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.

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]

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]

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.

Keratoconus

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

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.

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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

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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Words related to keratoconus

noun abnormal cone-shaped protrusion of the cornea of the eye

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