Astigmatism is a very common and treatable imperfection in the curvature of the eye that causes blurred distance and near vision. It occurs when either the front surface of the eye (cornea) or the lens inside the eye has mismatched curves. Typically the eye has one curve like a round ball. Those with an astigmatism the eye has a surface that is egg-shaped. This shape prevents light from focusing properly on the retina and causes blurred vision at all distances.
Astigmatism is often present at birth and may occur in combination with nearsightedness or farsightedness. Often the astigmatism is not pronounced enough to require corrective treatment. When it is, treatment options are corrective lenses or surgery.
Causes & risk factors
Hereditary and is usually present from birth.
May develop following an eye injury or eye surgery.
It can occur due to a relatively rare condition called keratoconus in which the cornea becomes progressively thinner and cone-shaped.
It can decrease or increase over time.
Blurred vision at any distance.
Eyeglasses. People with astigmatism primarily choose eyeglasses to improve their vision. The eyeglasses contain a special cylindrical lens prescription that compensates for astigmatism. This provides additional power in specific parts of the lens.
Contact lenses. Some people will have better vision with contact lenses rather than eyeglasses. Contact lenses may provide a clearer vision and a wider field of view.
Orthokeratology. Orthokeratology involves the fitting of a series of rigid contact lenses to reshape the cornea. The patient wears contact lenses for limited periods of time.
Laser and other refractive surgery procedures. Astigmatism can also be corrected by reshaping the cornea through LASIK or photorefractive keratectomy. PRK removes tissue from the superficial and inner layers of the cornea. LASIK removes tissue only from the inner layer of the cornea.