Astigmatism

astigmatism

type of disease, signs den symptoms

Subclass of	astigmatism
Health specialty	ophthalmology
Possible treatment	cylindrical lens
ICD-9-CM	367.20, 367.2
ICPC 2 ID	F91

Astigmatism be a type of refractive error secof rotational asymmetry insyd de eye ein refractive power. De lens den cornea of an eye widout astigmatism nearly be spherical, plus a single radius of curvature per, den any refractive errors present fi be corrected plus simple glasses. Insyd an eye plus astigmatism, either de lens anaa de cornea slightly be egg-shaped, plus higher curvature insyd one direction dan de oda. Dis dey give distorted anaa blurred vision at any distance den dey require corrective lenses wey apply different optical powers at different rotational angles. Astigmatism fi lead to symptoms wey include eyestrain, headaches, den trouble driving at night. Often e be present at birth, buh e fi change anaa develop later insyd life, den so fi affect people of all ages. If e occur insyd early life wey dem lef am untreated, e fi result insyd amblyopia.

De cause of astigmatism be unclear, although e be believed to be partly genetic. De underlying mechanism dey involve an irregular curvature of de cornea den protective reaction changes insyd de lens of de eye, dem call lens astigmatism, wey get de same mechanism as spasm of accommodation. Diagnosis both be objective (by an eye examination dem call autorefractor keratometry, wich dey allow examination of de lenticular den corneal components of astigmatism) den subjective (by refraction).

Three treatment options be available: eyeglasses, contact lenses, den surgery. Glasses be de simplest. Contact lenses fi provide a wider field of vision den fewer artifacts dan even double aspheric eyeglass lenses. Refractive surgery dey aim to permanently change de shape of de eye den thereby cure astigmatism.

Insyd Europe den Asia, astigmatism dey affect between 30% den 60% of adults. Na e be first reported by Thomas Young insyd 1801.