Basic InvestigationRole of Thyroxine in the Development of KeratoconusThanos, Solon MD, PhD; Oellers, Patrick MD, PhD; Meyer zu Hörste, Melissa MD, PhD; Prokosch, Verena MD, PhD; Schlatt, Stefan MD, PhD; Seitz, Berthold MD, PhD; Gatzioufas, Zisis MD, PhDAuthor Information *Institute of Experimental Ophthalmology, School of Medicine, University of Münster, Münster, Germany; †Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA; ‡Institute of Regenerative Medicine, University of Münster, Münster, Germany; and §Department of Ophthalmology, Saarland University Medical Center UKS, Homburg, Germany. Reprints: Zisis Gatzioufas, MD, PhD, Department of Ophthalmology, University of Saarland, Kirrberger Strasse 1, Homburg 66424, Germany (e-mail: email@example.com). Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.corneajrnl.com). Received January 07, 2016 Received in revised form June 25, 2016 Accepted July 01, 2016 Cornea: October 2016 - Volume 35 - Issue 10 - p 1338-1346 doi: 10.1097/ICO.0000000000000988 Buy SDC Metrics Abstract Purpose: Keratoconus (KC) is a corneal ectasia whose pathophysiology is still mostly unknown. We investigated whether thyroid gland dysfunction (TGD) is associated with the development of KC. Methods: We first conducted an epidemiological study, examining the prevalence of TGD among patients with KC. Then, we compared tear thyroxine (T4) in TGD and immunohistochemical staining of its receptors (T4Rs) between patients with KC and controls. The significance of T4 for corneal metabolism was studied in organotypic tissue cultures from monkey corneas. Results: We found that TGD prevalence among patients with KC is 13.6%, which is higher than its prevalence in the general population (about 2%). Tear T4 was higher in KC, and keratocyte T4Rs were elevated in KC compared with controls. Furthermore, core proteins such as collagen and cytokeratins were equally altered both in KC and in the cultured corneas substituted with T4. Conclusions: Our data implicate a crucial role of T4 in KC pathophysiology, which is most likely mediated by T4Rs. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.