ReviewWhat Causes Keratoconus?Sugar, Joel MD; Macsai, Marian S. MDAuthor Information *Department of Ophthalmology, University of Illinois at Chicago, Chicago, IL †Department of Ophthalmology, University of Chicago, Chicago, IL ‡NorthShore University HealthSystem, Evanston, IL. Reprints: Marian S. Macsai, Division of Ophthalmology, Suite 220, 2050 Pfingsten Rd, Glenview, IL 60026 (e-mail: [email protected]). The authors have no financial disclosures or conflicts of interest to declare. Received January 25, 2011 Accepted August 6, 2011 Cornea: June 2012 - Volume 31 - Issue 6 - p 716-719 doi: 10.1097/ICO.0b013e31823f8c72 Buy Metrics Abstract Purpose: The etiology of keratoconus has been the subject of numerous studies. Here, we review the body of literature that attempts to determine what causes keratoconus. Methods: A review of the published literature was performed to evaluate the possible causes of keratoconus and how the different etiologies may play a role in the development of this disease. Results: Peer-reviewed published papers and recent abstracts concerning the different etiologies of keratoconus were reviewed and discussed. Biochemical, genetic, and environmental factors are reviewed. The role of eye rubbing and atopic disease are explored. Conclusions: We agree with the hypothesis that there is a genetic predisposition that requires a “second hit” or environmental event to elicit progressive disease in keratoconus. Eye rubbing may serve as the “second hit” in some predisposed individuals. Inflammatory mediator studies question if keratoconus is really a noninflammatory thinning disorder of the cornea. Copyright © 2012 Wolters Kluwer Health, Inc. All rights reserved.