Evaluating Intraocular Pressure After Myopic Photorefractive Keratectomy: A Comparison of Different Tonometers

All devices evaluated in this study showed a significant underestimation in intraocular pressure (IOP) measurement after myopic photorefractive keratectomy (PRK), Goldmann tonometer more than others. Corneal biomechanics indicated a different influence on the different kinds of tonometry.

The aim was to investigate the reliability of Goldmann applanation tonometry (GAT), rebound tonometry (RT), ocular response analyzer (ORA), Corvis ST (CST), and dynamic contour tonometry (DCT) in IOP evaluation after myopic PRK.

One eye of 145 patients who underwent myopic PRK for a refractive defect ranging from -10.25 to -0.50 D (mean -4.69±2.00 D) was included in this retrospective comparative study. A complete eye visit with corneal tomography and IOP measurement with GAT, DCT, ORA, RT, and CST was performed before surgery and at 1, 3, and 6 months follow-up. Values provided by each device were tested and compared at each follow-up. Correlation analyses were run between changes in IOP and the corneal, morphologic and biomechanical parameters were measured after PRK.

GAT, DCT, ORA, RT, and CST showed a significant (P<0.01) underestimation of IOP at 6 months follow-up. GAT showed the greatest underestimation (-14.1%) and stronger correlations with corneal deformation parameter changes, whereas ORA, DCT, and RT appeared to be less conditioned by these variations. At 6 months follow-up DCT, ORA, RT, and CST provided IOP values with nonsignificant differences compared with GAT before PRK.

Each tested tonometer showed a significant IOP underestimation after myopic PRK. As this was most observed with GAT compared with all devices, we suggest DCT, ORA, RT, or CST to evaluate IOP in these patients following surgery.