Fig. 1From: Evaluation of the effect of the mouth gag use on optic nerve sheath diameter of pediatric patients undergoing tonsillectomy or Adenotonsillectomy: An observational studyCalculation of the degree of neck extension by measuring the angle between the Frankfort plane (the imaginary line passing from left orbital to left porion point) and horizontal plane of the operation table in the natural position. The degree neck extension is measured 121.72 degrees in this figureBack to article page