AS meaning in Medical ?

Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at night. Astigmatism often occurs at birth and can change or develop later in life. If it occurs in early life and is left untreated, it can result in amblyopia.

The cause of astigmatism is unclear, however it is believed to be partly related to genetic factors. The underlying mechanism involves an irregular curvature of the cornea or abnormalities in the lens of the eye. Diagnosis is by an eye examination, through objective and subjective refraction.

Three treatment options are available: glasses, contact lenses, and surgery. Glasses are the simplest. Contact lenses can provide a wider field of vision. Refractive surgery permanently changes the shape of the eye.

In Europe and Asia, astigmatism affects between 30 and 60% of adults. People of all ages can be affected by astigmatism. Astigmatism was first reported by Thomas Young in 1801.