Aqueous volume loss associated with occlusion break surge in phacoemulsifiers from 4 different manufacturers.

PURPOSE

To evaluate aqueous volume losses associated with occlusion breaks at varying vacuum limits in phacoemulsification systems from 4 different manufacturers.

SETTING

Alcon Research Ltd., Lake Forest, California, USA.

DESIGN

Experimental study.

METHODS

The anterior chamber was modeled using the spring eye model. Systems tested included the Centurion, Whitestar Signature, Stellaris PC, and EVA. Occlusion breaks were actuated at vacuum limits of 200, 300, 400, 500, and 600 mm Hg and a target intraocular pressure of 55 mm Hg.

RESULTS

The model eye piston reached its measurement limit just below 600 mm Hg on the EVA and just above 400 mm Hg on the Stellaris PC. Higher vacuum limits could not be tested on these 2 units. Surge volumes varied from 17 to 77 μL on the Centurion, 30 to 103 μL on the Whitestar Signature, 67 μL to 163 μL on the Stellaris PC, and 47 to 165 μL on the EVA. Assuming an average phakic eye aqueous volume of 250 μL, these μL values correspond to percent aqueous volume losses of 7% to 31% on the Centurion, 12% to 41% on the Whitestar Signature, 27% to 65% on the Stellaris PC, and 19% to 66% on the EVA. Surge responses increased on all machines with each increment in vacuum limit. The Centurion had the lowest surge volumes across all vacuum limits.

CONCLUSIONS

Occlusion break surge volumes vary considerably across phacoemulsification platforms. Severe chamber shallowing might occur if an occlusion break occurs under high vacuum on some systems.