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.