Astigmatism is a common vision condition that causes blurred or distorted sight at all distances. This happens because the eye’s primary light-focusing surfaces, the cornea or the lens, possess an imperfect curvature. Instead of having a smooth, spherical shape like a basketball, the astigmatic eye is shaped more like a football, causing light to focus unevenly on the retina. It is natural to wonder whether this refractive error can disappear on its own. The factors determining if and when astigmatism alters are primarily related to age and the eye’s underlying structure.
When Astigmatism Changes or Resolves Naturally
Astigmatism is most likely to resolve or significantly decrease during the early years of life as the eye develops. Many infants are born with some degree of astigmatism, which often diminishes naturally by the time a child reaches five or six years old. This developmental phase is the most common time for the condition to spontaneously correct itself as the eyeball grows into a more spherical shape.
Beyond early childhood, the condition becomes much more stable, and true spontaneous resolution in adults is rare. Minor fluctuations in the degree of astigmatism can occur, but these are usually temporary or linked to other eye health changes. For example, conditions like severe dry eye or temporary pressure on the cornea can induce slight, transient astigmatism that improves once the underlying cause is treated.
Changes in adult astigmatism are more likely to involve a progression or worsening of the condition rather than a natural fix. As the eye ages, changes in the lens, such as those leading to cataract development, can alter the eye’s overall shape and increase the degree of astigmatism. Similarly, certain progressive corneal diseases can cause the condition to worsen over time.
Understanding Why Astigmatism is Usually Permanent
Astigmatism is a stable, permanent condition in most adults because of its structural nature. It is primarily caused by an irregular shape of the cornea (corneal astigmatism) or, less commonly, an uneven curvature of the internal lens (lenticular astigmatism). Both the cornea and the lens are specialized tissues that, once fully developed, maintain their shape rigidly.
In a normal eye, the cornea and lens work together to bend light into a single, sharp focal point on the retina. When either structure is unevenly curved, light is refracted at different angles, creating multiple focal points and resulting in blurred vision. Since the physical shape of the cornea is fixed after development, the optical error it causes remains constant.
While the structure is stable, external forces or disease can force a change in shape, though this typically worsens the condition. Progressive disorders like keratoconus cause the cornea to thin and bulge into a cone-like shape, severely increasing the degree of astigmatism. Injuries or complications following surgery can also physically alter the corneal structure, resulting in new or irregular astigmatism.
Corrective Measures for Stable Astigmatism
Since the condition rarely resolves naturally after early childhood, vision correction relies on methods that compensate for or permanently alter the eye’s stable, uneven structure. The most common non-surgical method involves prescription glasses, which use cylindrical lenses to manage the uneven light refraction. These lenses are designed with different curvatures, allowing them to bend light differently in one plane compared to the other.
This specialized lens power, indicated by the “cylinder” and “axis” values on an eyeglass prescription, works to counteract the eye’s irregular curvature. By aligning the lens axis with the specific orientation of the astigmatism, the corrective lens refocuses incoming light rays into a single point on the retina. Toric contact lenses achieve the same result but are designed to remain rotationally stable to maintain the precise alignment of the corrective cylinder.
Laser Vision Correction
Surgical procedures permanently reshape the cornea to eliminate the structural error. Photorefractive Keratectomy (PRK) and Laser-Assisted In Situ Keratomileusis (LASIK) both use an excimer laser to precisely remove microscopic amounts of corneal tissue. This controlled ablation smooths the cornea’s irregular curvature, correcting how light enters the eye. The difference between the two procedures lies in the approach to the corneal surface: LASIK involves creating a thin flap which is lifted before treatment and then repositioned, while PRK removes the surface layer, which regenerates naturally during healing.
Intraocular Lens Implants
For patients undergoing cataract surgery, a toric intraocular lens (IOL) can be implanted to correct existing astigmatism when the cloudy natural lens is removed. These interventions manage the structural problem, providing clear vision.