Clinical comparison of ocular blood flow tonometer, tonopen, and Goldmann applanation tonometer for measuring intraocular pressure in postkeratoplasty eyes

Purpose. Intraocular pressure (IOP) measurements vary with different tonome ters in irregular corneas. The purpose of our study was to determine the co mparability of the ocular blood flow tonometer (OBF) and Tonopen with the G oldmann applanation tonometer (GAT) in measuring IOP in post-keratoplasty e yes. Methods. The IOP was measured using the OBF tonometer, GAT, and Tonope n in 69 post-keratoplasty eyes by two observers. The same instruments were used, and the sequence of measurements was randomized. Pachymetry to measur e corneal thickness was done in all patients. Results. Interobserver variat ion for IOP measured with GAT was statistically significant (p = 0.039). Tw o-way analysis of variance (ANOVA), however, did not demonstrate any statis tical difference between measurements with the three tonometers and two obs ervers. Corneal thickness did not appear to have an effect on measurements with any of the tonometers. Conclusion. There was no significant difference in the overall accuracy of the OBF tonometer over the Tonopen versus the G AT. The OBF tonometer can be a useful alternative in measuring IOP in postk eratoplasty eyes.