Also found in: Dictionary, Thesaurus, Acronyms, Encyclopedia, Wikipedia.


conical protrusion of the central part of the cornea, resulting in an irregular astigmatism.
Keratoconus. From Dorland's, 2000.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(ker'ă-tō-kō'nŭs), [MIM*148300]
A conic protrusion of the cornea caused by thinning of the stroma; usually bilateral.
See also: Fleischer ring, Munson sign.
Synonym(s): conic cornea
[kerato- + G. kōnos, cone]
Farlex Partner Medical Dictionary © Farlex 2012


A conic protrusion of the cornea caused by thinning of the stroma; usually bilateral.
See also: Fleischer ring, Munson sign
Synonym(s): conic cornea.
[kerato- + G. kōnos, cone]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A growth disorder (dystrophy) of the CORNEA causing central peaking or conicity and affecting vision. The main disability is from image distortion. Keratoconus is a familial condition that usually starts in adolescence, affecting girls more than boys. Spectacles may help at first, the progressive distortion usually calls for correction with hard contact lenses. Corneal grafting is often eventually required but the results are usually good.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


An eye condition in which the cornea bulges outward, interfering with normal vision. Usually both eyes are affected.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

keratoconus (KC)

A developmental anomaly in which the central portion of the cornea becomes thinner and bulges forward in a cone-shaped fashion. Two types of cones are commonly described: a round cone and an oval (or sagging) cone. It usually appears around puberty, is bilateral, although one eye may be involved long before the other. Other corneal signs may be Vogt's striae, Fleischer's ring, scarring and corneal hydrops, as well as myopia and irregular astigmatism. The condition may be associated with osteogenesis imperfecta, ectopia lentis, aniridia, retinitis pigmentosa, Down's syndrome, Ehlers-Danlos syndrome, Marfan's syndrome. The main symptom is a loss of visual acuity due to irregular astigmatism and myopia. Correction is usually best achieved with contact lenses, especially rigid gas permeable, but if these cannot be worn or the condition is very severe, a corneal transplant is carried out (Fig. K1). Syn. conical cornea. See central corneal clouding; pellucid marginal degeneration; corneal ectasia; acute hydrops; keratoscope; combination lens; piggyback lens; lenticonus; blue sclera; Munson's sign; Rizzuti's sign; stria; corneal topography.
Fig. K1 Schematic diagram of a keratoconus corneaenlarge picture
Fig. K1 Schematic diagram of a keratoconus cornea

Table K1 Differential diagnosis between keratoconus and related thinning disorders. (Adapted from Krachmer JH, Feder RS, Belin MW. Surv Ophthalmol 1984; 28:293-322)
keratoconuspellucid marginal degenerationkeratoglobusposterior keratoconus
frequencymost commonless commonrareleast common
lateralityusually bilateralbilateralbilateralusually unilateral
age of onsetpuberty/early adulthoodAge 20 to 40susually at birthbirth
corneal thinningcentral or paracentralinferior crescent-shaped band 1-2 mm widegeneralized and slightly more in peripheryparacentral posterior excavation
protrusionapicalabove band of thinninggeneralizednone
iron line
(Fleischer's ring)
scarringcommononly after hydropsrarecommon
progressionyesyesusually nono
induced astigmatismirregularhigh, irregular and varies with locationnonevery slight effect
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann

Patient discussion about keratoconus

Q. Has anyone had experience with a corneal transplant because of keratoconus?

A. my uncle had to do a transplant- it took 5 weeks until he could see anything , another year to get his vision straightened up. but now he is fine! i know that he looked for information in the "National Keratoconus Foundation". they were very helpful (and nice!), they have a website with information on all forms of treatment:

good luck :)

More discussions about keratoconus
This content is provided by iMedix and is subject to iMedix Terms. The Questions and Answers are not endorsed or recommended and are made available by patients, not doctors.
References in periodicals archive ?
Zumhagen, "Changes in corneal transparency after crosslinking for progressive keratoconus: long-term follow-up," Journal of Refractive Surgery, vol.
In the cases of unilateral keratoconus, we chose to collect the fluid from the diseased eye.
This single-station and single surgeon prospective randomized study comprised of male and female patients between 16 to 35 years of age, included by non-probability consecutive sampling suffering from significant keratoconus with k-readings greater than 47D and central corneal thickness more than 400um.
In contrast, the corneas of keratoconus patients showed significant increases in staining, both in the epithelium and in the stroma; at the level of the epithelium, a homogeneous overexpression in keratoconus was observed, while the stroma showed a particularly intense overexpression, predominantly in the subepithelial region (Figure 2, B).
Inclusion criteria for the calculations for this study were no ocular surgery, no other ocular diseases than keratoconus, complete data of the complete ophthalmological examination, including tomography measurements using Scheimpflug imaging (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany), Placido disk video topography (TMS-5, Tomey Corporation, Nagoya, Japan), and biomechanical examination using the Ocular Response Analyzer (ORA).
Keratoconus KC is a condition of the eye which results in liberal thinning of the cornea.
(2.) Gomes JA, Tan D, Rapuano CJ, Belin MW, Ambrosio R Jr, Guell JL, Malecaze F, Nishida K, Sangwan VS; Group of Panelists for the Global Delphi Panel of Keratoconus and Ectatic Diseases.
"The discovery of additional genetic markers will help us to reliably predict which people are at a higher risk of keratoconus in the future, which is very exciting."
Slit-lamp biomicroscopic findings like Vogt's striae, Fleischer's ring, stromal thinning and stromal scarring and findings consistent with diagnosis of keratoconus were recorded for each subject.
Brian Boxer Wachler, on a foundation called Giving Vision - to award grants to needy Keratoconus patients for travel expenses and, in several cases, the entire cost of the sight-saving procedure.
The differences in the demographic characteristics and the prevalence of keratoconus between those subjects with and without autoimmune disease were analyzed by means of the chi-square test.
The most common corneal ectatic disorder and a leading indicator for corneal transplantation in developed countries is keratoconus (KC) [2, 3].