Best tools for measuring IOP in KC patients

The Pascal dynamic contour tonometer (DCT) and Reichert ocular response analyzer (ORA) are the best tools for measuring corneal-compensated intraocular pressure (IOPcc) in patients with keratoconus (KC), according to study results published in the British Journal of Ophthalmology, December.

Susan P. Mollan of Birmingham and Midland Eye Centre, Birmingham, UK and colleagues conducted a prospective study assessing the accuracy of IOP measurement in eyes of normal and KC subjects when measured with a variety of different instruments. Central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) were also measured.

The researchers found statistically significant differences between the IOP values when measured with the different instruments. CCT, CH and CRF were significantly lower in the KC group, and overall, eyes with thicker corneas registered higher IOP measurements than thinner corneas. The Goldman applanation tonometer (GAT) gave IOP values that were statistically significantly lower than the value as measured with any other instrument, including DCT, ORA and the TonoPen XL tonometer.

Thus the team concluded that IOPcc values were less likely to be compromised when measured with DCT or ORA, and that CH and CRT had more impact than CCT on IOP measurements.