Citation: Filippelli, M.; Campagna, G.; Ciampa, N.; Fioretto, G.; Giannini, R.; Marino, P.F.; dell’Omo, R.; Costagliola, C. Ocular Tolerability of Bimatoprost 0.1 mg/mL Preservative- Free versus Bimatoprost 0.1 mg/mL with Benzalkonium Chloride or Bimatoprost 0.3 mg/mL Preservative- Free in Patients with Primary Open-Angle Glaucoma. J. Clin. Med. 2022, 11, 3518. https://doi.org/ 10.3390/jcm11123518 Academic Editor: Jose Javier Garcia-Medina Received: 11 April 2022 Accepted: 17 June 2022 Published: 19 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Journal of Clinical Medicine Article Ocular Tolerability of Bimatoprost 0.1 mg/mL Preservative-Free versus Bimatoprost 0.1 mg/mL with Benzalkonium Chloride or Bimatoprost 0.3 mg/mL Preservative-Free in Patients with Primary Open-Angle Glaucoma Mariaelena Filippelli 1, * ,† , Giuseppe Campagna 2,† , Nicola Ciampa 3 , Gaetano Fioretto 3 , Roberta Giannini 4 , Pier Franco Marino 3 , Roberto dell’Omo 1 and Ciro Costagliola 1,3 1 Department of Medicine and Health Sciences, “V. Tiberio”, University of Molise, 86100 Campobasso, Italy; roberto.dellomo@unimol.it (R.d.); ciro.costagliola@unimol.it (C.C.) 2 Department of Medical-Surgical Sciences and Translational Medicine, University of Rome “Sapienza”, 00185 Rome, Italy; gius.campagna@gmail.com 3 Department of Neurosciences, Reproductive Sciences and Dentistry, University of Naples Federico II, 80138 Naples, Italy; nicolaciampa3@gmail.com (N.C.); fioretto.gaetano@gmail.com (G.F.); alpapini@tiscali.it (P.F.M.) 4 Department of Ophthalmology, San Camillo Hospital, 00152 Rome, Italy; robertagiannini1@gmail.com * Correspondence: oftelena@gmail.com † These authors contributed equally to this work. Abstract: This study aimed to evaluate whether the therapeutic switch from a formulation of Bimato- prost 0.1 mg/mL with benzalkonium chloride (BAK) or Bimatoprost 0.3 mg/mL preservative-free to a formulation of Bimatoprost 0.1 mg/mL preservative-free could improve eye surface conditions in patients with glaucoma; intraocular pressure (IOP) was also evaluated. All patients meeting the inclusion criteria were eligible for the therapeutic switch to Bimatoprost 0.1 mg/mL preservative- free. At each check visit, enrolled patients underwent a break-up time (BUT) test, an ocular surface disease index (OSDI) test, and a three-point tonometric curve. A total of 40 patients were enrolled (23 were in therapy with Bimatoprost 0.1 mg/mL with BAK and 17 with Bimatoprost 0.3 mg/mL preservative-free). Significant differences of OSDI and BUT between Bimatoprost 0.1 mg/mL with BAK at baseline vs. Bimatoprost 0.1 mg/mL preservative-free at 14 and 28 days (p < 0.0001 and p = 0.0003, respectively) were recorded. Similarly, significant differences of OSDI and BUT between Bimatoprost 0.3 mg/mL preservative-free at baseline vs. Bimatoprost 0.1 mg/mL preservative-free at 14 and 28 days (p < 0.0001 for both) were found. Bimatoprost 0.1 mg/mL preservative-free has a better tolerability profile associated with non-therapeutical inferiority in the control of IOP compared to the other Bimatoprost formulations. Keywords: primary open-angle glaucoma; bimatoprost; benzalkonium chloride; break-up time (BUT) test; ocular surface disease index (OSDI); intraocular pressure (IOP) 1. Introduction Glaucoma is defined as a group of irreversible, progressive optic neuropathies that can lead to severe visual field loss and blindness [1]. Primary open-angle glaucoma (POAG) is the most widespread type of glaucoma in European and African populations [2]. It is estimated that 57.5 million people worldwide suffer from POAG and it is expected that this number will reach 111.8 million by 2040 [3]. The reduction in light scattered by the retinal nerve fiber layer (RFNL) near the optic nerve head is assumed to be an early indicator of axonal degeneration and a sensitive way to identify glaucomatous damage [4,5]. Several risk factors for glaucoma onset are known, such as age, gender, family history of glaucoma, genetics, race (no white ethnicity), myopia, pseudoexfoliation, J. Clin. Med. 2022, 11, 3518. https://doi.org/10.3390/jcm11123518 https://www.mdpi.com/journal/jcm