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Laura L Wayman, MD
Section Editor
Jonathan Trobe, MD
Deputy Editor
Howard Libman, MD, FACP


Keratoconus is a noninflammatory disorder of the cornea of unknown etiology. It is characterized by progressive thinning and cone-shaped protrusion of the cornea leading to visual impairment (picture 1). Patients may present with blurry vision or a sudden decrease in visual acuity. Corrective lenses may be difficult to fit and require frequent changes due to progressive myopia and irregular astigmatism. Visual impairment is initially managed with corrective lenses but may require surgical correction as the disease progresses.


Patients present at puberty or early adulthood. There are a wide range of prevalences reported in the general population, ranging from 50 to 230 per 100,000 [1-3]. There is no difference in incidence and prevalence between genders [1-5]. Some evidence suggests a higher incidence in Asians from the Indian subcontinent [6,7]. Another study did not support the association between Asians and keratoconus. However, the study did find that blacks and Latinos have approximately 50 percent higher odds of having keratoconus when compared with whites [8].


Systemic disorders – Several studies have linked keratoconus to systemic disorders including Down syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta [8,9]. None have been able to prove a direct cause-and-effect relationship.

Environment – Atopic disease, asthma, and hay fever have been associated with keratoconus; however, not all studies have found an association [3,9].

Eye-rubbing – Reports based on clinical observation have implicated eye rubbing as a risk factor for keratoconus [9].

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Literature review current through: Nov 2017. | This topic last updated: May 13, 2016.
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  1. Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol 1984; 28:293.
  2. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study of keratoconus. Am J Ophthalmol 1986; 101:267.
  3. Rabinowitz YS. Keratoconus. Surv Ophthalmol 1998; 42:297.
  4. Vazirani J, Basu S. Keratoconus: current perspectives. Clin Ophthalmol 2013; 7:2019.
  5. Jhanji V, Sharma N, Vajpayee RB. Management of keratoconus: current scenario. Br J Ophthalmol 2011; 95:1044.
  6. Georgiou T, Funnell CL, Cassels-Brown A, O'Conor R. Influence of ethnic origin on the incidence of keratoconus and associated atopic disease in Asians and white patients. Eye (Lond) 2004; 18:379.
  7. Pearson AR, Soneji B, Sarvananthan N, Sandford-Smith JH. Does ethnic origin influence the incidence or severity of keratoconus? Eye (Lond) 2000; 14 ( Pt 4):625.
  8. Woodward MA, Blachley TS, Stein JD. The Association Between Sociodemographic Factors, Common Systemic Diseases, and Keratoconus: An Analysis of a Nationwide Heath Care Claims Database. Ophthalmology 2016; 123:457.
  9. Sugar J, Macsai MS. What causes keratoconus? Cornea 2012; 31:716.
  10. Hartstein J. Keratoconus that developed in patients wearing corneal contact lenses. Report of four cases. Arch Ophthalmol 1968; 80:345.
  11. Gasset AR, Houde WL, Garcia-Bengochea M. Hard contact lens wear as an environmental risk in keratoconus. Am J Ophthalmol 1978; 85:339.
  12. Goldring MB, Krane SM. Modulation by recombinant interleukin 1 of synthesis of types I and III collagens and associated procollagen mRNA levels in cultured human cells. J Biol Chem 1987; 262:16724.
  13. Sawaguchi S, Yue BY, Chang I, et al. Proteoglycan molecules in keratoconus corneas. Invest Ophthalmol Vis Sci 1991; 32:1846.
  14. Fan Gaskin JC, Patel DV, McGhee CN. Acute corneal hydrops in keratoconus - new perspectives. Am J Ophthalmol 2014; 157:921.
  15. Fernández Pérez J, Valero Marcos A, Martínez Peña FJ. Early diagnosis of keratoconus: what difference is it making? Br J Ophthalmol 2014; 98:1465.
  16. Wagner H, Barr JT, Zadnik K. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date. Cont Lens Anterior Eye 2007; 30:223.
  17. Rabinowitz YS. Videokeratographic indices to aid in screening for keratoconus. J Refract Surg 1995; 11:371.
  18. American Academy of Ophthalmology. 2007-2008 Basic and Clinical Science Course Section 8: External Disease and Cornea, Sutphin JE (Ed), 2007. p.329.
  19. Smiddy WE, Hamburg TR, Kracher GP, Stark WJ. Keratoconus. Contact lens or keratoplasty? Ophthalmology 1988; 95:487.
  20. Colin J, Cochener B, Savary G, Malet F. Correcting keratoconus with intracorneal rings. J Cataract Refract Surg 2000; 26:1117.
  21. Tu KL, Sebastian RT, Owen M, et al. Quantification of the surgically induced refractive effect of intrastromal corneal ring segments in keratoconus with standardized incision site and segment size. J Cataract Refract Surg 2011; 37:1865.
  22. Moodaley L, Buckley RJ, Woodward EG. Surgery to improve contact lens wear in keratoconus. CLAO J 1991; 17:129.
  23. Moodaley L, Liu C, Woodward EG, et al. Excimer laser superficial keratectomy for proud nebulae in keratoconus. Br J Ophthalmol 1994; 78:454.
  24. Gordon MO, Steger-May K, Szczotka-Flynn L, et al. Baseline factors predictive of incident penetrating keratoplasty in keratoconus. Am J Ophthalmol 2006; 142:923.
  25. Keane M, Coster D, Ziaei M, Williams K. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for treating keratoconus. Cochrane Database Syst Rev 2014; :CD009700.
  26. Sharif KW, Casey TA. Penetrating keratoplasty for keratoconus: complications and long-term success. Br J Ophthalmol 1991; 75:142.
  27. Price FW Jr, Whitson WE, Marks RG. Graft survival in four common groups of patients undergoing penetrating keratoplasty. Ophthalmology 1991; 98:322.
  28. Kirkness CM, Ficker LA, Steele AD, Rice NS. The success of penetrating keratoplasty for keratoconus. Eye (Lond) 1990; 4 ( Pt 5):673.
  29. Kasbekar SA, Jones MN, Ahmad S, et al. Corneal transplant surgery for keratoconus and the effect of surgeon experience on deep anterior lamellar keratoplasty outcomes. Am J Ophthalmol 2014; 158:1239.
  30. Lockington D, Fan Gaskin JC, McGhee CN, Patel DV. A prospective study of acute corneal hydrops by in vivo confocal microscopy in a New Zealand population with keratoconus. Br J Ophthalmol 2014; 98:1296.
  31. http://avedro.com/press-releases/avedro-receives-fda-approval/ (Accessed on April 26, 2016).
  32. Koller T, Pajic B, Vinciguerra P, Seiler T. Flattening of the cornea after collagen crosslinking for keratoconus. J Cataract Refract Surg 2011; 37:1488.
  33. O'Brart DP, Patel P, Lascaratos G, et al. Corneal Cross-linking to Halt the Progression of Keratoconus and Corneal Ectasia: Seven-Year Follow-up. Am J Ophthalmol 2015; 160:1154.
  34. Sykakis E, Karim R, Evans JR, et al. Corneal collagen cross-linking for treating keratoconus. Cochrane Database Syst Rev 2015; :CD010621.
  35. Iovieno A, Légaré ME, Rootman DB, et al. Intracorneal Ring Segments Implantation Followed By Same-day Photorefractive Keratectomy and Corneal Collagen Cross-linking in Keratoconus. J Refract Surg 2011; 27:915.