The effect of external ocular compression on intraocular pressure following retrobulbar anesthesia

Thirty consecutive patients scheduled for cataract surgery were randomized to external compression with the Honan intraocular pressure (IOP) reducer or digital pressure. The average increase in IOP after retrobulbar injection of 4 ml of anesthetic was 6.20 mm Hg. This increase was followed by a rapid decline in IOP within the first 2 1/2 minutes, averaging 1.20 mm Hg +/- 0.70 below baseline level for the Honan group and 1.00 mm Hg +/- 0.96 below baseline level for the digital group. From 5 to 10 minutes after injection there was a more gradual decline in IOP that averaged 0.35 mm Hg/min in the Honan group and 0.36 mm Hg/min in the digital group. After 10 minutes of external compression the IOP was 5.73 mm Hg +/- 0.96 below baseline level in the Honan group and 4.67 mm Hg +/- 0.64 below baseline level in the digital group. No statistical difference between the IOP measurements of the two groups was observed at 2 1/2 minutes at 5 minutes, or at 10 minutes.