Pascal immune to corneal biomechanics

Intraocular pressure (IOP) measurements with the Pascal dynamic contour tonometer (PDCT) are relatively immune to changes in corneal biomechanics and pachymetry, according to a study published in the January issue of the American Journal of Ophthalmology.

Dr Jay Pepose and colleagues from the Pepose Vision Institute and the Washington University School of Medicine, St Louis, USA, conducted a prospective, non-randomized study to compare the preoperative and postoperative measurements of corneal biomechanical properties and IOP using Goldmann applanation tonometry (GAT), the ocular response analyser (ORA) and the PDCT in eyes undergoing myopic LASIK.

A total of 66 myopic eyes were measured for IOP before and after LASIK using the three devices in a randomized sequence. Metrics of corneal biomechanical properties were also recorded. After LASIK, there was a reduction in mean corneal pachymetry of 90.2 µm and in IOP measurements with GAT (Delta= -1.8±-2.8 mmHg; p<0.01), ORA-Goldmann (Delta= -4.6±-2.8 mmHg; p<0.01) and ORA-corneal compensated (Delta= -2.1±-2.6 mmHg; p<0.05). There was, however, no statistically significant difference between pre- and postoperative IOP measurements taken by PDCT (Delta= -0.5±-2.6 mmHg).

It was concluded that IOP measurements with PDCT are less likely to be affected by changes in corneal biomechanics and pachymetry after LASIK than if they are taken by GAT or ORA.