Commentary on “Intraocular Pressure After Refractive Surgery”
We appreciate Dr De Bernardo’s and Dr Rosas’s interest in our paper, and we share their concerns on the evident limitations of standard tonometry devices such as Goldmann applanation tonometer (GAT) when measuring intraocular pressure (IOP) in operated corneas.
The validity of the IOP measurements using GAT after corneal refractive surgeries has been questioned, because its accuracy depends on corneal properties that necessarily change after those procedures. Consistent with the report by Rosa et al1 for PRK surgery, we found that Schiotz tonometry (ST) seems to be more accurate in measuring IOP also in patients who had undergone LASIK, compared with the Goldmann technique. Unfortunately we were not aware of this interesting article, as it was not found after a comprehensive review of the literature when searching in PubMed.1 We also agree with the authors in that different corneal refractive procedures make differences in the measurements obtained; in this sense, the change in corneal biomechanical behavior induced by LASIK may be not only due to the reduced corneal thickness but especially due to the flap creation.2
Besides that, we found that although modern tonometers such as the dynamic contour tonometer have been developed to overcome some of these GAT limitations, an old-fashioned instrument as it is, the ST presents a close agreement with dynamic contour tonometer in the IOP measurements, both in LASIK and nonoperated eyes, but, in addition, ST seems to be less affected by previous LASIK.