Effect of bottle height on the corneal endothelium during phacoemulsification.

To directly measure intraocular pressure (IOP) in simulated phacoemulsification and to assess the usefulness of lowering the bottle height in protecting the corneal endothelium in clinical phacoemulsification.Nippon Medical School Hospital, Tokyo, Japan.Simulated phacoemulsification was performed in porcine eyes with 2 bottle heights, 65.0 cm (BH 65 group) and 19.0 cm (BH 19 group). The IOP was continuously measured with a microprobe. In a clinical study, phacoemulsification was performed with a bottle height of 60.0 cm (BH 60 group) and of 30.0 cm (BH 30 group). One day, 1 week, and 1 and 3 months after surgery, cell density and corneal volumes were measured using specular microscopy and rotating Scheimpflug photography, respectively.In the simulation study, IOP fluctuated between 50 mm Hg and 60 mm Hg in the BH 65 group and between 20 mm Hg and 30 mm Hg in the BH 19 group. In the clinical study of 31 eyes, the rate of cell density decrease was significantly lower in the BH 30 group than in the BH 60 group at all time points. The rate of increase in corneal volume was significantly lower in the BH 30 group than in the BH 60 group at 1 month.Intraoperative IOP in phacoemulsification with a usual bottle height appeared to exceed the normal range. Phacoemulsification with a low bottle height was less harmful to the corneal endothelium.