THE EFFECT OF PNEUMOPERITONEUM ON INTRAOCULAR-PRESSURE IN RABBITS WITH ALPHA-CHYMOTRYPSIN-INDUCED GLAUCOMA

Increased intraperitoneal pressure is associated with physiological ch anges including alterations of intraocular pressure (IOP). We have pre viously shown that IOP is not adversely affected by increased intraper itoneal pressure up to 15 mm Hg in women with no preexisting eye disea se. The aim of this study was to measure IOP changes associated with i ncreased intraperitoneal pressure (up to 15 mm Hg) of 2 h duration in 12 rabbits with alpha-chymotrypsin-induced glaucoma. A reliable model of glaucoma was created by injecting alpha-chymotrypsin into the poste rior chamber of the right eye in 12 rabbits. Thereafter, 5 of the 12 r abbits with glaucomatous eyes were treated with topical timolol. The l eft eye was used as a control. During pentobarbital general anesthesia , increased intraperitoneal pressure up to 15 mm Hg was created by int raperitoneal CO2 insufflation. Body temperature and expired CO2 were k ept constant throughout the study. IOP measurements were made using an electronic pneumotonometer. IOP, mean arterial pressure, heart rate, and central venous pressure were recorded in head-up and head-down pos itions before, during, and after increased intraperitoneal pressure. T he IOP of both eyes, in both treated and untreated rabbits, increased significantly from baseline only when increased intraperitoneal pressu re associated with the head-down position resulted in a significant in crease in central venous pressure. However, the IOP increase remained within the diurnal range. The major finding of this study is that, in a reliable model of glaucoma, CO2 pneumoperitoneum was associated with an increase in IOP when a head-down position was combined with pneumo peritoneum. Implications: In rabbits with alpha-chymotrypsin-induced g laucoma, increased intraperitoneal pressure (up to 15 mm Hg) resulted in a significant intraocular pressure increase when pneumoperitoneum w as associated with the head-down position. However, the intraocular pr essure increase remained within the diurnal range.