Astigmatism is a common vision condition impacting how light focuses within the eye, leading to blurred or distorted vision. The shape of the eye’s front surface or internal lens affects how light bends, and any irregularities can result in astigmatism. It can evolve throughout a person’s life.
What is Astigmatism
Astigmatism involves an imperfection in the curvature of the eye’s cornea or lens. Instead of being perfectly spherical, the affected surface is shaped more like an American football or the back of a spoon, with one meridian having a steeper curve than the other. This irregular shape prevents light rays from focusing precisely on the retina, resulting in blurry or distorted vision.
There are two primary types of astigmatism. Corneal astigmatism, the more common form, occurs when the cornea, the clear outer layer at the front of the eye, has an irregular curve. Lenticular astigmatism arises from an uneven shape of the eye’s natural lens located behind the pupil.
How Astigmatism Changes Over a Lifetime
Astigmatism can change across different stages of life, from infancy through older adulthood. Many infants are born with astigmatism, and it is a common finding in early childhood. Many cases decrease or resolve as the eye develops, particularly between one and four years of age.
During adulthood, astigmatism tends to be relatively stable. Minor shifts in prescription can occur, but significant changes are less common in younger and middle adulthood. The eye’s structure generally maintains its shape, leading to a consistent astigmatic profile.
In older adulthood, astigmatism commonly increases or shifts, often becoming “against-the-rule” where the steepest curve is horizontal. This change is frequently linked to alterations in the eye’s lens, such as the development of cataracts. Cataracts, a normal part of aging, can induce or alter existing astigmatism as the lens changes shape and density. Corneal astigmatism, while stable until around age 50, can also show a gradual increase in against-the-rule astigmatism over subsequent decades.
Other Reasons Astigmatism May Shift
Beyond aging, various factors can change astigmatism. Genetics plays a role, with astigmatism often having a hereditary component. If family members have astigmatism, there is an increased likelihood of developing it.
Certain eye diseases or conditions can also cause astigmatism to shift. Keratoconus, a progressive condition where the cornea thins and bulges into a cone shape, can significantly distort vision and lead to irregular astigmatism. Corneal scarring from injury or infection can also alter the cornea’s shape, influencing existing astigmatism or inducing new irregularities.
Eye surgery can impact astigmatism, either by correcting it or, in some cases, inducing or altering it. Cataract surgery can use specialized toric intraocular lenses (IOLs) to correct astigmatism, though incision placement or healing can also lead to changes. Refractive surgeries like LASIK or PRK reshape the cornea to correct astigmatism, though residual astigmatism can sometimes persist or develop due to various factors after the procedure. Direct eye trauma, such as blunt force injuries, can also cause changes to the cornea’s shape, worsening astigmatism.
Addressing Changing Astigmatism
When astigmatism changes, individuals may notice symptoms such as blurred or distorted vision, headaches, eye strain, or difficulty with night vision, including glare or halos around lights. These visual disturbances can impact daily activities and signal a need for professional evaluation. Monitor vision and seek care if changes occur.
Regular eye examinations are important for detecting and monitoring astigmatism. During an exam, an eye care professional can assess the cornea and lens, determining the appropriate prescription for clear vision. Early identification allows for timely management and helps maintain optimal visual function.
Changing astigmatism can be managed through various correction options. Updating prescriptions for eyeglasses or toric lenses is a common approach to improve vision. Surgical options include toric IOLs during cataract surgery, which correct astigmatism simultaneously with cataract removal. Refractive surgeries like LASIK or PRK can also reshape the cornea to correct astigmatism, reducing dependence on corrective eyewear.