Comparing Post-Occlusion Surge at Decreasing Intraocular Pressures with Pressure Sensing Handpiece

To compare post-occlusion surge pressure at various intraocular pressures using the Active Sentry handpiece.

This experimental (in vitro chamber) study used the Alcon Centurion platform and Active Sentry handpiece with balanced tips. Quad preset was used with settings: vacuum 500 mmHg, aspiration flow 50 mmHg, and IOPs of 30, 50, and 70 mmHg. A rubber disk was fixed within a sealed chamber fitted with an electric pressure sensor to monitor pressure changes. The phacoemulsification tip was inserted into the water-tight port of the pressure chamber, and the foot pedal was set to position two. The tip was put in contact with the disk to replicate tip occlusion and pulled from the disk to simulate occlusion break. Ten trials were performed at each IOP; pressure changes were recorded continuously.

At 70 mmHg IOP, average post-occlusion surge magnitude was 5.76 mmHg ± 0.54; average surge duration was 0.45 s ± 0.10. At 50 mmHg IOP, surge magnitude was 5.76 mmHg ± 1.15; surge duration surge was 0.52 s ± 0.23. At 30 mmHg IOP, surge magnitude was 10.46 mmHg ± 2.86; surge duration was 1.27 s ± 0.51. There was a statistically significant difference between surge magnitude and duration at 30 vs. 50 mmHg IOP (P < 0.05) and at 30 vs. 70 mmHg IOP (P < 0.05).

When utilizing the Active Sentry handpiece, an increased surge risk was not observed when operative IOP was decreased from 70 mmHg to 50 mmHg. However, our data suggest that surge risk increases when operative IOP is decreased to 30 mmHg. The Active Sentry handpiece at 50 mmHg IOP would not introduce greater surge risk than at 70 mmHg IOP.