Goldmann Applanation Tonometer Versus Ocular Response Analyzer for Measuring Intraocular Pressure After Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE: To evaluate agreement between IOP measured using the ocular response analyzer (ORA) versus using the Goldmann applanation tonometer (GAT) in patients treated by Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This prospective, case-control study comprised 38 normal eyes and 37 post-DSAEK eyes. IOP was measured using the GAT (IOPGAT). The ORA was used to measure corneal biomechanics and cornea-compensated IOP (IOPCC). Corneal hysteresis (CH), corneal resistance factor, and IOP measurements of the 2 groups were compared. Intertonometer agreement was evaluated in each study group using Bland-Altman plots and 95% limits of agreement. Univariate analysis was used to evaluate the effect of independent factors on the difference between the 2 IOP readings (ΔIOP). RESULTS: The IOPCC and IOPGAT readings showed no significant intergroup differences. IOPCC was significantly higher than IOPGAT, with a mean difference of 3.0 ± 3.3 mm Hg in the normal group (P < 0.001) and 4.5 ± 3.1 mm Hg in the DSAEK group (P < 0.001). The 95% limits of agreement for the IOPCC and IOPGAT was between -3.4 and 9.5 mm Hg and between -1.6 and 10.6 mm Hg in the normal and DSAEK groups, respectively. CH (r = -0.57, P < 0.001) and donor thickness (r = 0.81, P = 0.04) were identified as the main predictors of ΔIOP after DSAEK. ΔIOP did not vary significantly with the central corneal thickness or corneal resistance factor. CONCLUSIONS: The IOPGAT and IOPCC were significantly different, which indicates that the GAT and ORA cannot be used interchangeably for measuring IOP after DSAEK. The difference between these 2 measurements was primarily affected by the variations in CH and donor thickness.