keratoconus

keratoconus

 [ker″ah-to-ko´nus]

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·a·to·co·nus

(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

ker·a·to·co·nus

(ker'ă-tō-kō'nŭs)

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

keratoconus

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

Keratoconus

An eye condition in which the cornea bulges outward, interfering with normal vision. Usually both eyes are affected.

Mentioned in: Corneal Transplantation

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 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)
		keratoconus		pellucid marginal degeneration		keratoglobus		posterior keratoconus
frequency		most common		less common		rare		least common
laterality		usually bilateral		bilateral		bilateral		usually unilateral
age of onset		puberty/early adulthood		Age 20 to 40s		usually at birth		birth
corneal thinning		central or paracentral		inferior crescent-shaped band 1-2 mm wide		generalized and slightly more in periphery		paracentral posterior excavation
protrusion		apical		above band of thinning		generalized		none
iron line (Fleischer's ring)		common		rare		none		occasional
scarring		common		only after hydrops		rare		common
progression		yes		yes		usually no		no
induced astigmatism		irregular		high, irregular and varies with location		none		very 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:
http://www.nkcf.org/

good luck :)

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