Real-Time Dynamic Intraocular Pressure Fluctuations During Microcoaxial Phacoemulsification Using Different Aspiration Flow Rates and Their Impact on Early Postoperative Outcomes: A Randomized Clinical Trial

PURPOSE: To compare the impact of varying fluidic parameters on intraoperative intraocular pressure (IOP) fluctuations and postoperative outcomes. METHODS: Prospective randomized study of 80 eyes undergoing cataract surgery that were randomly assigned to low (aspiration flow rate: 20 cc/min; bottle height: 90 cm; vacuum: 400 mm Hg) and high (aspiration flow rate: 40 cc/min; bottle height: 110 cm; vacuum: 400 mm Hg) fluidic parameter groups. Real-time dynamic intraoperative IOP was measured during nuclear fragment removal. Mean maximum and minimum IOP and percentage reduction in IOP from maximum were compared between groups. Postoperatively, the rate of change in central corneal thickness and anterior chamber inflammation at days 1 and 7, endothelial cell density at 3 months, and corneal clarity on day 1 were compared. RESULTS: Minimum IOP in the low and high parameters groups was 35 ± 4.0 and 34.5 ± 6.8 mm Hg, respectively. Maximum IOP in the low and high parameters groups was 69 ± 3.0 and 85 ± 1.2 mm Hg, respectively ( P < .002). Mean percent reduction from maximum was 59% in the high parameters group compared to 41% in the low parameters group, with the difference being statistically significant ( P < .002). Rate of change in central corneal thickness was greater in the high parameters group at postoperative days 1 and 7 ( P < .001). Anterior chamber inflammation and corneal clarity on the first postoperative day were significantly better in the low parameters group. CONCLUSIONS: Higher aspiration flow rate and bottle heights are associated with high intraoperative IOPs of up to 85 mm Hg. Prolonged elevated IOP during cataract surgery was found to have more anterior segment inflammation and more edematous corneas. [ J Refract Surg. 2014;30(8):534–540.]