Effect of Recipient Corneal Pathology on Pascal Tonometer and Goldmann Tonometer Readings in Eyes after Penetrating Keratoplasty

Abstract

PURPOSE: To assess the influence of recipient corneal pathology on the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) in post-penetrating keratoplasty (PKP) eyes. METHODS: Intraocular pressure (IOP) was measured in 40 post-PKP eyes of 40 patients using PDCT and GAT. The study patients were divided into two groups. Group A included patients who had undergone PKP for ectatic corneal disorders (keratoconus, n=20) and group B included patients who had undergone PKP for other non-ectatic corneal disorders (Fuchs, post-corneal ulcer, post-chemical burn,post-trauma, n=20). Keratometric measurements were obtained in all eyes using Orbscan II (Bausch &Lomb) and central corneal thickness (CCT) was measured using Corneo-Gaze Plus (Sonogaze). RESULTS: In group B, a correlation between PDCT and GAT IOP measurements was observed. In group A, GAT IOP measurements were significantly lower than PDCT measurements (3.7 +/- 1.8 mmHg,p<0.001). Additionally, CCT affected GAT IOP measurements much more than PDCT measurements,while corneal curvature did not significantly affect IOP measurements of any instrument in either group. CONCLUSIONS: In post-PKP eyes, PDCT appears to be less influenced than GAT by CCT and pre-existing recipient corneal pathology. Therefore, PDCT may be better suited for monitoring IOP in post-PKP eyes.