Astigmatism is a common imperfection in the eye’s curvature, affecting either the cornea or the lens inside the eye. This irregularity causes light to bend unevenly, resulting in blurred or distorted vision. While often present from birth, vision changes, including shifts in astigmatism, can occur over time. This article explores the reasons behind these changes.
Understanding Astigmatism Changes
Changes in astigmatism are common and a normal part of aging. These changes can involve an increase or decrease in the amount of astigmatism or a shift in its orientation. Minor, gradual fluctuations are generally benign.
However, more significant or rapid changes might indicate an underlying eye health issue. Only an eye care professional can determine the cause through a comprehensive examination. Regular monitoring helps detect such shifts early.
Common Reasons for Astigmatism Shifts
Age-Related Changes
Aging influences eye structures, changing the curvature of the cornea and lens. This can lead to an increase or decrease in astigmatism, often shifting from “with-the-rule” (vertical meridian steepest) to “against-the-rule” (horizontal meridian steepest).
Conditions like cataracts, a clouding of the eye’s natural lens, can also cause astigmatism changes. As the lens thickens and changes shape, it can induce or worsen astigmatism by altering light passage. Keratoconus, another cause, involves the progressive thinning and bulging of the cornea into a cone shape. This leads to myopia and irregular astigmatism.
Eye Health Conditions
Other eye conditions can temporarily or permanently alter astigmatism. Dry eye syndrome, characterized by insufficient or poor-quality tears, can create an uneven tear film on the eye’s surface. This irregularity can temporarily distort how light enters the eye, exacerbating symptoms. Blepharitis, an inflammation of the eyelid margins, can also affect the tear film and corneal surface, contributing to blurred vision and irritation.
Corneal dystrophies, inherited disorders causing cloudy material buildup in the cornea, can lead to irregular astigmatism as the cornea loses clarity or becomes uneven. Systemic diseases, such as diabetes, impact eye health. High blood sugar levels can cause the eye’s lens to swell and change shape, leading to temporary lenticular astigmatism changes.
Lifestyle and Environmental Factors
Temporary changes in astigmatism can be linked to lifestyle and environmental factors. Prolonged eye strain, often associated with extended screen use, can contribute to discomfort and perceived vision changes, though it does not directly cause astigmatism. Certain medications can have ocular side effects that influence vision. Improper contact lens use or a poor lens fit can also temporarily alter corneal shape or cause irritation, leading to blurred vision or irritation.
Post-Surgical Effects
Eye surgeries, such as LASIK, PRK, or cataract surgery, intentionally reshape the cornea or replace the lens to correct vision. While these procedures aim to reduce or eliminate astigmatism, the healing process can lead to residual astigmatism or shifts. Corneal scarring, epithelial remodeling, and wound healing influence the final corneal shape and refractive error. After cataract surgery, incision placement and the type of intraocular lens (IOL) implanted can influence post-operative astigmatism.
When to Seek Professional Guidance
Consult an eye care professional for any vision changes. Certain symptoms require immediate attention, such as sudden vision changes, significant blurriness, or sudden vision loss. Other signs include eye pain, double vision, halos around lights, or frequent headaches.
Regular comprehensive eye exams are important for early detection and monitoring. An eye care professional uses diagnostic tools, such as keratometry and corneal topography, to assess the eye’s curvature and determine the cause. They can then recommend the appropriate course of action, tailored to your condition.
Adapting to Changing Astigmatism
Managing changing astigmatism often involves updating corrective lenses. This typically means new prescription eyeglasses or specialized toric contact lenses, designed with different powers to correct uneven curvature. For some, orthokeratology (Ortho-K) may be an option, using rigid contact lenses worn overnight to temporarily reshape the cornea.
Sometimes, medical or surgical treatments for underlying conditions may be recommended. For instance, cataract surgery can address astigmatism simultaneously with the removal of the clouded lens by implanting a toric intraocular lens. For progressive conditions like keratoconus, corneal cross-linking can strengthen the cornea and help slow or halt disease progression. Consistent monitoring and adherence to recommendations are important for clear vision and eye health.