| PURPOSE To evaluate the agreement between intraocular pressure (IOP) readings measured by the Ocular Response Analyzer (ORA) and corrected Goldmann applanation tonometry (cGAT), derived from the "gold standard" for the clinical measurement of IOP, in eyes of subjects who have undergone laser in situ keratomileusis (LASIK). The effects of corneal biomechanical properties on IOP were also evaluated.
METHODS This was a retrospective cross-sectional study. The IOP of 148 eyes of 148 patients who have undergone LASIK was measured by the Ocular Response Analyzer (ORA) and Goldmann applanation tonometry (GAT) one after another. Corrected-Goldmann applanation tonometry (cGAT) was calculated according to a correction formula for IOP after LASIK. Central corneal thicknesses (CCT) and corneal curvature (k-value) were also measured. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the ORA as well.
RESULTS For the postoperative subjects, whose ages ranged from 18 to 37 years, the average IOP-readings for GAT, cGAT, IOPg, IOPcc were 10.09 ± 2.43, 13.34 ± 2.52, 9.79 + 2.52, 13.91 ± 2.26mm Hg, respectively. The mean difference between IOPcc and cGAT was 0.63±1.31mm Hg (p<0.05). The upper and lower limits of agreement between the IOPcc and cGAT were +3.2mmHg and -1.9mmHg.There was a significant correlation between cGAT and CRF, however no significant correlation could be found between cGAT and CH.
CONCLUSIONS After being corrected for central corneal thinkness, curvature of the corneal anterior surface and reduced biomechanical bending strength of the cornea, the IOP reading obtained by GAT is somewhat in agreement with that obtained by IOPcc, which may be helpful for IOP readings in subjects following LASIK. CRF might be a factor that affects accurate IOP readings. | 
