Astigmatism is a common vision condition caused by an irregularly shaped cornea or, less frequently, the lens inside the eye. This irregularity prevents light from focusing correctly on the retina, leading to blurred or distorted vision. Fortunately, astigmatism is a highly correctable condition, with various effective methods available to improve vision.
What is Astigmatism?
Astigmatism occurs when the front surface of the eye, the cornea, or the lens inside the eye has an uneven curve. Instead of being perfectly spherical like a basketball, the cornea might be shaped more like a football, with one meridian steeper than the other. This irregular curvature causes light rays entering the eye to focus at multiple points on the retina rather than a single, sharp point.
The uneven focusing of light results in blurred or distorted vision at all distances. Individuals with astigmatism often experience symptoms such as eyestrain, headaches, and difficulty with night vision, including halos or glare around lights. The degree of blurriness can vary, depending on the severity of the astigmatism.
Non-Surgical Correction Methods
Eyeglasses provide a common and effective non-surgical way to correct astigmatism. These glasses use specialized cylindrical lenses, often called toric lenses, which are custom-ground to compensate for the eye’s irregular curvature. These lenses have different powers in different meridians of the lens, allowing them to precisely redirect light rays to focus correctly on the retina.
Contact lenses also offer a non-surgical solution for astigmatism. Soft toric contact lenses are designed with specific orientations and weighted areas to remain stable on the eye, ensuring the different powers of the lens align with the astigmatism. Rigid gas permeable (RGP) contact lenses can also correct astigmatism by creating a smooth, spherical surface over the irregular cornea, effectively replacing its uneven shape with a uniform optical surface. Both eyeglasses and contact lenses offer reversible correction.
Surgical Correction Procedures
Surgical procedures offer more permanent solutions for correcting astigmatism by reshaping the cornea. Laser-Assisted In Situ Keratomileusis (LASIK) is a widely performed procedure where a thin flap is created on the cornea, lifted, and an excimer laser then precisely removes microscopic amounts of corneal tissue underneath to correct the irregular curvature. The flap is then repositioned, and it adheres naturally without stitches.
Photorefractive Keratectomy (PRK) is another laser-based procedure that involves removing the outer layer of corneal cells, called the epithelium, before using an excimer laser to reshape the underlying corneal tissue. The epithelium then regenerates over a few days. Small Incision Lenticule Extraction (SMILE) involves using a femtosecond laser to create a small, lens-shaped piece of tissue, known as a lenticule, inside the cornea, which is then removed through a tiny incision. This removal changes the cornea’s shape and corrects the astigmatism.
For individuals with severe astigmatism or other specific eye conditions, implantable collamer lenses (ICL) may be considered. These thin, biocompatible lenses are surgically placed inside the eye, typically between the iris and the natural lens, to permanently correct vision without removing corneal tissue.
Deciding on the Best Correction
Choosing the most suitable astigmatism correction method involves considering several individual factors. The degree and type of astigmatism play a significant role, as some methods are more effective for certain severities or corneal irregularities. Lifestyle considerations, such as participation in sports or professions requiring specific visual demands, can influence the choice between daily wear options and surgical interventions.
Personal preferences regarding convenience, maintenance, and the desire for a more permanent solution also guide the decision-making process. Underlying eye health, including the thickness of the cornea and the absence of other eye diseases, determines eligibility for surgical procedures. Ultimately, long-term vision goals and expectations are discussed to align the chosen method with the individual’s desired visual outcome.
A comprehensive eye examination and a detailed consultation with an eye care professional, such as an optometrist or ophthalmologist, are essential steps in this process. They can assess the specific characteristics of an individual’s astigmatism, evaluate overall eye health, and discuss the benefits and considerations of each correction option.