Pressure differential of intraocular pressure measured between supine and sitting position.

In 177 eyes, an average rise in the intraocular pressure of 6 mm Hg was found between the sitting and supine positions. These pressures were measured with the pneumatonograph--an instrument that allows measurement of intraocular pressure in both positions. The pressure rise upon lying down (over that in the sitting position) was significant at the 1% level.