Rebound Tonometry in Cataract Surgery: Comparison with Goldmann Applanation Tonometry

Abstract

Purpose: to compare the rebound tonometer ICare® (RT) with the Goldmann applanation tonometer (GAT) in cataract surgery and to assess the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements. Design: retrospective, comparative study. Methods: a total of 472 patients underwent IOP measurement using RT (time 0 = RTa). GAT IOP measurement was performed 5 minutes later, followed by a second RT IOP measurement after other 5 minutes (RTa + 10 min = RTb). CCT was obtained by ultrasound pachymetry. In 106 patients IOP was measured by means of RT and GAT before clear corneal cataract surgery (RT1 and GAT1) and at one day postoperatively (RT2 and GAT2). Results: RT IOP values > 5 mmHg were overestimated, while RT IOP values < 15 mmHg were underestimated. Every 100 μm of CCT an increase of 0.97 mmHg and 0.33 mmHg was found for RT and GAT respectively. The difference between RT1 and RT2, GAT1 and GAT2, RT1 and GAT1 was not statistically significant; while the difference between RT2 and GAT2 was statistically significant (p < 0.04). The difference between RTa and RTb was not statistically significant whereas the difference between RTa and GAT and RTb and GAT was statistically significant (p < 0.001). Conclusion: our results showed a good agreement between measurements obtained with RT and GAT in pre and postoperative cataract surgery, although a significant statistically difference was found between RT and GAT measurements performed postoperatively. Moreover, CCT is a parameter to be considered for the IOP measurement, especially for values obtained with RT.