strabismus.

The authors measured the hyperdeviation in 32 patients with vertical strabismus at 6 m, 2 m, and 33 cm in the seated position and at 2 m and 33 cm in the supine position using the alternate prism cover test.

The mean amount of hyperdeviation in the seated position was 6.31±6.27 PD at 6 m, 6.31±6.27 PD at 2 m, and 3.69±6.65 PD at 33 cm. The mean hyperdeviation in the supine position was 6.09±6.37 PD at 2 m and 3.55±6.36 PD at 33 cm. There was no significant difference in hyperdeviation according to the change of position at the same measuring distance. No significant difference between the hyperdeviation at 6 m in the seated position and 2 m in the supine position was found ( P >0.05).

The hyperdeviation at 6 m and 33 cm in the seated position can be replaced by hyperdeviation at 2 m and 33 cm in the supine position during adjustable suture surgery for vertical strabismus.