Efficacy of preservative-free tafluprost in patients with normal-tension glaucoma previously treated with latanoprost.

Abstract

Dear editor We read with interest the article entitled “Effects of tafluprost treatment for 3 years in patients with normal-tension glaucoma” by Inoue et al.1 In this study, the authors reported the efficacy of tafluprost in naive patients with normal-tension glaucoma (NTG) over 3 years of follow-up. The intraocular pressure (IOP)-lowering efficacy of tafluprost in NTG has been recently reported by Mizoguchi et al2 and Nakano et al.3 Whereas tafluprost is available in Europe in a preservative-free formulation, the three aforementioned studies1–3 were all carried out in Japan, where tafluprost is on the market as a benzalkonium chloride (BAK)-containing formulation. Recent literature reported BAK-related ocular surface inflammation and epithelial damage,4 which led to the development of preservative-free antiglaucoma drugs. The cytotoxic effect of BAK on conjunctival and corneal epithelium has been claimed to increase ocular penetration of topical drug, enhancing the therapeutic effect.5 As the presence of preservative may play a role in the IOP-lowering effect, we believe it is of interest to report the efficacy of BAK-free formulations in NTG. In a previous study by our group, BAK-free tafluprost showed a comparable efficacy to other prostaglandin analogs, with a safe profile in patients with primary open-angle glaucoma.6 In this letter, we want to report our experience with preservative-free tafluprost in patients with NTG. Herein, we present a retrospective study on 58 eyes of 58 patients (mean age 65.8±9.2 years, range 43–91 years) with NTG previously treated with BAK-preserved latanoprost who were switched to unpreserved tafluprost for ocular surface discomfort. The study was carried out with approval from the Institutional Ethics Committee (San Giuseppe Hospital, MultiMedica) and adhered to the tenets of the Declaration of Helsinki. To be included, patients had to have unilateral or bilateral NTG. Diagnosis of NTG was made on the basis of optic-disk abnormalities and visual-field defects judged by a trained glaucoma specialist to be characteristic of glaucoma with IOP <21 mmHg at any time points of the diurnal IOP curve (8 am, 11 am, 2 pm, 5 pm). All patients were followed in our hospital (San Giuseppe Hospital) from January 2011 to December 2013. Inclusion criteria were: at least 3 months of treatment with BAK-preserved latanoprost followed by at least 3 months of treatment with unpreserved tafluprost; switch to tafluprost due to ocular discomfort; and availability of data from three diurnal IOP curves (untreated, treated with latanoprost, and after switch to tafluprost). Both latanoprost and tafluprost significantly reduced the diurnal mean IOP compared to baseline (12.7±1.7 mmHg versus 14.9±1.9 mmHg, −15%, P<0.001 and 12.2±1.8 mmHg versus 14.9±1.9 mmHg, −18%, P<0.001, respectively) (Figure 1). Conjunctival hyperemia was reported in 17% and 8% of patients and fluorescein corneal staining in 6% and 2% of patients receiving latanoprost and tafluprost, respectively. Figure 1 Intraocular pressure at baseline, with latanoprost, and after switch from latanoprost to tafluprost. The retrospective nature of this study, the absence of a wash-out period, and the short follow-up are all limitations of this report and we are aware that our results need to be confirmed by powered, prospective, randomized clinical trials. However, to the best of our knowledge, this is the first report on the efficacy of BAK-free tafluprost in NTG. In our study, the percentage IOP reduction from untreated baseline for both latanoprost (15%) and tafluprost (18%) was similar to that reported in other studies investigating the efficacy of prostaglandin analogs in NTG and ranging from 16%7 to 19%.8 This study suggests the effectiveness of preservative-free tafluprost in NTG, showing results comparable to those obtained in Japanese patients1–3 using a BAK-preserved formulation.