Steroid-induced ocular hypertension after photorefractive keratectomy

Abstract

We read with great interest the article by Busool et al.1 about risk factors predicting steroid-induced ocular hypertension after photorefractive keratectomy (PRK). We would like to make some comments because in our opinion, some points that need to be clarified. It is well known that several parameters change after PRK,2,3 making some measurements unreliable.4 Among these, corneal thinning makes Goldmann applanation tonometry measurements unreliable, giving a false decrease in the intraocular pressure (IOP).5 We are a bit concerned about the criteria the authors used to establish the presence of an increase in IOP. The authors established that patients were classified as steroid responders if they had an IOP elevation of at least 25%, to a minimum of 28 mm Hg, while on topical steroid treatment. This was followed by an IOP drop of at least 25% when steroid treatment was discontinued. We believe this led to a clear underestimation of the real increase in IOP. According to the literature, if no changes in IOP are present after refractive surgery, there should be a decrease in the IOP measurements resulting from corneal thinning and flattening. Therefore, if we consider only patients with an IOP increase of more than 28 mm Hg, several patients with an increased IOP will be missed. In the paper, we were not able to find information on the IOP before PRK; however, if some patients presented with a preoperative IOP of 15 mm Hg, which is one of the most frequent findings, an increase of 25% would be far below 28 mm Hg, which in this case would be an increase of almost 100%. Moreover, the drop of 25% does not mean that there is a normalization of the IOP but that rather increased IOP could still be present.