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 ORA and GAT one after another. cGAT was calculated according to a correction formula for IOP after LASIK. Central corneal thicknesses and corneal curvature (K value) were also measured. Corneal hysteresis and corneal resistance factor (CRF) were measured by the ORA. 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 ± 2.26 mm Hg, respectively. The mean difference between IOPcc and cGAT was 0.63 ± 1.31 mm Hg (p<0.05). The upper and lower limits of agreement between the IOPcc and cGAT were +3.2 and -1.9 mm Hg. There was a significant correlation between cGAT and CRF; however, no significant correlation could be found between cGAT and corneal hysteresis. 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 in fair agreement with that obtained by IOPcc, which may be helpful for IOP readings in subjects after LASIK. CRF might be a factor that affects accurate IOP readings.
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 ORA and GAT one after another. cGAT was calculated according to a correction formula for IOP after LASIK. Central corneal thicknesses and corneal curvature (K value) were also measured. Corneal hysteresis and corneal resistance factor (CRF) were measured by the ORA. 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 ± 2.26 mm Hg, respectively. The mean difference between IOPcc and cGAT was 0.63 ± 1.31 mm Hg (p<0.05). The upper and lower limits of agreement between the IOPcc and cGAT were +3.2 and -1.9 mm Hg. There was a significant correlation between cGAT and CRF; however, no significant correlation could be found between cGAT and corneal hysteresis. 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 in fair agreement with that obtained by IOPcc, which may be helpful for IOP readings in subjects after LASIK. CRF might be a factor that affects accurate IOP readings.
Authors: Joshua S Hardin; Christopher I Lee; Lydia F Lane; Christian C Hester; R Grant Morshedi Journal: Graefes Arch Clin Exp Ophthalmol Date: 2018-07-23 Impact factor: 3.117