What Causes Astigmatism in the Eyes?
Mar 20, 2022
Source: Cainiu Health
Dr. Cui Xin
Introduction
I. Changes in astigmatism during myopia: When both eyes look inward and downward simultaneously, the eyeballs rotate, thereby altering the axis of astigmatism.
II. Visual fatigue symptoms: These are typically associated with age and occupational demands—older individuals and those who spend prolonged periods writing at a desk are especially prone.
III. Effects caused by spectacle lenses: These include uneven image magnification, lens axis displacement, and surface irregularities of the lens.
Astigmatism is a type of refractive error, commonly associated with irregular curvature of the cornea. Due to irregular curvatures on the surface of either the cornea or the lens, incoming light rays are scattered and fail to converge at a single focal point on the retina, resulting in blurred or distorted vision. So, what causes astigmatism? Below, we address this question.
What Causes Astigmatism?
Astigmatism—also referred to as “irregular refraction”—arises primarily from an abnormal curvature of the cornea. It frequently occurs in children and adolescents. Several factors may contribute to its development:
1. Changes in astigmatism associated with myopia: When viewing objects downward and inward (e.g., during near work), both eyes undergo rotational movement, altering the axis of astigmatism. Therefore, when prescribing corrective lenses, clinicians consider the patient’s age, depth of focus, and relative accommodative ability to select appropriate distance or near-vision lenses.
2. Visual fatigue symptoms: These are often related to age and occupational demands. Older individuals who spend prolonged periods writing or reading at a desk may develop mild-to-moderate astigmatism. If measured values fall below normal thresholds, optical correction is recommended.
3. Effects of eyeglass lenses: Factors such as unequal image magnification, lens axis misalignment, and surface irregularities of the lens can induce or exacerbate astigmatism. Additionally, frame size may affect peripheral optics and thereby contribute to astigmatic errors.
Therefore, during daily work and study, avoid squinting. Maintain a reading distance of 30–40 cm between your eyes and the book, refrain from reading while lying in bed, and regularly look into the distance to help prevent or mitigate the progression of astigmatism.
We hope the above information is helpful to you.
