Astigmatism is a common vision condition causing blurred or distorted sight. It originates from an imperfection in the curvature of the eye’s cornea or sometimes the lens inside the eye. This irregularity prevents light from focusing correctly on the retina.
Understanding Astigmatism
The eye’s ability to focus light depends on the precise curvature of its structures. Normally, the cornea and lens have a smoothly rounded shape, allowing incoming light to bend evenly and converge into a single, sharp focus point on the retina. In astigmatism, however, the cornea or lens is shaped more like a football. This irregular shape causes light rays entering the eye to bend unevenly, resulting in multiple focal points.
This uneven focusing leads to blurry, wavy, or stretched vision, affecting both near and distant objects. Astigmatism is broadly categorized into two main types: corneal astigmatism, which is the most frequent, occurs when the cornea itself has an irregular shape. Lenticular astigmatism involves an irregular curvature of the eye’s internal lens. While often present from birth, astigmatism can also develop following an eye injury, certain eye diseases, or some types of eye surgery.
How Astigmatism Changes Over Time
For most individuals, astigmatism tends to be a stable condition that does not spontaneously resolve on its own. While its prevalence in a population may remain consistent, the astigmatic error in individual eyes can change over time. Significant natural improvement is uncommon.
Changes in astigmatism can occur, particularly during specific life stages. In early childhood, astigmatism is common, often decreasing or is eliminated by around four years of age. Conversely, astigmatism can also develop or worsen later in life due to various factors. For instance, the development of cataracts, which cause the eye’s natural lens to thicken and change shape, can induce or exacerbate astigmatism. The mechanical pressure from eyelids or changes in the eye’s overall structure can also contribute to shifts in astigmatism.
Correcting and Managing Astigmatism
Since astigmatism does not typically improve naturally, various methods are available to correct its visual effects. Non-surgical options compensate for the eye’s irregular curvature. Eyeglasses are a primary solution, utilizing specialized cylindrical lenses that are designed to counteract the uneven bending of light caused by astigmatism. These lenses have different focusing powers in different meridians to properly direct light onto the retina.
Toric contact lenses offer another effective non-surgical approach. Unlike standard contact lenses, toric lenses have a unique design with varying thicknesses and specific orientations to provide different refractive powers across the lens surface. This allows them to correct the specific irregularities of astigmatism, and they include stabilization features to maintain their correct position on the eye with blinking and movement. Beyond corrective lenses, surgical options can permanently reshape the eye’s structures to improve vision.
Procedures like LASIK and PRK use lasers to reshape the cornea. During LASIK, a thin flap is created in the cornea, and an excimer laser then reshapes the underlying corneal tissue to correct the uneven curvature. The flap is then repositioned, allowing for relatively quick visual recovery. PRK involves removing the outermost layer of the cornea before the laser reshapes the surface. While recovery may take slightly longer than LASIK, PRK is often suitable for individuals with thinner corneas or active lifestyles. These surgical interventions aim to allow light to focus more accurately on the retina, reducing or eliminating the need for corrective lenses.
When to Seek Professional Eye Care
Individuals should consult an eye care professional if they experience symptoms suggesting a vision problem. Blurred or distorted vision is a common indicator. Other signs include frequent headaches, persistent eye strain, or difficulty seeing clearly at night, like halos or glare around lights.
Regular comprehensive eye examinations are important for detecting and monitoring astigmatism and other eye conditions. An eye care professional can accurately diagnose the condition, determine its severity, and recommend appropriate management. Early detection allows for timely intervention, preventing potential complications and ensuring visual needs are met.