Digital tonometer may better track IOP after LASIK, study suggests

A new digital tonometry device may be more appropriate than traditional tonometry for monitoring IOP in patients after LASIK, a study by researchers in Greece suggests.

Ophthalmologists Dimitrios S. Siganos, MD, PhD, and colleagues at the Vlemma Eye Institute in Athens measured the IOPs of 118 eyes before undergoing LASIK and at 1 week and 1 month postop using Goldmann applanation tonometry, noncontact air tonometry and the Pascal dynamic contour tonometer (Swiss Microtechnology AG).

According to Swiss Microtechnology, the Pascal tonometer is a third-generation digital tonometer that measures pulsatile IOP directly and continuously after a few seconds in contact with the cornea.

In the study, preoperative central corneal thickness correlated with IOP measurements made using both Goldmann and noncontact tonometry, but not with the Pascal tonometry measurements.

The median reduction in central corneal thickness after LASIK was 78 µm (range –3 µm to –171 µm). Mean IOP measured using Goldmann tonometry decreased by –4.9 ± 2.7 mm Hg at 1 week and –5.4 ± 3 mm Hg at 1 month postop, and similar decreases were seen using noncontact tonometry. These observed changes in IOP were not directly proportional to the postoperative change in central corneal thickness, refractive error or mean keratometric readings.

There was no significant difference between the preoperative and postoperative IOP measurements made using the Pascal tonometer, the authors said.

“The structural corneal changes induced by LASIK appeared to influence [Goldmann tonometry] and [noncontact tonometry] measurements but not [Pascal tonometry] measurements. Therefore, [Pascal tonometry] may be better suited for monitoring IOP in unoperated eyes and in eyes that have had LASIK,” the authors concluded in their abstract.

The study is published in the Journal of Cataract and Refractive Surgery.