Use of a calibrated force gauge in clear corneal cataract surgery to quantify point-pressure manipulation

PURPOSE: To develop and evaluate a calibrated force gauge designed to simulate the effect of patient-induced manipulation of the eye with resultant elevation of intraocular pressure (IOP) and use the device to determine the stability of cataract incisions. SETTING: Three private practice study sites. DESIGN: Clinical trials. METHODS: A calibrated force gauge was developed to apply controlled and quantifiable amounts of force to the eye. In study 1, the calibrated force gauge was used to evaluate the change in IOP during application of 1 oz of external force in a group of healthy volunteers. In studies 2 and 3, the calibrated force gauge was used to assess wound leakage of clear corneal incisions that were subjected to stromal hydration or sutures, respectively. RESULTS: In study 1, with the application of 1.00 oz of external force, the mean IOP rose from a baseline of 17.49 mm Hg to 43.44 mm Hg. In study 2 (stromal hydration) using up to 1.00 oz of force, the leak rate was 67% for the main incision. The overall leak rate for study 3 (sutures) using up to 1.00 oz of force was 23.8%. No adverse events or serious adverse events occurred during these studies. CONCLUSIONS: Study 1 confirmed that 1.00 oz of force is a realistic approximation of the amount of force a patient's eye may experience during rubbing. After clear corneal cataract surgery, the application of 1.00 oz of force to the ocular surface for approximately 2 to 3 seconds may simulate the propensity for postoperative wound leak resulting from patient manipulation.