What Is Astigmatism?
Astigmatism is a common refractive error that occurs when light entering the eye fails to focus at a single point on the retina. The term originates from the Greek “a” meaning absence and “stigma” meaning point—literally, a lack of focal point.
In a healthy eye, the cornea (the clear front surface of the eye) has a smooth, evenly curved shape—much like a soccer ball—allowing light rays to bend uniformly. However, in eyes with astigmatism, the cornea has an irregular curve, more like a rugby ball. This leads to a split focus, causing blurred or distorted vision at all distances, whether near or far.
What Causes Astigmatism?
Astigmatism is often caused by an irregularly shaped cornea or, in some cases, an irregular lens inside the eye. There are two types:
- Regular Astigmatism: The principal meridians (curved planes of the cornea) are perpendicular to each other. This is the most common type and is generally correctable with glasses or contact lenses.
- Irregular Astigmatism: The meridians are not perpendicular, typically due to conditions like keratoconus or corneal scarring. This type requires more specialised treatment, often using rigid contact lenses.
Most cases of astigmatism are inherited and present from birth, but it can also develop after eye injuries or surgeries.
Common Signs and Symptoms
Astigmatism can range from mild to severe. While some individuals remain asymptomatic, many experience:
- Blurred or distorted vision at all distances
- Difficulty seeing fine details or reading small print
- Eye strain, especially during prolonged visual tasks
- Headaches, particularly after near work
- Glare sensitivity and reduced night vision
- Monocular diplopia (double vision in one eye)
- Objects may appear stretched, elongated, or “tailed”
Interestingly, some studies suggest a link between astigmatism and migraine headaches, due to the strain placed on the visual system.
Diagnosis and Detection
Astigmatism is diagnosed during a comprehensive eye examination using:
- Visual acuity tests
- Keratometry (to measure the curvature of the cornea)
- Corneal topography (for detailed mapping of corneal shape)
- Retinoscopy and refraction tests
Early detection, particularly in children, is crucial to prevent long-term issues such as amblyopia (lazy eye) or learning difficulties linked to poor visual clarity.
Treatment Options for Astigmatism
Fortunately, astigmatism is highly treatable. Options include:
Spectacles
The most common solution, using sphero-cylindrical lenses, which combine spherical and cylindrical elements to correct both astigmatism and co-existing conditions like myopia or hyperopia.
Contact Lenses
- Soft toric lenses are custom-designed for astigmatic eyes and offer enhanced comfort and flexibility.
- Rigid gas-permeable lenses (RGPs) are especially effective for irregular astigmatism, offering sharper vision than soft lenses.
- Hybrid lenses or scleral lenses may also be used in more complex cases.
Proper fit and lens movement are essential for corneal health and comfort.
Managing Irregular Astigmatism
In cases of keratoconus or corneal scarring, standard lenses are often inadequate. Specialised contact lens designs—especially RGPs—are typically recommended to ensure functional vision.
Why Treating Astigmatism Matters
When left uncorrected, moderate to high astigmatism can cause:
- Daily visual discomfort
- Increased eye fatigue
- Learning and concentration difficulties in children
- Worsening of binocular vision issues
- Heightened glare and night driving challenges
Getting the right correction significantly improves visual clarity, comfort, and quality of life.
Struggling with blurry vision or frequent eye strain?
Book an eye exam with Davida van der Merwe Optometrist and let us determine the best solution to restore your visual comfort and clarity.
📍 30 Victoria Road, Newcastle | 📞 034 312 4602 | 💬 Request Appointment
